ftrace_match parameters are very related and I reduce the number of local
variables & parameters with it.
This is also preparation for module globbing as it would introduce more
realated variables & parameters.
Link: http://lkml.kernel.org/r/1443545176-3215-3-git-send-email-0x7f454c46@gmail.com
Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
[ Made some formatting changes ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The stack tracer was triggering the WARN_ON() in module.c:
static void module_assert_mutex_or_preempt(void)
{
#ifdef CONFIG_LOCKDEP
if (unlikely(!debug_locks))
return;
WARN_ON(!rcu_read_lock_sched_held() &&
!lockdep_is_held(&module_mutex));
#endif
}
The reason is that the stack tracer traces all function calls, and some of
those calls happen while exiting or entering user space and idle. Some of
these functions are called after RCU had already stopped watching, as RCU
does not watch userspace or idle CPUs.
If a max stack is hit, then the save_stack_trace() is called, which will
check module addresses and call module_assert_mutex_or_preempt(), and then
trigger the warning. Sad part is, the warning itself will also do a stack
trace and tigger the same warning. That probably should be fixed.
The warning was added by 0be964be0d "module: Sanitize RCU usage and
locking" but this bug has probably been around longer. But it's unlikely to
cause much harm, but the new warning causes the system to lock up.
Cc: stable@vger.kernel.org # 4.2+
Cc: Peter Zijlstra <peterz@infradead.org>
Cc:"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
"Not" is too abstract variable name - changed to clear_filter.
Removed ftrace_match_module_records function: comparison with !* or *
not does the general code in filter_parse_regex() as it works without
mod command for
sh# echo '!*' > /sys/kernel/debug/tracing/set_ftrace_filter
Link: http://lkml.kernel.org/r/1443545176-3215-2-git-send-email-0x7f454c46@gmail.com
Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
By now there isn't any subcommand for mod.
Before:
sh$ echo '*:mod:ipv6:a' > set_ftrace_filter
sh$ echo '*:mod:ipv6' > set_ftrace_filter
had the same results, but now first will result in:
sh$ echo '*:mod:ipv6:a' > set_ftrace_filter
-bash: echo: write error: Invalid argument
Also, I clarified ftrace_mod_callback code a little.
Link: http://lkml.kernel.org/r/1443545176-3215-1-git-send-email-0x7f454c46@gmail.com
Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
[ converted 'if (ret == 0)' to 'if (!ret)' ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
__trace_sched_switch_state() is the last remaining PREEMPT_ACTIVE
user, move trace_sched_switch() from prepare_task_switch() to
__schedule() and propagate the @preempt argument.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
To cover the common case of sorting an array of pointers, Daniel
Wagner recently modified the library sort() to use a specific swap
function for size==8, in addition to the size==4 case which was
already handled. Since sizeof(long) is either 4 or 8,
ftrace_swap_ips() is redundant and we can just let sort() pick an
appropriate and fast swap callback.
Link: http://lkml.kernel.org/r/1441834023-13130-1-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The kernel now has kstrdup_const/kfree_const for reusing .rodata
(typically string literals) when possible; there's no reason to
duplicate that logic in the tracing system. Moreover, as the comment
above core_kernel_data states, it may not always return true for
.rodata - that is for example the case on x86_64, where we thus end up
kstrdup'ing all the passed-in strings.
Arguably, testing for .rodata explicitly (as kstrdup_const does) is
also more correct: I don't think one is supposed to be able to change
the name after creating the event_subsystem by passing the address of
a static char (but non-const) array.
Link: http://lkml.kernel.org/r/1441833841-12955-1-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add the tracer options to instances options directory as well. Only add the
options for tracers that are allowed to be enabled by an instance. But note,
that tracer options are global. That is, tracer options enabled in an
instance, also take affect at the top level and in other instances.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Allow instances to have their own options, at least for the core options
(non tracer specific ones). There are a few global options that should not
be added to instances, like enabling of trace_printk, and the sched comm
recording, which do not have a specific trace instance associated to them.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In preparation for the multi buffer instances to have their own trace_flags,
the check in ftrace_trace_stack() needs to test the trace_array descriptor
flag that is for the current event, not the global_trace descriptor.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In preparation of having the multi buffer instances having their own trace
option flags, the trace option files needs a way to not only pass in the
flag they represent, but also the trace_array descriptor.
A new field is added to the trace_array descriptor called trace_flags_index,
which is a 32 byte character array representing a bit. This array is simply
filled with the index of the array, where
index_array[n] = n;
Then the address of this array is passed to the file callbacks instead of
the index of the flag index. Then to retrieve both the flag index and the
trace_array descriptor:
data is the passed in argument.
index = *(unsigned char *)data;
data -= index;
/* Now data points to the address of the array in the trace_array */
tr = container_of(data, struct trace_array, trace_flags_index);
Suggested-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In preparation to make trace options per instance, the global trace_flags
needs to be moved from being a global variable to a field within the trace
instance trace_array structure.
There's still more work to do, as there's some functions that use
trace_flags without passing in a way to get to the current_trace array. For
those, the global_trace is used directly (from trace.c). This includes
setting and clearing the trace_flags. This means that when a new instance is
created, it just gets the trace_flags of the global_trace and will not be
able to modify them. Depending on the functions that have access to the
trace_array, the flags of an instance may not affect parts of its trace,
where the global_trace is used. These will be fixed in future changes.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The sleep-time and graph-time options are only for the function graph tracer
and are not used by anything else. As tracer options are now visible when
the tracer is not activated, its better to move the function graph specific
tracer options into the function graph tracer.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In the effort to move the global trace_flags to the tracing instances, the
direct access to trace_flags must be removed from trace_printk.c
Instead, add a new trace_printk_enabled boolean that is set by a new access
function trace_printk_control(), that will enable or disable trace_printk.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add a enum that denotes the last bit of the trace_flags and have a
BUILD_BUG_ON(last_bit > 32).
If we add more bits than we have in trace_flags, the kernel wont build.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
There are options that are unique to a specific tracer (like function and
function graph). Currently, these options are only visible in the options
directory when the tracer is enabled.
This has been a pain, especially for something like the func_stack_trace
option that if used inappropriately, could bring the system to a crawl. But
the only way to see it, is to enable the function tracer.
For example, if one had done:
# cd /sys/kernel/tracing
# echo __schedule > set_ftrace_filter
# echo 1 > options/func_stack_trace
# echo function > current_tracer
The __schedule call will be traced and a stack trace will also be recorded
there. Now when you were done, you may do...
# echo nop > current_tracer
# echo > set_ftrace_filter
But you forgot to disable the func_stack_trace. The only way to disable it
is to re-enable function tracing first. If you do not add a filter to
set_ftrace_filter and just do:
# echo function > current_tracer
Now you would be performing a stack trace on *every* function! On some
systems, that causes a live lock. Others may take a few minutes to fix your
mistake.
Having the func_stack_trace option visible allows you to check it and
disable it before enabling the funtion tracer.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Only create the stacktrace trace option when CONFIG_STACKTRACE is
configured.
Cleaned up the ftrace_trace_stack() function call a little to allow better
encapsulation of the stacktrace trace flag.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the function tracer is not compiled in, do not create the option files
for it.
Fix up both the sched_wakeup and irqsoff tracers to handle the change.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Use a cute little macro trick to keep the names of the trace flags file
guaranteed to match the corresponding masks.
The macro TRACE_FLAGS is defined as a serious of enum names followed by
the string name of the file that matches it. For example:
#define TRACE_FLAGS \
C(PRINT_PARENT, "print-parent"), \
C(SYM_OFFSET, "sym-offset"), \
C(SYM_ADDR, "sym-addr"), \
C(VERBOSE, "verbose"),
Now we can define the following:
#undef C
#define C(a, b) TRACE_ITER_##a##_BIT
enum trace_iterator_bits { TRACE_FLAGS };
The above creates:
enum trace_iterator_bits {
TRACE_ITER_PRINT_PARENT_BIT,
TRACE_ITER_SYM_OFFSET_BIT,
TRACE_ITER_SYM_ADDR_BIT,
TRACE_ITER_VERBOSE_BIT,
};
Then we can redefine C as:
#undef C
#define C(a, b) TRACE_ITER_##a = (1 << TRACE_ITER_##a##_BIT)
enum trace_iterator_flags { TRACE_FLAGS };
Which creates:
enum trace_iterator_flags {
TRACE_ITER_PRINT_PARENT = (1 << TRACE_ITER_PRINT_PARENT_BIT),
TRACE_ITER_SYM_OFFSET = (1 << TRACE_ITER_SYM_OFFSET_BIT),
TRACE_ITER_SYM_ADDR = (1 << TRACE_ITER_SYM_ADDR_BIT),
TRACE_ITER_VERBOSE = (1 << TRACE_ITER_VERBOSE_BIT),
};
Then finally we can create the list of file names:
#undef C
#define C(a, b) b
static const char *trace_options[] = {
TRACE_FLAGS
NULL
};
Which creates:
static const char *trace_options[] = {
"print-parent",
"sym-offset",
"sym-addr",
"verbose",
NULL
};
The importance of this is that the strings match the bit index.
trace_options[TRACE_ITER_SYM_ADDR_BIT] == "sym-addr"
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Using enums with FLAG_BIT and then defining a FLAG = (1 << FLAG_BIT), is a
bit more robust as we require that there are no bits out of order or skipped
to match the file names that represent the bits.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
There was a time where the function tracing would disable interrupts unless
specifically told not to, where it would only disable preemption. With the
new lockless code, the function tracing never disalbes interrupts and just
uses disabling of preemption. Remove the option "ftrace_preempt" as it does
nothing anyway.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In order to facilitate making all tracer options visible even when the
tracer is not active, we need to get rid of duplicate options. Any option
that is shared between multiple tracers really should be a main option.
As the wakeup and irqsoff tracers both use the "display-graph" option, and
use it exactly the same way, move that option from the tracer options to the
main options and consolidate them.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
seq_print_user_ip() is used in only one location in one file. Turn it into a
static function. We could inject its code into the caller, but that would
make the code a bit too complex. Keep the code separate.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
seq_print_userip_objs() is used only in one location, in one file. Instead
of having it as an external function, go one further than making it static,
but inject is code into its only user. It doesn't make the calling function
much more complex.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In preparation for having trace options be per instance, the trace_array
needs to be passed to the trace_buffer_unlock_commit(). The
trace_event_buffer_lock_reserve() already passes in the trace_event_file
where the trace_array can be derived from.
Also added a "__init" to the boot up test event plus function tracing
function function_test_events_call().
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
ftrace_trace_stack_regs() is used in only one place, and because that is
such a simple function, just move its code into the location that it was
used in (trace_buffer_unlock_commit_regs()).
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This patch makes is_good_name return bool to improve readability
due to this particular function only using either one or zero as its
return value.
No functional change.
Link: http://lkml.kernel.org/r/1442929393-4753-2-git-send-email-bywxiaobai@163.com
Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The changes with more meat are:
o Allowing the trace event filters to filter on CPU number and process ids
o Two new markers for trace output latency were added
(10 and 100 msec latencies)
o Have tracing_thresh filter function profiling time
I also worked on modifying the ring buffer code for some future
work, and moved the adding of the timestamp around. One of my changes
caused a regression, and since other changes were built on top of it
and already tested, I had to operate a revert of that change. Instead
of rebasing, this change set has the code that caused a regression
as well as the code to revert that change without touching the other
changes that were made on top of it.
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Merge tag 'trace-v4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing update from Steven Rostedt:
"Mostly this is just clean ups and micro optimizations.
The changes with more meat are:
- Allowing the trace event filters to filter on CPU number and
process ids
- Two new markers for trace output latency were added (10 and 100
msec latencies)
- Have tracing_thresh filter function profiling time
I also worked on modifying the ring buffer code for some future work,
and moved the adding of the timestamp around. One of my changes
caused a regression, and since other changes were built on top of it
and already tested, I had to operate a revert of that change. Instead
of rebasing, this change set has the code that caused a regression as
well as the code to revert that change without touching the other
changes that were made on top of it"
* tag 'trace-v4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ring-buffer: Revert "ring-buffer: Get timestamp after event is allocated"
tracing: Don't make assumptions about length of string on task rename
tracing: Allow triggers to filter for CPU ids and process names
ftrace: Format MCOUNT_ADDR address as type unsigned long
tracing: Introduce two additional marks for delay
ftrace: Fix function_graph duration spacing with 7-digits
ftrace: add tracing_thresh to function profile
tracing: Clean up stack tracing and fix fentry updates
ring-buffer: Reorganize function locations
ring-buffer: Make sure event has enough room for extend and padding
ring-buffer: Get timestamp after event is allocated
ring-buffer: Move the adding of the extended timestamp out of line
ring-buffer: Add event descriptor to simplify passing data
ftrace: correct the counter increment for trace_buffer data
tracing: Fix for non-continuous cpu ids
tracing: Prefer kcalloc over kzalloc with multiply
Pull networking updates from David Miller:
"Another merge window, another set of networking changes. I've heard
rumblings that the lightweight tunnels infrastructure has been voted
networking change of the year. But what do I know?
1) Add conntrack support to openvswitch, from Joe Stringer.
2) Initial support for VRF (Virtual Routing and Forwarding), which
allows the segmentation of routing paths without using multiple
devices. There are some semantic kinks to work out still, but
this is a reasonably strong foundation. From David Ahern.
3) Remove spinlock fro act_bpf fast path, from Alexei Starovoitov.
4) Ignore route nexthops with a link down state in ipv6, just like
ipv4. From Andy Gospodarek.
5) Remove spinlock from fast path of act_gact and act_mirred, from
Eric Dumazet.
6) Document the DSA layer, from Florian Fainelli.
7) Add netconsole support to bcmgenet, systemport, and DSA. Also
from Florian Fainelli.
8) Add Mellanox Switch Driver and core infrastructure, from Jiri
Pirko.
9) Add support for "light weight tunnels", which allow for
encapsulation and decapsulation without bearing the overhead of a
full blown netdevice. From Thomas Graf, Jiri Benc, and a cast of
others.
10) Add Identifier Locator Addressing support for ipv6, from Tom
Herbert.
11) Support fragmented SKBs in iwlwifi, from Johannes Berg.
12) Allow perf PMUs to be accessed from eBPF programs, from Kaixu Xia.
13) Add BQL support to 3c59x driver, from Loganaden Velvindron.
14) Stop using a zero TX queue length to mean that a device shouldn't
have a qdisc attached, use an explicit flag instead. From Phil
Sutter.
15) Use generic geneve netdevice infrastructure in openvswitch, from
Pravin B Shelar.
16) Add infrastructure to avoid re-forwarding a packet in software
that was already forwarded by a hardware switch. From Scott
Feldman.
17) Allow AF_PACKET fanout function to be implemented in a bpf
program, from Willem de Bruijn"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1458 commits)
netfilter: nf_conntrack: make nf_ct_zone_dflt built-in
netfilter: nf_dup{4, 6}: fix build error when nf_conntrack disabled
net: fec: clear receive interrupts before processing a packet
ipv6: fix exthdrs offload registration in out_rt path
xen-netback: add support for multicast control
bgmac: Update fixed_phy_register()
sock, diag: fix panic in sock_diag_put_filterinfo
flow_dissector: Use 'const' where possible.
flow_dissector: Fix function argument ordering dependency
ixgbe: Resolve "initialized field overwritten" warnings
ixgbe: Remove bimodal SR-IOV disabling
ixgbe: Add support for reporting 2.5G link speed
ixgbe: fix bounds checking in ixgbe_setup_tc for 82598
ixgbe: support for ethtool set_rxfh
ixgbe: Avoid needless PHY access on copper phys
ixgbe: cleanup to use cached mask value
ixgbe: Remove second instance of lan_id variable
ixgbe: use kzalloc for allocating one thing
flow: Move __get_hash_from_flowi{4,6} into flow_dissector.c
ixgbe: Remove unused PCI bus types
...
The commit a4543a2fa9 "ring-buffer: Get timestamp after event is
allocated" is needed for some future work. But after adding it, there is a
race somewhere that causes the saved timestamp to have a slight shift, and
get ahead of the actual timestamp and make it look like time goes backwards.
I'm still looking into why this happens, but in the mean time, this is
holding up other work to get in. I'm reverting the change for now (which
makes the problem go away), and will add it back after I know what is wrong
and fix it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull core block updates from Jens Axboe:
"This first core part of the block IO changes contains:
- Cleanup of the bio IO error signaling from Christoph. We used to
rely on the uptodate bit and passing around of an error, now we
store the error in the bio itself.
- Improvement of the above from myself, by shrinking the bio size
down again to fit in two cachelines on x86-64.
- Revert of the max_hw_sectors cap removal from a revision again,
from Jeff Moyer. This caused performance regressions in various
tests. Reinstate the limit, bump it to a more reasonable size
instead.
- Make /sys/block/<dev>/queue/discard_max_bytes writeable, by me.
Most devices have huge trim limits, which can cause nasty latencies
when deleting files. Enable the admin to configure the size down.
We will look into having a more sane default instead of UINT_MAX
sectors.
- Improvement of the SGP gaps logic from Keith Busch.
- Enable the block core to handle arbitrarily sized bios, which
enables a nice simplification of bio_add_page() (which is an IO hot
path). From Kent.
- Improvements to the partition io stats accounting, making it
faster. From Ming Lei.
- Also from Ming Lei, a basic fixup for overflow of the sysfs pending
file in blk-mq, as well as a fix for a blk-mq timeout race
condition.
- Ming Lin has been carrying Kents above mentioned patches forward
for a while, and testing them. Ming also did a few fixes around
that.
- Sasha Levin found and fixed a use-after-free problem introduced by
the bio->bi_error changes from Christoph.
- Small blk cgroup cleanup from Viresh Kumar"
* 'for-4.3/core' of git://git.kernel.dk/linux-block: (26 commits)
blk: Fix bio_io_vec index when checking bvec gaps
block: Replace SG_GAPS with new queue limits mask
block: bump BLK_DEF_MAX_SECTORS to 2560
Revert "block: remove artifical max_hw_sectors cap"
blk-mq: fix race between timeout and freeing request
blk-mq: fix buffer overflow when reading sysfs file of 'pending'
Documentation: update notes in biovecs about arbitrarily sized bios
block: remove bio_get_nr_vecs()
fs: use helper bio_add_page() instead of open coding on bi_io_vec
block: kill merge_bvec_fn() completely
md/raid5: get rid of bio_fits_rdev()
md/raid5: split bio for chunk_aligned_read
block: remove split code in blkdev_issue_{discard,write_same}
btrfs: remove bio splitting and merge_bvec_fn() calls
bcache: remove driver private bio splitting code
block: simplify bio_add_page()
block: make generic_make_request handle arbitrarily sized bios
blk-cgroup: Drop unlikely before IS_ERR(_OR_NULL)
block: don't access bio->bi_error after bio_put()
block: shrink struct bio down to 2 cache lines again
...
Pull scheduler updates from Ingo Molnar:
"The biggest change in this cycle is the rewrite of the main SMP load
balancing metric: the CPU load/utilization. The main goal was to make
the metric more precise and more representative - see the changelog of
this commit for the gory details:
9d89c257df ("sched/fair: Rewrite runnable load and utilization average tracking")
It is done in a way that significantly reduces complexity of the code:
5 files changed, 249 insertions(+), 494 deletions(-)
and the performance testing results are encouraging. Nevertheless we
need to keep an eye on potential regressions, since this potentially
affects every SMP workload in existence.
This work comes from Yuyang Du.
Other changes:
- SCHED_DL updates. (Andrea Parri)
- Simplify architecture callbacks by removing finish_arch_switch().
(Peter Zijlstra et al)
- cputime accounting: guarantee stime + utime == rtime. (Peter
Zijlstra)
- optimize idle CPU wakeups some more - inspired by Facebook server
loads. (Mike Galbraith)
- stop_machine fixes and updates. (Oleg Nesterov)
- Introduce the 'trace_sched_waking' tracepoint. (Peter Zijlstra)
- sched/numa tweaks. (Srikar Dronamraju)
- misc fixes and small cleanups"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits)
sched/deadline: Fix comment in enqueue_task_dl()
sched/deadline: Fix comment in push_dl_tasks()
sched: Change the sched_class::set_cpus_allowed() calling context
sched: Make sched_class::set_cpus_allowed() unconditional
sched: Fix a race between __kthread_bind() and sched_setaffinity()
sched: Ensure a task has a non-normalized vruntime when returning back to CFS
sched/numa: Fix NUMA_DIRECT topology identification
tile: Reorganize _switch_to()
sched, sparc32: Update scheduler comments in copy_thread()
sched: Remove finish_arch_switch()
sched, tile: Remove finish_arch_switch
sched, sh: Fold finish_arch_switch() into switch_to()
sched, score: Remove finish_arch_switch()
sched, avr32: Remove finish_arch_switch()
sched, MIPS: Get rid of finish_arch_switch()
sched, arm: Remove finish_arch_switch()
sched/fair: Clean up load average references
sched/fair: Provide runnable_load_avg back to cfs_rq
sched/fair: Remove task and group entity load when they are dead
sched/fair: Init cfs_rq's sched_entity load average
...
generalize FETCH_FUNC_NAME(memory, string) into
strncpy_from_unsafe() and fix sparse warnings that were
present in original implementation.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
By extending the filter rules by more generic fields
we can write triggers filters like
echo 'stacktrace if cpu == 1' > \
/sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger
or
echo 'stacktrace if comm == sshd' > \
/sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger
CPU and COMM are not part of struct trace_entry. We could add the two
new fields to ftrace_common_field list and fix up all depending
sides. But that looks pretty ugly. Another thing I would like to
avoid that the 'format' file contents changes.
All this can be avoided by introducing another list which contains
non field members of struct trace_entry.
Link: http://lkml.kernel.org/r/1439210146-24707-1-git-send-email-daniel.wagner@bmw-carit.de
Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
According to the perf_event_map_fd and index, the function
bpf_perf_event_read() can convert the corresponding map
value to the pointer to struct perf_event and return the
Hardware PMU counter value.
Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
By copying BPF related operation to uprobe processing path, this patch
allow users attach BPF programs to uprobes like what they are already
doing on kprobes.
After this patch, users are allowed to use PERF_EVENT_IOC_SET_BPF on a
uprobe perf event. Which make it possible to profile user space programs
and kernel events together using BPF.
Because of this patch, CONFIG_BPF_EVENTS should be selected by
CONFIG_UPROBE_EVENT to ensure trace_call_bpf() is compiled even if
KPROBE_EVENT is not set.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1435716878-189507-3-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Mathieu reported that since 317f394160 ("sched: Move the second half
of ttwu() to the remote cpu") trace_sched_wakeup() can happen out of
context of the waker.
This is a problem when you want to analyse wakeup paths because it is
now very hard to correlate the wakeup event to whoever issued the
wakeup.
OTOH trace_sched_wakeup() is issued at the point where we set
p->state = TASK_RUNNING, which is right were we hand the task off to
the scheduler, so this is an important point when looking at
scheduling behaviour, up to here its been the wakeup path everything
hereafter is due to scheduler policy.
To bridge this gap, introduce a second tracepoint: trace_sched_waking.
It is guaranteed to be called in the waker context.
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Francis Giraldeau <francis.giraldeau@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150609091336.GQ3644@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently we have two different ways to signal an I/O error on a BIO:
(1) by clearing the BIO_UPTODATE flag
(2) by returning a Linux errno value to the bi_end_io callback
The first one has the drawback of only communicating a single possible
error (-EIO), and the second one has the drawback of not beeing persistent
when bios are queued up, and are not passed along from child to parent
bio in the ever more popular chaining scenario. Having both mechanisms
available has the additional drawback of utterly confusing driver authors
and introducing bugs where various I/O submitters only deal with one of
them, and the others have to add boilerplate code to deal with both kinds
of error returns.
So add a new bi_error field to store an errno value directly in struct
bio and remove the existing mechanisms to clean all this up.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Commit 4104d326b6 ("ftrace: Remove global function list and call function
directly") simplified the ftrace code by removing the global_ops list with a
new design. But this cleanup also broke the filtering of PIDs that are added
to the set_ftrace_pid file.
Add back the proper hooks to have pid filtering working once again.
Cc: stable@vger.kernel.org # 3.16+
Reported-by: Matt Fleming <matt@console-pimps.org>
Reported-by: Richard Weinberger <richard.weinberger@gmail.com>
Tested-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
A fine granulity support for delay would be very useful when profiling
VM logics, such as page allocation including page reclaim and memory
compaction with function graph.
Thus, this patch adds two additional marks with two changes.
- An equal sign in mark selection function is removed to align code
behavior with comments and documentation.
- The function graph example related to delay in ftrace.txt is updated
to cover all supported marks.
Link: http://lkml.kernel.org/r/1436626300-1679-3-git-send-email-jungseoklee85@gmail.com
Cc: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Jungseok Lee <jungseoklee85@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Jungseok Lee noticed the following:
Currently, row's width of 7-digit duration numbers not aligned with
other cases like the following example.
3) $ 3999884 us | }
3) | finish_task_switch() {
3) 0.365 us | _raw_spin_unlock_irq();
3) 3.333 us | }
3) $ 3999976 us | }
3) $ 3999979 us | } /* schedule */
As adding a single white space in case of 7-digit numbers, the format
could be unified easily as follows.
3) $ 2237472 us | }
3) | finish_task_switch() {
3) 0.364 us | _raw_spin_unlock_irq();
3) 3.125 us | }
3) $ 2237556 us | }
3) $ 2237559 us | } /* schedule */
Instead of making a special case for 7-digit numbers, the logic
of the len and the space loop is slightly modified to make the
two cases have the same format.
Link: http://lkml.kernel.org/r/1436626300-1679-2-git-send-email-jungseoklee85@gmail.com
Reported-by: Jungseok Lee <jungseoklee85@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This patch extends tracing_thresh functionality to function profile tracer.
If tracing_thresh is set, print those entries only,
whose average is > tracing thresh.
Link: http://lkml.kernel.org/r/1434972488-8571-1-git-send-email-umesh.t@samsung.com
Signed-off-by: Umesh Tiwari <umesh.t@samsung.com>
[ Removed unnecessary 'moved' comment ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Akashi Takahiro was porting the stack tracer to arm64 and found some
issues with it. One was that it repeats the top function, due to the
stack frame added by the mcount caller and added by itself. This
was added when fentry came in, and before fentry created its own stack
frame. But x86's fentry now creates its own stack frame, and there's
no need to insert the function again.
This also cleans up the code a bit, where it doesn't need to do something
special for fentry, and doesn't include insertion of a duplicate
entry for the called function being traced.
Link: http://lkml.kernel.org/r/55A646EE.6030402@linaro.org
Some-suggestions-by: Jungseok Lee <jungseoklee85@gmail.com>
Some-suggestions-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Functions in ring-buffer.c have gotten interleaved between different
use cases. Move the functions around to get like functions closer
together. This may or may not help gcc keep cache locality, but it
makes it a little easier to work with the code.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Now that events only add time extends after it is committed, in case
an event comes in before it can discard the allocated event, the time
extend needs to be stored within the event. If the event is bigger
than then size needed for the time extend, padding must be added.
The minimum padding size is 8 bytes. Thus if the event is 12 bytes
(size of time extend + 4), there will not be enough room to add both
the time extend and padding. Make sure all events are either 8 bytes
or 16 or more bytes.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Move the capturing of the timestamp to after an event is allocated.
If the event is not a commit (where it is an event that preempted
another event), then no timestamp is needed, because the delta of
nested events is always zero.
If the event starts on a new page, no delta needs to be calculated
as the full timestamp will be added to the page header, and the
event will have a delta of zero.
Now if the event requires a time extend (the delta does not fit
in the 27 bit delta slot in the header), then the event is discarded,
the length is extended to hold the TIME_EXTEND event that allows for
a 59 bit delta, and the commit is tried again.
If the event can't be discarded (another event came in after it),
then the TIME_EXTEND is added directly to the allocated event and
the rest of the event is given padding.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Requiring a extended time stamp is an uncommon occurrence, and it is
best to do it out of line when needed.
Add a noinline function that handles the extended timestamp and
have it called with an unlikely to completely move it out of the
fast path.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Add rb_event_info descriptor to pass event info to functions a bit
easier than using a bunch of parameters. This will also allow for
changing the code around a bit to find better fast paths.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
In ftrace_dump, for disabling buffer, iter.tr->trace_buffer.data is used.
But for enabling, iter.trace_buffer->data is used.
Even though, both point to same buffer, for readability, same convention
should be used.
Link: http://lkml.kernel.org/r/1434972306-20043-1-git-send-email-umesh.t@samsung.com
Signed-off-by: Umesh Tiwari <umesh.t@samsung.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently exception occures due to access beyond buffer_iter
range while using index of cpu bigger than num_possible_cpus().
Below there is an example for such exception when we use
cpus 0,1,16,17.
In order to fix buffer allocation size for non-continuous cpu ids
we allocate according to the max cpu id and not according to the
amount of possible cpus.
Example:
$ cat /sys/kernel/debug/tracing/per_cpu/cpu1/trace
Path: /bin/busybox
CPU: 0 PID: 82 Comm: cat Not tainted 4.0.0 #29
task: 80734c80 ti: 80012000 task.ti: 80012000
[ECR ]: 0x00220100 => Invalid Read @ 0x00000000 by insn @ 0x800abafc
[EFA ]: 0x00000000
[BLINK ]: ring_buffer_read_finish+0x24/0x64
[ERET ]: rb_check_pages+0x20/0x188
[STAT32]: 0x00001a00 :
BTA: 0x800abafc SP: 0x80013f0c FP: 0x57719cf8
LPS: 0x200036b4 LPE: 0x200036b8 LPC: 0x00000000
r00: 0x8002aca0 r01: 0x00001606 r02: 0x00000000
r03: 0x00000001 r04: 0x00000000 r05: 0x804b4954
r06: 0x00030003 r07: 0x8002a260 r08: 0x00000286
r09: 0x00080002 r10: 0x00001006 r11: 0x807351a4
r12: 0x00000001
Stack Trace:
rb_check_pages+0x20/0x188
ring_buffer_read_finish+0x24/0x64
tracing_release+0x4e/0x170
__fput+0x62/0x158
task_work_run+0xa2/0xd4
do_notify_resume+0x52/0x7c
resume_user_mode_begin+0xdc/0xe0
Link: http://lkml.kernel.org/r/1433835155-6894-3-git-send-email-gilf@ezchip.com
Signed-off-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: Gil Fruchter <gilf@ezchip.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Use kcalloc for allocating an array instead of kzalloc with multiply,
as that is what kcalloc is used for.
Found with checkpatch.
Link: http://lkml.kernel.org/r/1433835155-6894-2-git-send-email-gilf@ezchip.com
Signed-off-by: Gil Fruchter <gilf@ezchip.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Fengguang Wu's tests triggered a bug in the branch tracer's start up
test when CONFIG_DEBUG_PREEMPT set. This was because that config
adds some debug logic in the per cpu field, which calls back into
the branch tracer.
The branch tracer has its own recursive checks, but uses a per cpu
variable to implement it. If retrieving the per cpu variable calls
back into the branch tracer, you can see how things will break.
Instead of using a per cpu variable, use the trace_recursion field
of the current task struct. Simply set a bit when entering the
branch tracing and clear it when leaving. If the bit is set on
entry, just don't do the tracing.
There's also the case with lockdep, as the local_irq_save() called
before the recursion can also trigger code that can call back into
the function. Changing that to a raw_local_irq_save() will protect
that as well.
This prevents the recursion and the inevitable crash that follows.
Link: http://lkml.kernel.org/r/20150630141803.GA28071@wfg-t540p.sh.intel.com
Cc: stable@vger.kernel.org # 3.10+
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
"monitonic raw". Also some enhancements to make the ring buffer even
faster. But the biggest and most noticeable change is the renaming of
the ftrace* files, structures and variables that have to deal with
trace events.
Over the years I've had several developers tell me about their confusion
with what ftrace is compared to events. Technically, "ftrace" is the
infrastructure to do the function hooks, which include tracing and also
helps with live kernel patching. But the trace events are a separate
entity altogether, and the files that affect the trace events should
not be named "ftrace". These include:
include/trace/ftrace.h -> include/trace/trace_events.h
include/linux/ftrace_event.h -> include/linux/trace_events.h
Also, functions that are specific for trace events have also been renamed:
ftrace_print_*() -> trace_print_*()
(un)register_ftrace_event() -> (un)register_trace_event()
ftrace_event_name() -> trace_event_name()
ftrace_trigger_soft_disabled()-> trace_trigger_soft_disabled()
ftrace_define_fields_##call() -> trace_define_fields_##call()
ftrace_get_offsets_##call() -> trace_get_offsets_##call()
Structures have been renamed:
ftrace_event_file -> trace_event_file
ftrace_event_{call,class} -> trace_event_{call,class}
ftrace_event_buffer -> trace_event_buffer
ftrace_subsystem_dir -> trace_subsystem_dir
ftrace_event_raw_##call -> trace_event_raw_##call
ftrace_event_data_offset_##call-> trace_event_data_offset_##call
ftrace_event_type_funcs_##call -> trace_event_type_funcs_##call
And a few various variables and flags have also been updated.
This has been sitting in linux-next for some time, and I have not heard
a single complaint about this rename breaking anything. Mostly because
these functions, variables and structures are mostly internal to the
tracing system and are seldom (if ever) used by anything external to that.
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Merge tag 'trace-v4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"This patch series contains several clean ups and even a new trace
clock "monitonic raw". Also some enhancements to make the ring buffer
even faster. But the biggest and most noticeable change is the
renaming of the ftrace* files, structures and variables that have to
deal with trace events.
Over the years I've had several developers tell me about their
confusion with what ftrace is compared to events. Technically,
"ftrace" is the infrastructure to do the function hooks, which include
tracing and also helps with live kernel patching. But the trace
events are a separate entity altogether, and the files that affect the
trace events should not be named "ftrace". These include:
include/trace/ftrace.h -> include/trace/trace_events.h
include/linux/ftrace_event.h -> include/linux/trace_events.h
Also, functions that are specific for trace events have also been renamed:
ftrace_print_*() -> trace_print_*()
(un)register_ftrace_event() -> (un)register_trace_event()
ftrace_event_name() -> trace_event_name()
ftrace_trigger_soft_disabled() -> trace_trigger_soft_disabled()
ftrace_define_fields_##call() -> trace_define_fields_##call()
ftrace_get_offsets_##call() -> trace_get_offsets_##call()
Structures have been renamed:
ftrace_event_file -> trace_event_file
ftrace_event_{call,class} -> trace_event_{call,class}
ftrace_event_buffer -> trace_event_buffer
ftrace_subsystem_dir -> trace_subsystem_dir
ftrace_event_raw_##call -> trace_event_raw_##call
ftrace_event_data_offset_##call-> trace_event_data_offset_##call
ftrace_event_type_funcs_##call -> trace_event_type_funcs_##call
And a few various variables and flags have also been updated.
This has been sitting in linux-next for some time, and I have not
heard a single complaint about this rename breaking anything. Mostly
because these functions, variables and structures are mostly internal
to the tracing system and are seldom (if ever) used by anything
external to that"
* tag 'trace-v4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (33 commits)
ring_buffer: Allow to exit the ring buffer benchmark immediately
ring-buffer-benchmark: Fix the wrong type
ring-buffer-benchmark: Fix the wrong param in module_param
ring-buffer: Add enum names for the context levels
ring-buffer: Remove useless unused tracing_off_permanent()
ring-buffer: Give NMIs a chance to lock the reader_lock
ring-buffer: Add trace_recursive checks to ring_buffer_write()
ring-buffer: Allways do the trace_recursive checks
ring-buffer: Move recursive check to per_cpu descriptor
ring-buffer: Add unlikelys to make fast path the default
tracing: Rename ftrace_get_offsets_##call() to trace_event_get_offsets_##call()
tracing: Rename ftrace_define_fields_##call() to trace_event_define_fields_##call()
tracing: Rename ftrace_event_type_funcs_##call to trace_event_type_funcs_##call
tracing: Rename ftrace_data_offset_##call to trace_event_data_offset_##call
tracing: Rename ftrace_raw_##call event structures to trace_event_raw_##call
tracing: Rename ftrace_trigger_soft_disabled() to trace_trigger_soft_disabled()
tracing: Rename FTRACE_EVENT_FL_* flags to EVENT_FILE_FL_*
tracing: Rename struct ftrace_subsystem_dir to trace_subsystem_dir
tracing: Rename ftrace_event_name() to trace_event_name()
tracing: Rename FTRACE_MAX_EVENT to TRACE_EVENT_TYPE_MAX
...
I could not come up with a situation where the operand counter (cnt)
could go below zero, so I added a WARN_ON_ONCE(cnt < 0). Vince was
able to trigger that warn on with his fuzzer test, but didn't have
a filter input that caused it.
Later, Sasha Levin was able to trigger that same warning, and was
able to give me the filter string that triggered it. It was simply
a single operation ">".
I wrapped the filtering code in a userspace program such that I could
single step through the logic. With a single operator the operand
counter can legitimately go below zero, and should be reported to the
user as an error, but should not produce a kernel warning. The
WARN_ON_ONCE(cnt < 0) should be just a "if (cnt < 0) break;" and the
code following it will produce the error message for the user.
While debugging this, I found that there was another bug that let
the pointer to the filter string go beyond the filter string.
This too was fixed.
Finally, there was a typo in a stub function that only gets compiled
if trace events is disabled but tracing is enabled (I'm not even sure
that's possible).
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Merge tag 'trace-fixes-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
"This isn't my 4.2 pull request (yet). I found a few more bugs that I
would have sent to fix 4.1, but since 4.1 is already out, I'm sending
this before sending my 4.2 request (which is ready to go).
After fixing the previous filter issue reported by Vince Weaver, I
could not come up with a situation where the operand counter (cnt)
could go below zero, so I added a WARN_ON_ONCE(cnt < 0). Vince was
able to trigger that warn on with his fuzzer test, but didn't have a
filter input that caused it.
Later, Sasha Levin was able to trigger that same warning, and was able
to give me the filter string that triggered it. It was simply a
single operation ">".
I wrapped the filtering code in a userspace program such that I could
single step through the logic. With a single operator the operand
counter can legitimately go below zero, and should be reported to the
user as an error, but should not produce a kernel warning. The
WARN_ON_ONCE(cnt < 0) should be just a "if (cnt < 0) break;" and the
code following it will produce the error message for the user.
While debugging this, I found that there was another bug that let the
pointer to the filter string go beyond the filter string. This too
was fixed.
Finally, there was a typo in a stub function that only gets compiled
if trace events is disabled but tracing is enabled (I'm not even sure
that's possible)"
* tag 'trace-fixes-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix typo from "static inlin" to "static inline"
tracing/filter: Do not allow infix to exceed end of string
tracing/filter: Do not WARN on operand count going below zero
Part of the disassembly of do_blk_trace_setup:
231b: e8 00 00 00 00 callq 2320 <do_blk_trace_setup+0x50>
231c: R_X86_64_PC32 strlen+0xfffffffffffffffc
2320: eb 0a jmp 232c <do_blk_trace_setup+0x5c>
2322: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
2328: 48 83 c3 01 add $0x1,%rbx
232c: 48 39 d8 cmp %rbx,%rax
232f: 76 47 jbe 2378 <do_blk_trace_setup+0xa8>
2331: 41 80 3c 1c 2f cmpb $0x2f,(%r12,%rbx,1)
2336: 75 f0 jne 2328 <do_blk_trace_setup+0x58>
2338: 41 c6 04 1c 5f movb $0x5f,(%r12,%rbx,1)
233d: 4c 89 e7 mov %r12,%rdi
2340: e8 00 00 00 00 callq 2345 <do_blk_trace_setup+0x75>
2341: R_X86_64_PC32 strlen+0xfffffffffffffffc
2345: eb e1 jmp 2328 <do_blk_trace_setup+0x58>
Yep, that's right: gcc isn't smart enough to realize that replacing '/' by
'_' cannot change the strlen(), so we call it again and again (at least
when a '/' is found). Even if gcc were that smart, this construction
would still loop over the string twice, once for the initial strlen() call
and then the open-coded loop.
Let's simply use strreplace() instead.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Liked-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's no point in starting over every time we see a ','...
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The trace.h header when called without CONFIG_EVENT_TRACING enabled
(seldom done), will not compile because of a typo in the protocol
of trace_event_enum_update().
Cc: stable@vger.kernel.org # 4.1+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
While debugging a WARN_ON() for filtering, I found that it is possible
for the filter string to be referenced after its end. With the filter:
# echo '>' > /sys/kernel/debug/events/ext4/ext4_truncate_exit/filter
The filter_parse() function can call infix_get_op() which calls
infix_advance() that updates the infix filter pointers for the cnt
and tail without checking if the filter is already at the end, which
will put the cnt to zero and the tail beyond the end. The loop then calls
infix_next() that has
ps->infix.cnt--;
return ps->infix.string[ps->infix.tail++];
The cnt will now be below zero, and the tail that is returned is
already passed the end of the filter string. So far the allocation
of the filter string usually has some buffer that is zeroed out, but
if the filter string is of the exact size of the allocated buffer
there's no guarantee that the charater after the nul terminating
character will be zero.
Luckily, only root can write to the filter.
Cc: stable@vger.kernel.org # 2.6.33+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When testing the fix for the trace filter, I could not come up with
a scenario where the operand count goes below zero, so I added a
WARN_ON_ONCE(cnt < 0) to the logic. But there is legitimate case
that it can happen (although the filter would be wrong).
# echo '>' > /sys/kernel/debug/events/ext4/ext4_truncate_exit/filter
That is, a single operation without any operands will hit the path
where the WARN_ON_ONCE() can trigger. Although this is harmless,
and the filter is reported as a error. But instead of spitting out
a warning to the kernel dmesg, just fail nicely and report it via
the proper channels.
Link: http://lkml.kernel.org/r/558C6082.90608@oracle.com
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: stable@vger.kernel.org # 2.6.33+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull networking updates from David Miller:
1) Add TX fast path in mac80211, from Johannes Berg.
2) Add TSO/GRO support to ibmveth, from Thomas Falcon
3) Move away from cached routes in ipv6, just like ipv4, from Martin
KaFai Lau.
4) Lots of new rhashtable tests, from Thomas Graf.
5) Run ingress qdisc lockless, from Alexei Starovoitov.
6) Allow servers to fetch TCP packet headers for SYN packets of new
connections, for fingerprinting. From Eric Dumazet.
7) Add mode parameter to pktgen, for testing receive. From Alexei
Starovoitov.
8) Cache access optimizations via simplifications of build_skb(), from
Alexander Duyck.
9) Move page frag allocator under mm/, also from Alexander.
10) Add xmit_more support to hv_netvsc, from KY Srinivasan.
11) Add a counter guard in case we try to perform endless reclassify
loops in the packet scheduler.
12) Extern flow dissector to be programmable and use it in new "Flower"
classifier. From Jiri Pirko.
13) AF_PACKET fanout rollover fixes, performance improvements, and new
statistics. From Willem de Bruijn.
14) Add netdev driver for GENEVE tunnels, from John W Linville.
15) Add ingress netfilter hooks and filtering, from Pablo Neira Ayuso.
16) Fix handling of epoll edge triggers in TCP, from Eric Dumazet.
17) Add an ECN retry fallback for the initial TCP handshake, from Daniel
Borkmann.
18) Add tail call support to BPF, from Alexei Starovoitov.
19) Add several pktgen helper scripts, from Jesper Dangaard Brouer.
20) Add zerocopy support to AF_UNIX, from Hannes Frederic Sowa.
21) Favor even port numbers for allocation to connect() requests, and
odd port numbers for bind(0), in an effort to help avoid
ip_local_port_range exhaustion. From Eric Dumazet.
22) Add Cavium ThunderX driver, from Sunil Goutham.
23) Allow bpf programs to access skb_iif and dev->ifindex SKB metadata,
from Alexei Starovoitov.
24) Add support for T6 chips in cxgb4vf driver, from Hariprasad Shenai.
25) Double TCP Small Queues default to 256K to accomodate situations
like the XEN driver and wireless aggregation. From Wei Liu.
26) Add more entropy inputs to flow dissector, from Tom Herbert.
27) Add CDG congestion control algorithm to TCP, from Kenneth Klette
Jonassen.
28) Convert ipset over to RCU locking, from Jozsef Kadlecsik.
29) Track and act upon link status of ipv4 route nexthops, from Andy
Gospodarek.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1670 commits)
bridge: vlan: flush the dynamically learned entries on port vlan delete
bridge: multicast: add a comment to br_port_state_selection about blocking state
net: inet_diag: export IPV6_V6ONLY sockopt
stmmac: troubleshoot unexpected bits in des0 & des1
net: ipv4 sysctl option to ignore routes when nexthop link is down
net: track link-status of ipv4 nexthops
net: switchdev: ignore unsupported bridge flags
net: Cavium: Fix MAC address setting in shutdown state
drivers: net: xgene: fix for ACPI support without ACPI
ip: report the original address of ICMP messages
net/mlx5e: Prefetch skb data on RX
net/mlx5e: Pop cq outside mlx5e_get_cqe
net/mlx5e: Remove mlx5e_cq.sqrq back-pointer
net/mlx5e: Remove extra spaces
net/mlx5e: Avoid TX CQE generation if more xmit packets expected
net/mlx5e: Avoid redundant dev_kfree_skb() upon NOP completion
net/mlx5e: Remove re-assignment of wq type in mlx5e_enable_rq()
net/mlx5e: Use skb_shinfo(skb)->gso_segs rather than counting them
net/mlx5e: Static mapping of netdev priv resources to/from netdev TX queues
net/mlx4_en: Use HW counters for rx/tx bytes/packets in PF device
...
When the following filter is used it causes a warning to trigger:
# cd /sys/kernel/debug/tracing
# echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter
-bash: echo: write error: Invalid argument
# cat events/ext4/ext4_truncate_exit/filter
((dev==1)blocks==2)
^
parse_error: No error
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1223 at kernel/trace/trace_events_filter.c:1640 replace_preds+0x3c5/0x990()
Modules linked in: bnep lockd grace bluetooth ...
CPU: 3 PID: 1223 Comm: bash Tainted: G W 4.1.0-rc3-test+ #450
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
0000000000000668 ffff8800c106bc98 ffffffff816ed4f9 ffff88011ead0cf0
0000000000000000 ffff8800c106bcd8 ffffffff8107fb07 ffffffff8136b46c
ffff8800c7d81d48 ffff8800d4c2bc00 ffff8800d4d4f920 00000000ffffffea
Call Trace:
[<ffffffff816ed4f9>] dump_stack+0x4c/0x6e
[<ffffffff8107fb07>] warn_slowpath_common+0x97/0xe0
[<ffffffff8136b46c>] ? _kstrtoull+0x2c/0x80
[<ffffffff8107fb6a>] warn_slowpath_null+0x1a/0x20
[<ffffffff81159065>] replace_preds+0x3c5/0x990
[<ffffffff811596b2>] create_filter+0x82/0xb0
[<ffffffff81159944>] apply_event_filter+0xd4/0x180
[<ffffffff81152bbf>] event_filter_write+0x8f/0x120
[<ffffffff811db2a8>] __vfs_write+0x28/0xe0
[<ffffffff811dda43>] ? __sb_start_write+0x53/0xf0
[<ffffffff812e51e0>] ? security_file_permission+0x30/0xc0
[<ffffffff811dc408>] vfs_write+0xb8/0x1b0
[<ffffffff811dc72f>] SyS_write+0x4f/0xb0
[<ffffffff816f5217>] system_call_fastpath+0x12/0x6a
---[ end trace e11028bd95818dcd ]---
Worse yet, reading the error message (the filter again) it says that
there was no error, when there clearly was. The issue is that the
code that checks the input does not check for balanced ops. That is,
having an op between a closed parenthesis and the next token.
This would only cause a warning, and fail out before doing any real
harm, but it should still not caues a warning, and the error reported
should work:
# cd /sys/kernel/debug/tracing
# echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter
-bash: echo: write error: Invalid argument
# cat events/ext4/ext4_truncate_exit/filter
((dev==1)blocks==2)
^
parse_error: Meaningless filter expression
And give no kernel warning.
Link: http://lkml.kernel.org/r/20150615175025.7e809215@gandalf.local.home
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: stable@vger.kernel.org # 2.6.31+
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
It's useful to do per-cpu histograms.
Suggested-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
bpf_trace_printk() is a helper function used to debug eBPF programs.
Let socket and TC programs use it as well.
Note, it's DEBUG ONLY helper. If it's used in the program,
the kernel will print warning banner to make sure users don't use
it in production.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
eBPF programs attached to kprobes need to filter based on
current->pid, uid and other fields, so introduce helper functions:
u64 bpf_get_current_pid_tgid(void)
Return: current->tgid << 32 | current->pid
u64 bpf_get_current_uid_gid(void)
Return: current_gid << 32 | current_uid
bpf_get_current_comm(char *buf, int size_of_buf)
stores current->comm into buf
They can be used from the programs attached to TC as well to classify packets
based on current task fields.
Update tracex2 example to print histogram of write syscalls for each process
instead of aggregated for all.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
It takes a while until the ring_buffer_benchmark module is removed
when the ring buffer hammer is running. It is because it takes
few seconds and kthread_should_stop() is not being checked.
This patch adds the check for kthread termination into the producer.
It uses the existing @kill_test flag to finish the kthreads as
cleanly as possible.
It disables printing the "ERROR" message when the kthread is going.
It makes sure that producer does not go into the 10sec sleep
when it is being killed.
Finally, it does not call wait_to_die() when kthread_should_stop()
already returns true.
Link: http://lkml.kernel.org/r/20150615155428.GD3135@pathway.suse.cz
Signed-off-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The macro 'module_param' shows that the type of the
variable disable_reader and write_iteration is unsigned
integer. so, we change their type form int to unsigned int.
Link: http://lkml.kernel.org/r/1433923927-67782-1-git-send-email-long.wanglong@huawei.com
Signed-off-by: Wang Long <long.wanglong@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The {producer|consumer}_{nice|fifo} parameters are integer
type, we should use 'int' as the second param in module_param.
For example(consumer_fifo):
the default value of consumer_fifo is -1.
Without this patch:
# cat /sys/module/ring_buffer_benchmark/parameters/consumer_fifo
4294967295
With this patch:
# cat /sys/module/ring_buffer_benchmark/parameters/consumer_fifo
-1
Link: http://lkml.kernel.org/r/1433923873-67712-1-git-send-email-long.wanglong@huawei.com
Signed-off-by: Wang Long <long.wanglong@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As this is already exported from tracing side via commit d9847d310a
("tracing: Allow BPF programs to call bpf_ktime_get_ns()"), we might
as well want to move it to the core, so also networking users can make
use of it, e.g. to measure diffs for certain flows from ingress/egress.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The tracing_off_permanent() call is a way to disable all ring_buffers.
Nothing uses it and nothing should use it, as tracing_off() and
friends are better, as they disable the ring buffers related to
tracing. The tracing_off_permanent() even disabled non tracing
ring buffers. This is a bit drastic, and was added to handle NMIs
doing outputs that could corrupt the ring buffer when only tracing
used them. It is now obsolete and adds a little overhead, it should
be removed.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently, if an NMI does a dump of a ring buffer, it disables
all ring buffers from ever doing any writes again. This is because
it wont take the locks for the cpu_buffer and this can cause
corruption if it preempted a read, or a read happens on another
CPU for the current cpu buffer. This is a bit overkill.
First, it should at least try to take the lock, and if it fails
then disable it. Also, there's no need to disable all ring
buffers, even those that are unrelated to what is being read.
Only disable the per cpu ring buffer that is being read if
it can not get the lock for it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The ring_buffer_write() function isn't protected by the trace recursive
writes. Luckily, this function is not used as much and is unlikely
to ever recurse. But it should still have the protection, because
even a call to ring_buffer_lock_reserve() could cause ring buffer
corruption if called when ring_buffer_write() is being used.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Currently the trace_recursive checks are only done if CONFIG_TRACING
is enabled. That was because there use to be a dependency with tracing
for the recursive checks (it used the task_struct trace recursive
variable). But now it uses its own variable and there is no dependency.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Instead of using a global per_cpu variable to perform the recursive
checks into the ring buffer, use the already existing per_cpu descriptor
that is part of the ring buffer itself.
Not only does this simplify the code, it also allows for one ring buffer
to be used within the guts of the use of another ring buffer. For example
trace_printk() can now be used within the ring buffer to record changes
done by an instance into the main ring buffer. The recursion checks
will prevent the trace_printk() itself from causing recursive issues
with the main ring buffer (it is just ignored), but the recursive
checks wont prevent the trace_printk() from recording other ring buffers.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
introduce bpf_tail_call(ctx, &jmp_table, index) helper function
which can be used from BPF programs like:
int bpf_prog(struct pt_regs *ctx)
{
...
bpf_tail_call(ctx, &jmp_table, index);
...
}
that is roughly equivalent to:
int bpf_prog(struct pt_regs *ctx)
{
...
if (jmp_table[index])
return (*jmp_table[index])(ctx);
...
}
The important detail that it's not a normal call, but a tail call.
The kernel stack is precious, so this helper reuses the current
stack frame and jumps into another BPF program without adding
extra call frame.
It's trivially done in interpreter and a bit trickier in JITs.
In case of x64 JIT the bigger part of generated assembler prologue
is common for all programs, so it is simply skipped while jumping.
Other JITs can do similar prologue-skipping optimization or
do stack unwind before jumping into the next program.
bpf_tail_call() arguments:
ctx - context pointer
jmp_table - one of BPF_MAP_TYPE_PROG_ARRAY maps used as the jump table
index - index in the jump table
Since all BPF programs are idenitified by file descriptor, user space
need to populate the jmp_table with FDs of other BPF programs.
If jmp_table[index] is empty the bpf_tail_call() doesn't jump anywhere
and program execution continues as normal.
New BPF_MAP_TYPE_PROG_ARRAY map type is introduced so that user space can
populate this jmp_table array with FDs of other bpf programs.
Programs can share the same jmp_table array or use multiple jmp_tables.
The chain of tail calls can form unpredictable dynamic loops therefore
tail_call_cnt is used to limit the number of calls and currently is set to 32.
Use cases:
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
==========
- simplify complex programs by splitting them into a sequence of small programs
- dispatch routine
For tracing and future seccomp the program may be triggered on all system
calls, but processing of syscall arguments will be different. It's more
efficient to implement them as:
int syscall_entry(struct seccomp_data *ctx)
{
bpf_tail_call(ctx, &syscall_jmp_table, ctx->nr /* syscall number */);
... default: process unknown syscall ...
}
int sys_write_event(struct seccomp_data *ctx) {...}
int sys_read_event(struct seccomp_data *ctx) {...}
syscall_jmp_table[__NR_write] = sys_write_event;
syscall_jmp_table[__NR_read] = sys_read_event;
For networking the program may call into different parsers depending on
packet format, like:
int packet_parser(struct __sk_buff *skb)
{
... parse L2, L3 here ...
__u8 ipproto = load_byte(skb, ... offsetof(struct iphdr, protocol));
bpf_tail_call(skb, &ipproto_jmp_table, ipproto);
... default: process unknown protocol ...
}
int parse_tcp(struct __sk_buff *skb) {...}
int parse_udp(struct __sk_buff *skb) {...}
ipproto_jmp_table[IPPROTO_TCP] = parse_tcp;
ipproto_jmp_table[IPPROTO_UDP] = parse_udp;
- for TC use case, bpf_tail_call() allows to implement reclassify-like logic
- bpf_map_update_elem/delete calls into BPF_MAP_TYPE_PROG_ARRAY jump table
are atomic, so user space can build chains of BPF programs on the fly
Implementation details:
=======================
- high performance of bpf_tail_call() is the goal.
It could have been implemented without JIT changes as a wrapper on top of
BPF_PROG_RUN() macro, but with two downsides:
. all programs would have to pay performance penalty for this feature and
tail call itself would be slower, since mandatory stack unwind, return,
stack allocate would be done for every tailcall.
. tailcall would be limited to programs running preempt_disabled, since
generic 'void *ctx' doesn't have room for 'tail_call_cnt' and it would
need to be either global per_cpu variable accessed by helper and by wrapper
or global variable protected by locks.
In this implementation x64 JIT bypasses stack unwind and jumps into the
callee program after prologue.
- bpf_prog_array_compatible() ensures that prog_type of callee and caller
are the same and JITed/non-JITed flag is the same, since calling JITed
program from non-JITed is invalid, since stack frames are different.
Similarly calling kprobe type program from socket type program is invalid.
- jump table is implemented as BPF_MAP_TYPE_PROG_ARRAY to reuse 'map'
abstraction, its user space API and all of verifier logic.
It's in the existing arraymap.c file, since several functions are
shared with regular array map.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The ftrace_raw_##call structures are built
by macros for trace events. They have nothing to do with function tracing.
Rename them.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The ftrace_trigger_soft_disabled() tests if a
trace_event is soft disabled (called but not traced), and returns true if
it is. It has nothing to do with function tracing and should be renamed.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The FTRACE_EVENT_FL_* flags are flags to
do with the trace_event files in the tracefs directory. They are not related
to function tracing. Rename them to a more descriptive name.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The structure ftrace_subsystem_dir holds
the information about trace event subsystems. It should not be named
ftrace, rename it to trace_subsystem_dir.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. ftrace_event_name() returns the name of
an event tracepoint, has nothing to do with function tracing. Rename it
to trace_event_name().
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. Rename the max trace_event type size to
something more descriptive and appropriate.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The ftrace_output_*() and ftrace_raw_output_*()
functions represent the trace_event code. Rename them to just trace_output
or trace_raw_output.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The ftrace_event_buffer functions and data
structures are for trace_events and not for function hooks. Rename them
to trace_event_buffer*.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The structures ftrace_event_call and
ftrace_event_class have nothing to do with the function hooks, and are
really trace_event structures. Rename ftrace_event_* to trace_event_*.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The structure ftrace_event_file is really
about trace events and not "ftrace". Rename it to trace_event_file.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The functions (un)register_ftrace_event() is
really about trace_events, and the name should be register_trace_event()
instead.
Also renamed ftrace_event_reg() to trace_event_reg() for the same reason.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The name "ftrace" really refers to the function hook infrastructure. It
is not about the trace_events. The functions ftrace_print_*() are not part of
the function infrastructure, and the names can be confusing. Rename them
to be trace_print_*().
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The term "ftrace" is really the infrastructure of the function hooks,
and not the trace events. Rename ftrace_event.h to trace_events.h to
represent the trace_event infrastructure and decouple the term ftrace
from it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Expose the NMI safe accessor to the monotonic raw clock to the
tracer. The mono clock was added with commit
1b3e5c0936. The advantage of the
monotonic raw clock is that it will advance more constantly than the
monotonic clock.
Imagine someone is trying to optimize a particular program to reduce
instructions executed for a given workload while minimizing the effect
on runtime. Also suppose that NTP is running and potentially making
larger adjustments to the monotonic clock. If NTP is adjusting the
monotonic clock to advance more rapidly, the program will appear to
use fewer instructions per second but run longer than if the monotonic
raw clock had been used. The total number of instructions observed
would be the same regardless of the clock source used, but how it's
attributed to time would be affected.
Conversely if NTP is adjusting the monotonic clock to advance more
slowly, the program will appear to use more instructions per second
but run more quickly. Of course there are many sources that can cause
jitter in performance measurements on modern processors, but let's
remove NTP from the list.
The monotonic raw clock can also be useful for tracing early boot,
e.g. when debugging issues with NTP.
Link: http://lkml.kernel.org/r/20150508143037.GB1276@dreric01-Precision-T1650
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Drew Richardson <drew.richardson@arm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Critical tracepoint hooks should never call anything that takes a lock,
so they are unable to call getrawmonotonic() or ktime_get().
Export the rest of the tracing clock functions so can be used in
tracepoint hooks.
Background: We have a customer that adds their own module and registers
a tracepoint hook to sched_wakeup. They were using ktime_get() for a
time source, but it grabs a seq lock and caused a deadlock to occur.
Link: http://lkml.kernel.org/r/1430406624-22609-1-git-send-email-jsnitsel@redhat.com
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
The only caller to this function (__print_array) was getting it wrong by
passing the array length instead of buffer length. As the element size
was already being passed for other reasons it seems reasonable to push
the calculation of buffer length into the function.
Link: http://lkml.kernel.org/r/1430320727-14582-1-git-send-email-alex.bennee@linaro.org
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
