barrier: Reduce the amount of disturbance by rcu_barrier() to the rest of
the system. This branch also includes improvements to
RCU_FAST_NO_HZ, which are included here due to conflicts.
fixes: Miscellaneous fixes.
inline: Remaining changes from an abortive attempt to inline
preemptible RCU's __rcu_read_lock(). These are (1) making
exit_rcu() avoid unnecessary work and (2) avoiding having
preemptible RCU record a blocked thread when the scheduler
declines to do a context switch.
srcu: Lai Jiangshan's algorithmic implementation of SRCU, including
call_srcu().
The rcu_barrier() primitive interrupts each and every CPU, registering
a callback on every CPU. Once all of these callbacks have been invoked,
rcu_barrier() knows that every callback that was registered before
the call to rcu_barrier() has also been invoked.
However, there is no point in registering a callback on a CPU that
currently has no callbacks, most especially if that CPU is in a
deep idle state. This commit therefore makes rcu_barrier() avoid
interrupting CPUs that have no callbacks. Doing this requires reworking
the handling of orphaned callbacks, otherwise callbacks could slip through
rcu_barrier()'s net by being orphaned from a CPU that rcu_barrier() had
not yet interrupted to a CPU that rcu_barrier() had already interrupted.
This reworking was needed anyway to take a first step towards weaning
RCU from the CPU_DYING notifier's use of stop_cpu().
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The current initialization of the RCU_FAST_NO_HZ per-CPU variables makes
needless and fragile assumptions about the initial value of things like
the jiffies counter. This commit therefore explicitly initializes all of
them that are better started with a non-zero value. It also adds some
comments describing the per-CPU state variables.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The current RCU_FAST_NO_HZ assumes that timers do not migrate unless a
CPU goes offline, in which case it assumes that the CPU will have to come
out of dyntick-idle mode (cancelling the timer) in order to go offline.
This is important because when RCU_FAST_NO_HZ permits a CPU to enter
dyntick-idle mode despite having RCU callbacks pending, it posts a timer
on that CPU to force a wakeup on that CPU. This wakeup ensures that the
CPU will eventually handle the end of the grace period, including invoking
its RCU callbacks.
However, Pascal Chapperon's test setup shows that the timer handler
rcu_idle_gp_timer_func() really does get invoked in some cases. This is
problematic because this can cause the CPU that entered dyntick-idle
mode despite still having RCU callbacks pending to remain in
dyntick-idle mode indefinitely, which means that its RCU callbacks might
never be invoked. This situation can result in grace-period delays or
even system hangs, which matches Pascal's observations of slow boot-up
and shutdown (https://lkml.org/lkml/2012/4/5/142). See also the bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=806548
This commit therefore causes the "should never be invoked" timer handler
rcu_idle_gp_timer_func() to use smp_call_function_single() to wake up
the CPU for which the timer was intended, allowing that CPU to invoke
its RCU callbacks in a timely manner.
Reported-by: Pascal Chapperon <pascal.chapperon@wanadoo.fr>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
When running preemptible RCU, if a task exits in an RCU read-side
critical section having blocked within that same RCU read-side critical
section, the task must be removed from the list of tasks blocking a
grace period (perhaps the current grace period, perhaps the next grace
period, depending on timing). The exit() path invokes exit_rcu() to
do this cleanup.
However, the current implementation of exit_rcu() needlessly does the
cleanup even if the task did not block within the current RCU read-side
critical section, which wastes time and needlessly increases the size
of the state space. Fix this by only doing the cleanup if the current
task is actually on the list of tasks blocking some grace period.
While we are at it, consolidate the two identical exit_rcu() functions
into a single function.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Linus Torvalds <torvalds@linux-foundation.org>
Conflicts:
kernel/rcupdate.c
Currently, PREEMPT_RCU readers are enqueued upon entry to the scheduler.
This is inefficient because enqueuing is required only if there is a
context switch, and entry to the scheduler does not guarantee a context
switch.
The commit therefore moves the enqueuing to immediately precede the
call to switch_to() from the scheduler.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Linus Torvalds <torvalds@linux-foundation.org>
Timers are subject to migration, which can lead to the following
system-hang scenario when CONFIG_RCU_FAST_NO_HZ=y:
1. CPU 0 executes synchronize_rcu(), which posts an RCU callback.
2. CPU 0 then goes idle. It cannot immediately invoke the callback,
but there is nothing RCU needs from ti, so it enters dyntick-idle
mode after posting a timer.
3. The timer gets migrated to CPU 1.
4. CPU 0 never wakes up, so the synchronize_rcu() never returns, so
the system hangs.
This commit fixes this problem by using mod_timer_pinned(), as suggested
by Peter Zijlstra, to ensure that the timer is actually posted on the
running CPU.
Reported-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Add srcu_torture_deferred_free() for srcu_ops so as to test the new
call_srcu(). Rename the original srcu_ops to srcu_sync_ops.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit implements an SRCU state machine in support of call_srcu().
The state machine is preemptible, light-weight, and single-threaded,
minimizing synchronization overhead. In particular, there is no longer
any need for synchronize_srcu() to be guarded by a mutex.
Expedited processing is handled, at least in the absence of concurrent
grace-period operations on that same srcu_struct structure, by having
the synchronize_srcu_expedited() thread take on the role of the
workqueue thread for one iteration.
There is a reasonable probability that a given SRCU callback will
be invoked on the same CPU that registered it, however, there is no
guarantee. Concurrent SRCU grace-period primitives can cause callbacks
to be executed elsewhere, even in absence of CPU-hotplug operations.
Callbacks execute in process context, but under the influence of
local_bh_disable(), so it is illegal to sleep in an SRCU callback
function.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The earlier algorithm used an "expedited" flag combined with a "trycount"
counter to differentiate between normal and expedited SRCU grace periods.
However, the difference can be encoded into a single counter with a cutoff
value and different initial values for expedited and normal SRCU grace
periods. This commit makes that change.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Conflicts:
kernel/srcu.c
Expand the calls to srcu_readers_active_idx() from srcu_readers_active()
inline. This change improves cache locality by interating over the CPUs
once rather than twice.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit implements a variant of Peter's algorithm, which may be found
at https://lkml.org/lkml/2012/2/1/119.
o Make the checking lock-free to enable parallel checking.
Parallel checking is required when (1) the original checking
task is preempted for a long time, (2) sychronize_srcu_expedited()
starts during an ongoing SRCU grace period, or (3) we wish to
avoid acquiring a lock.
o Since the checking is lock-free, we avoid a mutex in state machine
for call_srcu().
o Remove the SRCU_REF_MASK and remove the coupling with the flipping.
This might allow us to remove the preempt_disable() in future
versions, though such removal will need great care because it
rescinds the one-old-reader-per-CPU guarantee.
o Remove a smp_mb(), simplify the comments and make the smp_mb() pairs
more intuitive.
Inspired-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The safety of SRCU is provided byy wait_idx() rather than flipping.
The flipping actually prevents starvation.
This commit therefore updates the comments to more accurately and
precisely describe what is going on.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This is an optimization of the SRCU grace period. To guard against
preempted readers with old values of the counter, it suffices to scan the
old counters once more, then flip ->completed only one time. The reason
this works is that the old readers must have incremented the old set of
counters (if they have not yet incremented, then their critical section
starts after this grace period, so they may be safely ignored).
This commit therefore optimizes the second flip out in favor of a simple
rescan.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The purpose of the upper bit of SRCU's per-CPU counters is to guarantee
that no reasonable series of srcu_read_lock() and srcu_read_unlock()
operations can return the value of the counter to its original value.
This guarantee is require only after the index has been switched to
the other set of counters, so at most one srcu_read_lock() can affect
a given CPU's counter. The number of srcu_read_unlock() operations
on a given counter is limited to the number of tasks in the system,
which given the Linux kernel's current structure is limited to far less
than 2^30 on 32-bit systems and far less than 2^62 on 64-bit systems.
(Something about a limited number of bytes in the kernel's address space.)
Therefore, if srcu_read_lock() increments the upper bits, then
srcu_read_unlock() need not do so. In this case, an srcu_read_lock() and
an srcu_read_unlock() will flip the lower bit of the upper field of the
counter. An unreasonably large additional number of srcu_read_unlock()
operations would be required to return the counter to its initial value,
thus preserving the guarantee.
This commit takes this approach, which further allows it to shrink
the size of the upper field to one bit, making the number of
srcu_read_unlock() operations required to return the counter to its
initial value even more unreasonable than before.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The fastpath in __synchronize_srcu() is designed to handle cases where
there are a large number of concurrent calls for the same srcu_struct
structure. However, the Linux kernel currently does not use SRCU in
this manner, so remove the fastpath checks for simplicity.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The current implementation of synchronize_srcu_expedited() can cause
severe OS jitter due to its use of synchronize_sched(), which in turn
invokes try_stop_cpus(), which causes each CPU to be sent an IPI.
This can result in severe performance degradation for real-time workloads
and especially for short-interation-length HPC workloads. Furthermore,
because only one instance of try_stop_cpus() can be making forward progress
at a given time, only one instance of synchronize_srcu_expedited() can
make forward progress at a time, even if they are all operating on
distinct srcu_struct structures.
This commit, inspired by an earlier implementation by Peter Zijlstra
(https://lkml.org/lkml/2012/1/31/211) and by further offline discussions,
takes a strictly algorithmic bits-in-memory approach. This has the
disadvantage of requiring one explicit memory-barrier instruction in
each of srcu_read_lock() and srcu_read_unlock(), but on the other hand
completely dispenses with OS jitter and furthermore allows SRCU to be
used freely by CPUs that RCU believes to be idle or offline.
The update-side implementation handles the single read-side memory
barrier by rechecking the per-CPU counters after summing them and
by running through the update-side state machine twice.
This implementation has passed moderate rcutorture testing on both
x86 and Power. Also updated to use this_cpu_ptr() instead of per_cpu_ptr(),
as suggested by Peter Zijlstra.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Although rcutorture does invoke rcu_barrier() and friends, it cannot
really be called a torture test given that it invokes them only once
at the end of the test. This commit therefore introduces heavy-duty
rcutorture testing for rcu_barrier(), which may be carried out
concurrently with normal rcutorture testing.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The mod_timer_pinned() header comment states that it prevents timers
from being migrated to a different CPU. This is not the case, instead,
it ensures that the timer is posted to the current CPU, but does nothing
to prevent CPU-hotplug operations from migrating the timer.
This commit therefore brings the comment header into alignment with
reality.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
RCU_FAST_NO_HZ uses a timer to limit the time that a CPU with callbacks
can remain in dyntick-idle mode. This timer is cancelled when the CPU
exits idle, and therefore should never fire. However, if the timer
were migrated to some other CPU for whatever reason (1) the timer could
actually fire and (2) firing on some other CPU would fail to wake up the
CPU with callbacks, possibly resulting in sluggishness or a system hang.
This commit therfore adds a WARN_ON_ONCE() to the timer handler in order
to detect this condition.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The rcutorture initialization code ignored the error returns from
rcu_torture_onoff_init() and rcu_torture_stall_init(). The rcutorture
cleanup code failed to NULL out a number of pointers. These bugs will
normally have no effect, but this commit fixes them nevertheless.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Both Steven Rostedt's new idle-capable trace macros and the RCU_NONIDLE()
macro can cause RCU to momentarily pause out of idle without the rest
of the system being involved. This can cause rcu_prepare_for_idle()
to run through its state machine too quickly, which can in turn result
in needless scheduling-clock interrupts.
This commit therefore adds code to enable rcu_prepare_for_idle() to
distinguish between an initial entry to idle on the one hand (which needs
to advance the rcu_prepare_for_idle() state machine) and an idle reentry
due to idle-capable trace macros and RCU_NONIDLE() on the other hand
(which should avoid advancing the rcu_prepare_for_idle() state machine).
Additional state is maintained to allow the timer to be correctly reposted
when returning after a momentary pause out of idle, and even more state
is maintained to detect when new non-lazy callbacks have been enqueued
(which may require re-evaluation of the approach to idleness).
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The RCU_FAST_NO_HZ facility uses an hrtimer to wake up a CPU when
it is allowed to go into dyntick-idle mode, which is almost always
cancelled soon after. This is not what hrtimers are good at, so
this commit switches to the timer wheel.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Traces of rcu_prep_idle events can be confusing because
rcu_cleanup_after_idle() does no tracing. This commit therefore adds
this tracing.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The rcu_blocking_is_gp() function tests to see if there is only one
online CPU, and if so, synchronize_sched() and friends become no-ops.
However, for larger systems, num_online_cpus() scans a large vector,
and might be preempted while doing so. While preempted, any number
of CPUs might come online and go offline, potentially resulting in
num_online_cpus() returning 1 when there never had only been one
CPU online. This could result in a too-short RCU grace period, which
could in turn result in total failure, except that the only way that
the grace period is too short is if there is an RCU read-side critical
section spanning it. For RCU-sched and RCU-bh (which are the only
cases using rcu_blocking_is_gp()), RCU read-side critical sections
have either preemption or bh disabled, which prevents CPUs from going
offline. This in turn prevents actual failures from occurring.
This commit therefore adds a large block comment to rcu_blocking_is_gp()
documenting why it is safe. This commit also moves rcu_blocking_is_gp()
into kernel/rcutree.c, which should help prevent unwary developers from
mistaking it for a generally useful function.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Commit #0209f649 (rcu: limit rcu_node leaf-level fanout) set an upper
limit of 16 on the leaf-level fanout for the rcu_node tree. This was
needed to reduce lock contention that was induced by the synchronization
of scheduling-clock interrupts, which was in turn needed to improve
energy efficiency for moderate-sized lightly loaded servers.
However, reducing the leaf-level fanout means that there are more
leaf-level rcu_node structures in the tree, which in turn means that
RCU's grace-period initialization incurs more cache misses. This is
not a problem on moderate-sized servers with only a few tens of CPUs,
but becomes a major source of real-time latency spikes on systems with
many hundreds of CPUs. In addition, the workloads running on these large
systems tend to be CPU-bound, which eliminates the energy-efficiency
advantages of synchronizing scheduling-clock interrupts. Therefore,
these systems need maximal values for the rcu_node leaf-level fanout.
This commit addresses this problem by introducing a new kernel parameter
named RCU_FANOUT_LEAF that directly controls the leaf-level fanout.
This parameter defaults to 16 to handle the common case of a moderate
sized lightly loaded servers, but may be set higher on larger systems.
Reported-by: Mike Galbraith <efault@gmx.de>
Reported-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Pull system.h fixups for less common arch's from Paul Gortmaker:
"Here is what is hopefully the last of the system.h related fixups.
The fixes for Alpha and ia64 are code relocations consistent with what
was done for the more mainstream architectures. Note that the
diffstat lines removed vs lines added are not the same since I've
fixed some of the whitespace issues in the relocated code blocks.
However they are functionally the same. Compile tested locally, plus
these two have been in linux-next for a while.
There is also a trivial one line system.h related fix for the Tilera
arch from Chris Metcalf to fix an implict include.."
* 'systemh-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
irq_work: fix compile failure on tile from missing include
ia64: populate the cmpxchg header with appropriate code
alpha: fix build failures from system.h dismemberment
Building with IRQ_WORK configured results in
kernel/irq_work.c: In function ‘irq_work_run’:
kernel/irq_work.c:110: error: implicit declaration of function ‘irqs_disabled’
The appropriate header just needs to be included.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Format string bug fix for irqdomain debug output on 64 bit platforms
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)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=7g0b
-----END PGP SIGNATURE-----
Merge tag 'irqdomain-for-linus' of git://git.secretlab.ca/git/linux-2.6
Pull a fix for the recent irqdomain bug fixes from Grant Likely:
"I flubbed one patch in the last pull request which broke a format
string on 64 bit platforms. Here's the fix."
* tag 'irqdomain-for-linus' of git://git.secretlab.ca/git/linux-2.6:
irq_domain: fix type mismatch in debugfs output format
sizeof(void*) returns an unsigned long, but it was being used as a width parameter to a "%-*s" format string which requires an int. On 64 bit platforms this causes a type mismatch:
linux/kernel/irq/irqdomain.c:575: warning: field width should have type
'int', but argument 6 has type 'long unsigned int'
This change casts the size to an int so printf gets the right data type.
Reported-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: David Daney <david.daney@cavium.com>
Pull timer fixes from Thomas Gleixner:
"The itimer removal one is not strictly a fix, but I really wanted to
avoid a rebase of the urgent ones."
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Revert "clocksource: Load the ACPI PM clocksource asynchronously"
clockevents: tTack broadcast device mode change in tick_broadcast_switch_to_oneshot()
itimer: Use printk_once instead of WARN_ONCE
nohz: Fix stale jiffies update in tick_nohz_restart()
tick: Document TICK_ONESHOT config option
proc: stats: Use arch_idle_time for idle and iowait times if available
itimer: Schedule silent NULL pointer fixup in setitimer() for removal
Merge fixes from Andrew Morton.
* emailed from Andrew Morton <akpm@linux-foundation.org>: (14 patches)
panic: fix stack dump print on direct call to panic()
drivers/rtc/rtc-pl031.c: enable clock on all ST variants
Revert "mm: vmscan: fix misused nr_reclaimed in shrink_mem_cgroup_zone()"
hugetlb: fix race condition in hugetlb_fault()
drivers/rtc/rtc-twl.c: use static register while reading time
drivers/rtc/rtc-s3c.c: add placeholder for driver private data
drivers/rtc/rtc-s3c.c: fix compilation error
MAINTAINERS: add PCDP console maintainer
memcg: do not open code accesses to res_counter members
drivers/rtc/rtc-efi.c: fix section mismatch warning
drivers/rtc/rtc-r9701.c: reset registers if invalid values are detected
drivers/char/random.c: fix boot id uniqueness race
memcg: fix broken boolen expression
memcg: fix up documentation on global LRU
Commit 6e6f0a1f0f ("panic: don't print redundant backtraces on oops")
causes a regression where no stack trace will be printed at all for the
case where kernel code calls panic() directly while not processing an
oops, and of course there are 100's of instances of this type of call.
The original commit executed the check (!oops_in_progress), but this will
always be false because just before the dump_stack() there is a call to
bust_spinlocks(1), which does the following:
void __attribute__((weak)) bust_spinlocks(int yes)
{
if (yes) {
++oops_in_progress;
The proper way to resolve the problem that original commit tried to
solve is to avoid printing a stack dump from panic() when the either of
the following conditions is true:
1) TAINT_DIE has been set (this is done by oops_end())
This indicates and oops has already been printed.
2) oops_in_progress > 1
This guards against the rare case where panic() is invoked
a second time, or in between oops_begin() and oops_end()
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: <stable@vger.kernel.org> [3.3+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This branch fixes a bug in irq_create_mapping() where an error return
from irq_alloc_desc_from() gets ignored. It also removes irq_virq_count
to fix a bug on powerpc where the irqdomain code does not find irqs
allocated above the CONFIG_NR_IRQS boundary. The remaining patches get
rid of an completely pointless export and fix some minor bugs in the
irqdomain debug output.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)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=6Ejq
-----END PGP SIGNATURE-----
Merge tag 'irqdomain-for-linus' of git://git.secretlab.ca/git/linux-2.6
Pull irqdomain bug fixes from Grant Likely:
"This branch fixes a bug in irq_create_mapping() where an error return
from irq_alloc_desc_from() gets ignored.
It also removes irq_virq_count to fix a bug on powerpc where the
irqdomain code does not find irqs allocated above the CONFIG_NR_IRQS
boundary.
The remaining patches get rid of an completely pointless export and
fix some minor bugs in the irqdomain debug output."
* tag 'irqdomain-for-linus' of git://git.secretlab.ca/git/linux-2.6:
irq_domain: Move irq_virq_count into NOMAP revmap
irqdomain: Fix debugfs formatting
irq_domain: correct the debugfs file name
irq: Kill pointless irqd_to_hw export
irq/irq_domain: Quit ignoring error returns from irq_alloc_desc_from().
This patch replaces the old global setting of irq_virq_count that is only
used by the NOMAP mapping and instead uses a revmap_data property so that
the maximum NOMAP allocation can be set per NOMAP irq_domain.
There is exactly one user of irq_virq_count in-tree right now: PS3.
Also, irq_virq_count is only useful for the NOMAP mapping. So,
instead of having a single global irq_virq_count values, this change
drops it entirely and added a max_irq argument to irq_domain_add_nomap().
That makes it a property of an individual nomap irq domain instead of
a global system settting.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Milton Miller <miltonm@bga.com>
keyctl_session_to_parent(task) sets ->replacement_session_keyring,
it should be processed and cleared by key_replace_session_keyring().
However, this task can fork before it notices TIF_NOTIFY_RESUME and
the new child gets the bogus ->replacement_session_keyring copied by
dup_task_struct(). This is obviously wrong and, if nothing else, this
leads to put_cred(already_freed_cred).
change copy_creds() to clear this member. If copy_process() fails
before this point the wrong ->replacement_session_keyring doesn't
matter, exit_creds() won't be called.
Cc: <stable@vger.kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch fixes the irq_domain_mapping debugfs output to pad pointer
values with leading zeros so that pointer values are displayed
correctly. Otherwise you get output similar to "0x 5e0000000000000".
Also, when the irq_domain is set to 'null'
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: David Daney <david.daney@cavium.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
The actual name of the irq_domain mapping debugfs file is
"irq_domain_mapping" not "virq_mapping".
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
In commit 4bbdd45a (irq_domain/powerpc: eliminate irq_map; use
irq_alloc_desc() instead) code was added that ignores error returns
from irq_alloc_desc_from() by (silently) casting the return value to
unsigned. The negitive value error return now suddenly looks like a
valid irq number.
Commits cc79ca69 (irq_domain: Move irq_domain code from powerpc to
kernel/irq) and 1bc04f2c (irq_domain: Add support for base irq and
hwirq in legacy mappings) move this code to its current location in
irqdomain.c
The result of all of this is a null pointer dereference OOPS if one of
the error cases is hit.
The fix: Don't cast away the negativeness of the return value and then
check for errors.
Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
[grant.likely: dropped addition of new 'irq' variable]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
In the commit 77b0d60c5a,
"clockevents: Leave the broadcast device in shutdown mode when not needed",
we were bailing out too quickly in tick_broadcast_switch_to_oneshot(),
with out tracking the broadcast device mode change to 'TICKDEV_MODE_ONESHOT'.
This breaks the platforms which need broadcast device oneshot services during
deep idle states. tick_broadcast_oneshot_control() thinks that it is
in periodic mode and fails to take proper decisions based on the
CLOCK_EVT_NOTIFY_BROADCAST_[ENTER, EXIT] notifications during deep
idle entry/exit.
Fix this by tracking the broadcast device mode as 'TICKDEV_MODE_ONESHOT',
before leaving the broadcast HW device in shutdown mode if there are no active
requests for the moment.
Reported-and-tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: johnstul@us.ibm.com
Link: http://lkml.kernel.org/r/1334011304.12400.81.camel@sbsiddha-desk.sc.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
David pointed out, that WARN_ONCE() to report usage of an deprecated
misfeature make folks unhappy. Use printk_once() instead.
Andrew told me to stop grumbling and to remove the silly typecast
while touching the file.
Reported-by: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull security layer fixlet from James Morris.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
sysctl: fix write access to dmesg_restrict/kptr_restrict
Fix tick_nohz_restart() to not use a stale ktime_t "now" value when
calling tick_do_update_jiffies64(now).
If we reach this point in the loop it means that we crossed a tick
boundary since we grabbed the "now" timestamp, so at this point "now"
refers to a time in the old jiffy, so using the old value for "now" is
incorrect, and is likely to give us a stale jiffies value.
In particular, the first time through the loop the
tick_do_update_jiffies64(now) call is always a no-op, since the
caller, tick_nohz_restart_sched_tick(), will have already called
tick_do_update_jiffies64(now) with that "now" value.
Note that tick_nohz_stop_sched_tick() already uses the correct
approach: when we notice we cross a jiffy boundary, grab a new
timestamp with ktime_get(), and *then* update jiffies.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1332875377-23014-1-git-send-email-ncardwell@google.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Merge batch of fixes from Andrew Morton:
"The simple_open() cleanup was held back while I wanted for laggards to
merge things.
I still need to send a few checkpoint/restore patches. I've been
wobbly about merging them because I'm wobbly about the overall
prospects for success of the project. But after speaking with Pavel
at the LSF conference, it sounds like they're further toward
completion than I feared - apparently davem is at the "has stopped
complaining" stage regarding the net changes. So I need to go back
and re-review those patchs and their (lengthy) discussion."
* emailed from Andrew Morton <akpm@linux-foundation.org>: (16 patches)
memcg swap: use mem_cgroup_uncharge_swap fix
backlight: add driver for DA9052/53 PMIC v1
C6X: use set_current_blocked() and block_sigmask()
MAINTAINERS: add entry for sparse checker
MAINTAINERS: fix REMOTEPROC F: typo
alpha: use set_current_blocked() and block_sigmask()
simple_open: automatically convert to simple_open()
scripts/coccinelle/api/simple_open.cocci: semantic patch for simple_open()
libfs: add simple_open()
hugetlbfs: remove unregister_filesystem() when initializing module
drivers/rtc/rtc-88pm860x.c: fix rtc irq enable callback
fs/xattr.c:setxattr(): improve handling of allocation failures
fs/xattr.c:listxattr(): fall back to vmalloc() if kmalloc() failed
fs/xattr.c: suppress page allocation failure warnings from sys_listxattr()
sysrq: use SEND_SIG_FORCED instead of force_sig()
proc: fix mount -t proc -o AAA
Many users of debugfs copy the implementation of default_open() when
they want to support a custom read/write function op. This leads to a
proliferation of the default_open() implementation across the entire
tree.
Now that the common implementation has been consolidated into libfs we
can replace all the users of this function with simple_open().
This replacement was done with the following semantic patch:
<smpl>
@ open @
identifier open_f != simple_open;
identifier i, f;
@@
-int open_f(struct inode *i, struct file *f)
-{
(
-if (i->i_private)
-f->private_data = i->i_private;
|
-f->private_data = i->i_private;
)
-return 0;
-}
@ has_open depends on open @
identifier fops;
identifier open.open_f;
@@
struct file_operations fops = {
...
-.open = open_f,
+.open = simple_open,
...
};
</smpl>
[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit bfdc0b4 adds code to restrict access to dmesg_restrict,
however, it incorrectly alters kptr_restrict rather than
dmesg_restrict.
The original patch from Richard Weinberger
(https://lkml.org/lkml/2011/3/14/362) alters dmesg_restrict as
expected, and so the patch seems to have been misapplied.
This adds the CAP_SYS_ADMIN check to both dmesg_restrict and
kptr_restrict, since both are sensitive.
Reported-by: Phillip Lougher <plougher@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>
3.4: Fix an an Smatch warning that appeared in the 3.4 merge window
3.0: Fix kgdb test suite with SMP for all archs without HW single stepping
2.6.36: Fix kgdb sw breakpoints with CONFIG_DEBUG_RODATA=y limitations on x86
2.6.26: Fix oops on kgdb test suite with CONFIG_DEBUG_RODATA
Fix kgdb test suite with SMP for all archs with HW single stepping
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)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=SW2N
-----END PGP SIGNATURE-----
Merge tag 'for_linus-3.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb
Pull KGDB/KDB regression fixes from Jason Wessel:
- Fix a Smatch warning that appeared in the 3.4 merge window
- Fix kgdb test suite with SMP for all archs without HW single stepping
- Fix kgdb sw breakpoints with CONFIG_DEBUG_RODATA=y limitations on x86
- Fix oops on kgdb test suite with CONFIG_DEBUG_RODATA
- Fix kgdb test suite with SMP for all archs with HW single stepping
* tag 'for_linus-3.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
x86,kgdb: Fix DEBUG_RODATA limitation using text_poke()
kgdb,debug_core: pass the breakpoint struct instead of address and memory
kgdbts: (2 of 2) fix single step awareness to work correctly with SMP
kgdbts: (1 of 2) fix single step awareness to work correctly with SMP
kgdbts: Fix kernel oops with CONFIG_DEBUG_RODATA
kdb: Fix smatch warning on dbg_io_ops->is_console
Fixes mostly, including:
* Patch series that hopefully fixes races between the freezer and request_firmware()
and request_firmware_nowait() for good, with two cleanups from Stephen Boyd on top.
* Runtime PM fix from Alan Stern preventing tasks from getting stuck indefinitely
in the runtime PM wait queue.
* Device PM QoS update from MyungJoo Ham introducing a new variant of
pm_qos_update_request() allowing the callers to specify a timeout.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.18 (GNU/Linux)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=ligR
-----END PGP SIGNATURE-----
Merge tag 'pm-for-3.4-part-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management updates from Rafael Wysocki:
- Patch series that hopefully fixes races between the freezer and
request_firmware() and request_firmware_nowait() for good, with two
cleanups from Stephen Boyd on top.
- Runtime PM fix from Alan Stern preventing tasks from getting stuck
indefinitely in the runtime PM wait queue.
- Device PM QoS update from MyungJoo Ham introducing a new variant of
pm_qos_update_request() allowing the callers to specify a timeout.
* tag 'pm-for-3.4-part-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM / QoS: add pm_qos_update_request_timeout() API
firmware_class: Move request_firmware_nowait() to workqueues
firmware_class: Reorganize fw_create_instance()
PM / Sleep: Mitigate race between the freezer and request_firmware()
PM / Sleep: Move disabling of usermode helpers to the freezer
PM / Hibernate: Disable usermode helpers right before freezing tasks
firmware_class: Do not warn that system is not ready from async loads
firmware_class: Split _request_firmware() into three functions, v2
firmware_class: Rework usermodehelper check
PM / Runtime: don't forget to wake up waitqueue on failure
This merges some of the fixes from Paul Gortmaker for the header file
cleanup fallout.
Some of the patches are going through arch maintainer trees, and David
Howells suggested another be done differently, but this at least fixes a
few cases.
* emailed from Paul Gortmaker <paul.gortmaker@windriver.com>:
asm-generic: add linux/types.h to cmpxchg.h
firewire: restore the device.h include in linux/firewire.h
frv: fix warnings in mb93090-mb00/pci-dma.c about implicit EXPORT_SYMBOL
parisc: fix missing cmpxchg file error from system.h split
blackfin: fix cmpxchg build fails from system.h fallout
avr32: fix build failures from mis-naming of atmel_nand.h
ARM: mach-msm: fix compile fail from system.h fallout
irq_work: fix compile failure on MIPS from system.h split
Pull crypto fixes from Herbert Xu:
- Fix for CPU hotplug hang in padata.
- Avoid using cpu_active inappropriately in pcrypt and padata.
- Fix for user-space algorithm lookup hang with IV generators.
- Fix for netlink dump of algorithms where stuff went missing due to
incorrect calculation of message size.
* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
crypto: user - Fix size of netlink dump message
crypto: user - Fix lookup of algorithms with IV generator
crypto: pcrypt - Use the online cpumask as the default
padata: Fix cpu hotplug
padata: Use the online cpumask as the default
padata: Add a reference to the api documentation
