The kernel's implementation of notifier chains is unsafe. There is no
protection against entries being added to or removed from a chain while the
chain is in use. The issues were discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
We noticed that notifier chains in the kernel fall into two basic usage
classes:
"Blocking" chains are always called from a process context
and the callout routines are allowed to sleep;
"Atomic" chains can be called from an atomic context and
the callout routines are not allowed to sleep.
We decided to codify this distinction and make it part of the API. Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name). New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain. The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.
With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed. For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections. (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)
There are some limitations, which should not be too hard to live with. For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem. Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain. (This did happen in a couple of places and the code
had to be changed to avoid it.)
Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization. Instead we use RCU. The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.
Here is the list of chains that we adjusted and their classifications. None
of them use the raw API, so for the moment it is only a placeholder.
ATOMIC CHAINS
-------------
arch/i386/kernel/traps.c: i386die_chain
arch/ia64/kernel/traps.c: ia64die_chain
arch/powerpc/kernel/traps.c: powerpc_die_chain
arch/sparc64/kernel/traps.c: sparc64die_chain
arch/x86_64/kernel/traps.c: die_chain
drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
kernel/panic.c: panic_notifier_list
kernel/profile.c: task_free_notifier
net/bluetooth/hci_core.c: hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
net/ipv6/addrconf.c: inet6addr_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
net/netlink/af_netlink.c: netlink_chain
BLOCKING CHAINS
---------------
arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
arch/s390/kernel/process.c: idle_chain
arch/x86_64/kernel/process.c idle_notifier
drivers/base/memory.c: memory_chain
drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
drivers/macintosh/adb.c: adb_client_list
drivers/macintosh/via-pmu.c sleep_notifier_list
drivers/macintosh/via-pmu68k.c sleep_notifier_list
drivers/macintosh/windfarm_core.c wf_client_list
drivers/usb/core/notify.c usb_notifier_list
drivers/video/fbmem.c fb_notifier_list
kernel/cpu.c cpu_chain
kernel/module.c module_notify_list
kernel/profile.c munmap_notifier
kernel/profile.c task_exit_notifier
kernel/sys.c reboot_notifier_list
net/core/dev.c netdev_chain
net/decnet/dn_dev.c: dnaddr_chain
net/ipv4/devinet.c: inetaddr_chain
It's possible that some of these classifications are wrong. If they are,
please let us know or submit a patch to fix them. Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)
The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.
[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Need to increment the version number because of the new PCI and sysfs
capabilities of the driver. People maintaining things for distros have
asked that I do this after interface or major functional changes.
Signed-off-by: Corey Minyard <minyard@acm.org>
Acked-by: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add full driver model support for the IPMI driver. It links in the proper
bus and device support.
It adds an "ipmi" driver interface that has each BMC discovered by the
driver (as a device). These BMCs appear in the devices/platform directory.
If there are multiple interfaces to the same BMC, the driver should
discover this and will only have one BMC entry. The BMC entry will have
pointers to each interface device that connects to it.
The device information (statistics and config information) has not yet been
ported over to the driver model from proc, that will come later.
This work was based on work by Yani Ioannou. I basically rewrote it using
that code as a guide, but he still deserves credit :).
[bunk@stusta.de: make ipmi_find_bmc_guid() static]
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Yani Ioannou <yani.ioannou@gmail.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The Coverity checker found this memory leak.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
While looking to the report by Coverity in ipmi, I came across the
following issue:
The IPMI message handler relies on two defines which are the same -one in
include/linux/ipmi.h
#define IPMI_NUM_CHANNELS 0x10
and one in drivers/char/ipmi/ipmi_msghandler.
#define IPMI_MAX_CHANNELS 16
These are used interchangeably in ipmi_msghandler.c, but since the array
addr->channels[] is of size IPMI_MAX_CHANNELS, I have made a patch that
uses IPMI_MAX_CHANNELS for all the checks for the array index.
NOTE: You could probably remove the line that defines IPMI_NUM_CHANNELS
from ipmi.h, or move IPMI_MAX_CHANNELS to ipmi.h
Signed-off-by: Jayachandran C. <c.jayachandran@gmail.com>
Cc: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
...
CC [M] drivers/char/ipmi/ipmi_msghandler.o
drivers/char/ipmi/ipmi_msghandler.c:3301: `proc_ipmi_root' undeclared here (not in a function)
drivers/char/ipmi/ipmi_msghandler.c:3301: initializer element is not constant
drivers/char/ipmi/ipmi_msghandler.c:3301: (near initialization for `__ksymtab_proc_ipmi_root.value')
drivers/char/ipmi/ipmi_msghandler.c:1535: warning: `ipmb_file_read_proc' defined but not used
drivers/char/ipmi/ipmi_msghandler.c:1551: warning: `version_file_read_proc' defined but not used
drivers/char/ipmi/ipmi_msghandler.c:1561: warning: `stat_file_read_proc' defined but not used
...
CC [M] drivers/char/ipmi/ipmi_poweroff.o
drivers/char/ipmi/ipmi_poweroff.c: In function `ipmi_poweroff_init':
drivers/char/ipmi/ipmi_poweroff.c:616: warning: implicit declaration of function `unregister_sysctl_table'
drivers/char/ipmi/ipmi_poweroff.c:616: `ipmi_table_header' undeclared (first use in this function)
drivers/char/ipmi/ipmi_poweroff.c:616: (Each undeclared identifier is reported only once
drivers/char/ipmi/ipmi_poweroff.c:616: for each function it appears in.)
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I missed a use of list_for_each_rcu_safe() in -mm tree. Here is an updated
patch to fix it. This time tested on a machine that actually uses IPMI...
(Thanks to Serge Hallyn for spotting this.)
Signed-off-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Corey Minyard <minyard@acm.org>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The IPMI specifcation says the generator ID is 0x20, but that is for bits
7-1. Bit 0 is set to specify it is a software event. The correct value is
0x41. Without this fix, panic events written into the System Event Log
appear to come from an "unknown" generator, rather than from the kernel.
Signed-off-by: Jordan Hargrave <Jordan_Hargrave@dell.com>
Signed-off-by: Matt Domsch <Matt_Domsch@dell.com>
Acked-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Lots of good changes to the driver lately that userspace will care about
the version of the driver. Bump the version from 36.0 to 38.0 to be higher
than 37 that the 2.4 driver came out with a few weeks ago which doesn't
have all the same changes.
Signed-off-by: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Part of a patch was accidentally reverted, this corrects an
inconsistent spinlock use in the IPMI message handler.
Signed-off-by: Hironobu Ishii <hishii@soft.fujitsu.com>
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Use rcu_read_lock for the cmd_rcvrs list, since that was what what
intended, anyway. This means that all the users of the cmd_rcvrs_lock are
tasks, so the irq disables are no longer required for that lock and it can
become a semaphore.
Signed-off-by: Corey Minyard <minyard@acm.org>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch is rather large, but it really can't be done in smaller chunks
easily and I believe it is an important change. This has been out and tested
for a while in the latest IPMI driver release. There are no functional
changes, just changes as necessary to convert the locking over (and a few
minor style updates).
The IPMI driver uses read/write locks to ensure that things exist while they
are in use. This is bad from a number of points of view. This patch removes
the rwlocks and uses refcounts and RCU lists to manage what the locks did.
Signed-off-by: Corey Minyard <minyard@acm.org>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
I found an inconsistent spin_lock usage in ipmi_smi_msg_received.
Signed-off-by: Hironobu Ishii <hishii@soft.fujitsu.com>
Cc: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This removes the unused "all_cmd_rcvr" variable from the IPMI driver.
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Clean up various style issues in the IPMI driver. Should be no functional
changes.
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The "null message handler" in the IPMI driver is used in startup and panic
situations to handle messages. It was only designed to work with messages
from the local management controller, but in some cases it was used to get
messages from remote managmenet controllers, and the system would then
panic. This patch makes the "null message handler" in the IPMI driver more
general so it works with any kind of message.
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This adds MODULE_VERSION, MODULE_DESCRIPTION, and MODULE_AUTHOR tags to the
IPMI driver modules. Also changes the MODULE_VERSION to remove the
prepended 'v' on each value, consistent with the module versioning policy.
This patch also removes all the version information from everything except
the ipmi_msghandler module.
Signed-off-by: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
IPMI allows multiple IPMB channels on a single interface, and each channel
might have a different IPMB address. However, the driver has only one IPMB
address that it uses for everything. This patch adds new IOCTLS and a new
internal interface for setting per-channel IPMB addresses and LUNs. New
systems are coming out with support for multiple IPMB channels, and they are
broken without this patch.
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch to adds "power cycle" functionality to the IPMI power off module
ipmi_poweroff. It also contains changes to support procfs control of the
feature.
The power cycle action is considered an optional chassis control in the IPMI
specification. However, it is definitely useful when the hardware supports
it. A power cycle is usually required in order to reset a firmware in a bad
state. This action is critical to allow remote management of servers.
The implementation adds power cycle as optional to the ipmi_poweroff module.
It can be modified dynamically through the proc entry mentioned above. During
a power down and enabled, the power cycle command is sent to the BMC firmware.
If it fails either due to non-support or some error, it will retry to send
the command as power off.
Signed-off-by: Christopher A. Poblete <Chris_Poblete@dell.com>
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Clean up the timer shutdown handling in the IPMI driver.
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Correct an issue with the IPMI message layer taking a lock and calling
lower layer driver. If an error occrues at the lower layer the lock can be
taken again causing a deadlock. The lock is released before calling the
lower layer.
Signed-off-by: David Griego <dgriego@mvista.com>
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
