Milton Miller
45a5791920
call_function_many: add missing ordering ...
Paul McKenney's review pointed out two problems with the barriers in the
2.6.38 update to the smp call function many code.
First, a barrier that would force the func and info members of data to
be visible before their consumption in the interrupt handler was
missing. This can be solved by adding a smp_wmb between setting the
func and info members and setting setting the cpumask; this will pair
with the existing and required smp_rmb ordering the cpumask read before
the read of refs. This placement avoids the need a second smp_rmb in
the interrupt handler which would be executed on each of the N cpus
executing the call request. (I was thinking this barrier was present
but was not).
Second, the previous write to refs (establishing the zero that we the
interrupt handler was testing from all cpus) was performed by a third
party cpu. This would invoke transitivity which, as a recient or
concurrent addition to memory-barriers.txt now explicitly states, would
require a full smp_mb().
However, we know the cpumask will only be set by one cpu (the data
owner) and any preivous iteration of the mask would have cleared by the
reading cpu. By redundantly writing refs to 0 on the owning cpu before
the smp_wmb, the write to refs will follow the same path as the writes
that set the cpumask, which in turn allows us to keep the barrier in the
interrupt handler a smp_rmb instead of promoting it to a smp_mb (which
will be be executed by N cpus for each of the possible M elements on the
list).
I moved and expanded the comment about our (ab)use of the rcu list
primitives for the concurrent walk earlier into this function. I
considered moving the first two paragraphs to the queue list head and
lock, but felt it would have been too disconected from the code.
Cc: Paul McKinney <paulmck@linux.vnet.ibm.com>
Cc: stable@kernel.org (2.6.32 and later)
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-17 16:58:10 -07:00
Merge branch 'master' into for-next
2010-12-22 18:57:02 +01:00
sh: Enable CONFIG_GCOV_PROFILE_ALL for sh
2011-02-15 16:47:17 +09:00
Merge branch 'irq/numa' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-03-15 15:06:35 -07:00
PM / Hibernate: Reduce autotuned default image size
2011-03-15 00:45:46 +01:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-03-15 18:53:35 -07:00
tracing: Fix irqoff selftest expanding max buffer
2011-03-10 10:34:58 -05:00
pass a struct path to vfs_statfs
2010-08-09 16:48:42 -04:00
async: use workqueue for worker pool
2010-07-14 11:29:46 +02:00
netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms
2011-03-03 10:55:40 -08:00
audit: make functions static
2010-10-30 01:42:19 -04:00
in untag_chunk() we need to do alloc_chunk() a bit earlier
2010-10-30 02:18:32 -04:00
kill path_lookup()
2011-03-14 09:15:23 -04:00
netlink: kill loginuid/sessionid/sid members from struct netlink_skb_parms
2011-03-03 10:55:40 -08:00
audit mmap
2010-10-30 08:45:43 -04:00
security: add cred argument to security_capable()
2011-02-11 17:41:58 +11:00
perf: Add cgroup support
2011-02-16 13:30:48 +01:00
cgroup_freezer: update_freezer_state() does incorrect state transitions
2010-10-27 18:03:08 -07:00
posix-timers: Introduce a syscall for clock tuning.
2011-02-02 15:28:19 +01:00
llseek: automatically add .llseek fop
2010-10-15 15:53:27 +02:00
Merge branches 'x86-alternatives-for-linus', 'x86-fpu-for-linus', 'x86-hwmon-for-linus', 'x86-paravirt-for-linus', 'core-locking-for-linus' and 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-01-06 11:11:50 -08:00
cpuset: add a missing unlock in cpuset_write_resmask()
2011-03-04 17:53:38 -08:00
Merge commit 'v2.6.38-rc5' into core/locking
2011-02-16 13:33:41 +01:00
elf coredump: add extended numbering support
2010-03-06 11:26:46 -08:00
sys_personality: remove the bogus checks in sys_personality()->__set_personality() path
2010-08-09 20:45:05 -07:00
Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-01-11 11:02:13 -08:00
thp: khugepaged
2011-01-13 17:32:43 -08:00
Freezer: Fix a race during freezing of TASK_STOPPED tasks
2010-12-24 15:02:40 +01:00
Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-03-15 18:28:30 -07:00
futex: Address compiler warnings in exit_robust_list
2010-11-10 13:27:50 +01:00
kernel/groups.c: fix integer overflow in groups_search
2010-09-09 18:57:24 -07:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-03-15 18:53:35 -07:00
lockup detector: Fix grammar by adding a missing "to" in the comments
2010-08-17 09:11:52 +02:00
perf: Dynamic pmu types
2010-12-16 11:36:43 +01:00
irq_work: Use per cpu atomics instead of regular atomics
2010-12-18 15:54:48 +01:00
jump label: Make arch_jump_label_text_poke_early() optional
2010-10-29 12:56:13 -04:00
Revert "kernel: make /proc/kallsyms mode 400 to reduce ease of attacking"
2010-11-19 11:54:40 -08:00
tree-wide: fix comment/printk typos
2010-11-01 15:38:34 -04:00
kfifo: fix scatterlist usage
2010-10-01 10:50:58 -07:00
Make do_execve() take a const filename pointer
2010-08-17 18:07:43 -07:00
Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
2011-01-07 17:02:58 -08:00
sysfs: add struct file* to bin_attr callbacks
2010-05-21 09:37:31 -07:00
sched: Constify function scope static struct sched_param usage
2011-01-07 15:55:45 +01:00
fs/proc/base.c, kernel/latencytop.c: convert sprintf_symbol() to %ps
2011-01-13 08:03:16 -08:00
lockdep: Move early boot local IRQ enable/disable status to init/main.c
2011-01-20 13:32:33 +01:00
lockdep: No need to disable preemption in debug atomic ops
2010-05-04 05:38:16 +02:00
locking, lockdep: Convert sprintf_symbol to %pS
2010-11-10 10:23:58 +01:00
kernel: clean up USE_GENERIC_SMP_HELPERS
2011-01-13 08:03:08 -08:00
tracepoints: Fix section alignment using pointer array
2011-02-03 09:28:46 -05:00
mutexes, sched: Introduce arch_mutex_cpu_relax()
2010-11-26 15:05:34 +01:00
sched: Use lockdep-based checking on rcu_dereference()
2010-02-25 10:34:26 +01:00
cgroup: notify ns_cgroup deprecated
2010-10-27 18:03:09 -07:00
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
2010-03-30 22:02:32 +09:00
Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
2010-08-04 15:23:14 -07:00
ACPI, APEI, Generic Hardware Error Source POLL/IRQ/NMI notification type support
2011-01-12 03:06:19 -05:00
module: show version information for built-in modules in sysfs
2011-01-24 14:32:51 +10:30
perf: Fix cgroup vs jump_label problem
2011-03-04 11:32:52 +01:00
Add RCU check for find_task_by_vpid().
2010-08-19 17:18:02 -07:00
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
2010-03-30 22:02:32 +09:00
PM QoS: Make pm_qos settings readable
2011-03-15 00:43:18 +01:00
posix-timers: Cleanup namespace
2011-02-02 15:28:19 +01:00
timers: Export CLOCK_BOOTTIME via the posix timers interface
2011-02-21 12:53:09 -08:00
Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6
2011-03-16 15:05:40 -07:00
llseek: automatically add .llseek fop
2010-10-15 15:53:27 +02:00
Mark ptrace_{traceme,attach,detach} static
2011-03-04 09:23:30 -08:00
kernel/range.c: fix clean_sort_range() for the case of full array
2010-11-12 07:55:31 -08:00
rcu: add comment saying why DEBUG_OBJECTS_RCU_HEAD depends on PREEMPT.
2011-03-04 08:05:41 -08:00
rcu: avoid pointless blocked-task warnings
2011-01-14 04:58:08 -08:00
rcu: call __rcu_read_unlock() in exit_rcu for tiny RCU
2011-03-04 08:05:08 -08:00
rcutorture: Get rid of duplicate sched.h include
2011-03-04 08:05:17 -08:00
Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
2011-01-07 17:02:58 -08:00
rcu: limit rcu_node leaf-level fanout
2010-12-17 12:34:20 -08:00
rcu: increase synchronize_sched_expedited() batching
2010-12-17 12:34:08 -08:00
rcu,cleanup: simplify the code when cpu is dying
2010-11-29 22:01:58 -08:00
Clean up relay_alloc_page_array() slightly by using vzalloc rather than vmalloc and memset
2010-11-05 08:21:34 -07:00
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
2010-03-30 22:02:32 +09:00
resources: add arch hook for preventing allocation in reserved areas
2010-12-17 10:01:09 -08:00
rtmutex: Simplify PI algorithm and make highest prio task get lock
2011-01-27 21:13:51 -05:00
rtmutex: tester: Remove the remaining BKL leftovers
2011-02-22 22:07:22 +01:00
rtmutex: Simplify PI algorithm and make highest prio task get lock
2011-01-27 21:13:51 -05:00
rtmutex: Simplify PI algorithm and make highest prio task get lock
2011-01-27 21:13:51 -05:00
Merge branch 'config' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl
2011-03-16 17:21:00 -07:00
sched, autogroup: Stop claiming ownership of the root task group
2011-02-23 11:34:03 +01:00
sched, autogroup: Stop going ahead if autogroup is disabled
2011-02-23 11:33:59 +01:00
sched: Add some clock info to sched_debug
2010-11-23 10:29:08 +01:00
sched: No need for bootmem special cases
2010-07-17 12:06:22 +02:00
sched: No need for bootmem special cases
2010-07-17 12:06:22 +02:00
sched: Use a buddy to implement yield_task_fair()
2011-02-03 14:20:33 +01:00
sched: Resched proper CPU on yield_to()
2011-03-04 11:14:31 +01:00
sched: Rewrite tg_shares_up)
2010-11-18 13:27:46 +01:00
sched: Fix switch_from_fair()
2011-01-26 12:33:22 +01:00
Merge branch 'sched/urgent' into sched/core
2011-03-04 11:12:26 +01:00
sched_stat: Update sched_info_queue/dequeue() code comments
2010-10-24 13:29:01 +02:00
sched: Fix switch_from_fair()
2011-01-26 12:33:22 +01:00
signals: annotate lock context change on ptrace_stop()
2010-10-27 18:03:12 -07:00
call_function_many: add missing ordering
2011-03-17 16:58:10 -07:00
Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-03-15 19:23:40 -07:00
rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status
2011-01-14 04:56:49 -08:00
stop_machine: convert cpu notifier to return encapsulate errno value
2010-10-26 16:52:15 -07:00
PM / Core: Introduce struct syscore_ops for core subsystems PM
2011-03-15 00:43:46 +01:00
vfs: Add open by file handle support
2011-03-15 02:21:44 -04:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6
2011-03-16 09:15:43 -07:00
open-style analog of vfs_path_lookup()
2011-03-14 09:15:28 -04:00
sysctl: min/max bounds are optional
2010-10-15 14:42:24 -07:00
taskstats: use better ifdef for alignment
2011-01-13 08:03:19 -08:00
kprobes: Fix selftest to clear flags field for reusing probes
2010-10-14 08:55:27 +02:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-03-15 18:53:35 -07:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
2011-03-15 18:53:35 -07:00
tracepoints: Fix section alignment using pointer array
2011-02-03 09:28:46 -05:00
taskstats: use real microsecond granularity for CPU times
2010-10-27 18:03:17 -07:00
fix freeing user_struct in user cache
2010-12-29 11:31:38 -08:00
user_ns: improve the user_ns on-the-slab packaging
2011-01-13 08:03:18 -08:00
docbook: add more wait/wake/completion to device-drivers docbook
2010-10-26 17:32:41 -07:00
watchdog, nmi: Lower the severity of error messages
2011-02-10 13:21:59 +01:00
Merge branch 'for-2.6.39' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2011-03-16 08:20:19 -07:00
workqueue: implement concurrency managed dynamic worker pool
2010-06-29 10:07:14 +02:00
45a5791920