Lai Jiangshan
0b3dae68ac
workqueue: simplify is-work-item-queued-here test ...
Currently, determining whether a work item is queued on a locked pool
involves somewhat convoluted memory barrier dancing. It goes like the
following.
* When a work item is queued on a pool, work->data is updated before
work->entry is linked to the pending list with a wmb() inbetween.
* When trying to determine whether a work item is currently queued on
a pool pointed to by work->data, it locks the pool and looks at
work->entry. If work->entry is linked, we then do rmb() and then
check whether work->data points to the current pool.
This works because, work->data can only point to a pool if it
currently is or were on the pool and,
* If it currently is on the pool, the tests would obviously succeed.
* It it left the pool, its work->entry was cleared under pool->lock,
so if we're seeing non-empty work->entry, it has to be from the work
item being linked on another pool. Because work->data is updated
before work->entry is linked with wmb() inbetween, work->data update
from another pool is guaranteed to be visible if we do rmb() after
seeing non-empty work->entry. So, we either see empty work->entry
or we see updated work->data pointin to another pool.
While this works, it's convoluted, to put it mildly. With recent
updates, it's now guaranteed that work->data points to cwq only while
the work item is queued and that updating work->data to point to cwq
or back to pool is done under pool->lock, so we can simply test
whether work->data points to cwq which is associated with the
currently locked pool instead of the convoluted memory barrier
dancing.
This patch replaces the memory barrier based "are you still here,
really?" test with much simpler "does work->data points to me?" test -
if work->data points to a cwq which is associated with the currently
locked pool, the work item is guaranteed to be queued on the pool as
work->data can start and stop pointing to such cwq only under
pool->lock and the start and stop coincide with queue and dequeue.
tj: Rewrote the comments and description.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2013-02-06 18:04:53 -08:00
KGDB/KDB fixes and cleanups
2012-10-13 11:16:58 +09:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2012-12-17 15:44:47 -08:00
Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-12-11 18:12:06 -08:00
Merge branch 'for-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2012-12-12 08:18:24 -08:00
workqueue: rename kernel/workqueue_sched.h to kernel/workqueue_internal.h
2013-01-18 14:05:55 -08:00
Merge tag 'kvm-3.8-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm
2012-12-13 15:31:08 -08:00
trace: use kbasename()
2012-12-17 17:15:17 -08:00
vfs: make path_openat take a struct filename pointer
2012-10-12 20:15:09 -04:00
workqueue: implement current_is_async()
2013-01-18 14:05:56 -08:00
fs: handle failed audit_log_start properly
2012-10-09 23:33:37 -04:00
audit: optimize audit_compare_dname_path
2012-10-12 00:32:02 -04:00
audit: clean up refcounting in audit-tree
2012-08-15 12:55:22 +02:00
audit: optimize audit_compare_dname_path
2012-10-12 00:32:02 -04:00
audit: optimize audit_compare_dname_path
2012-10-12 00:32:02 -04:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal
2012-12-12 12:22:13 -08:00
userns: Teach inode_capable to understand inodes whose uids map to other namespaces.
2012-05-15 14:59:24 -07:00
Merge branch 'akpm' (Andrew's patch-bomb)
2012-12-17 20:58:12 -08:00
cgroup: rename ->create/post_create/pre_destroy/destroy() to ->css_alloc/online/offline/free()
2012-11-19 08:13:38 -08:00
compat: generic compat_sys_sched_rr_get_interval() implementation
2012-12-17 17:15:18 -08:00
context_tracking: New context tracking susbsystem
2012-11-30 11:40:07 -08:00
Merge branch 'x86-bsp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-12-11 19:56:33 -08:00
kernel/cpu_pm.c: fix various typos
2012-05-31 17:49:27 -07:00
cpuset: use N_MEMORY instead N_HIGH_MEMORY
2012-12-12 17:38:32 -08:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2012-12-16 15:40:50 -08:00
Remove all #inclusions of asm/system.h
2012-03-28 18:30:03 +01:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2012-12-17 15:44:47 -08:00
extable: Skip sorting if sorted at build time.
2012-04-19 15:06:55 -07:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2012-12-17 15:44:47 -08:00
freezer: change ptrace_stop/do_signal_stop to use freezable_schedule()
2012-10-26 14:27:49 -07:00
futex: avoid wake_futex() for a PI futex_q
2012-11-26 17:41:24 -08:00
futex: Mark get_robust_list as deprecated
2012-03-29 11:37:17 +02:00
userns: Convert in_group_p and in_egroup_p to use kgid_t
2012-05-03 03:29:33 -07:00
hrtimer: Update hrtimer base offsets each hrtimer_interrupt
2012-07-11 23:34:39 +02:00
hung task debugging: Inject NMI when hung and going to panic
2012-04-25 12:39:25 +02:00
irq_work: fix compile failure on tile from missing include
2012-04-13 13:15:16 -04:00
itimer: Use printk_once instead of WARN_ONCE
2012-04-10 11:00:30 +02:00
jump_label: Export jump_label_rate_limit()
2012-08-06 19:00:35 +03:00
vsprintf: fix %ps on non symbols when using kallsyms
2012-05-29 16:22:32 -07:00
syscalls, x86: add __NR_kcmp syscall
2012-05-31 17:49:32 -07:00
locking: Adjust spin lock inlining Kconfig options
2012-09-13 17:56:13 +02:00
kdump: remove unneeded include
2012-10-06 03:05:19 +09:00
[media] kernel:kfifo: export __kfifo_max_r symbol
2012-04-11 18:24:37 -03:00
infrastructure for saner ret_from_kernel_thread semantics
2012-10-12 13:35:07 -04:00
kprobes/x86: Fix to support jprobes on ftrace-based kprobe
2012-09-13 22:52:11 -04:00
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-12-11 18:10:49 -08:00
kthread: use N_MEMORY instead N_HIGH_MEMORY
2012-12-12 17:38:33 -08:00
brlocks/lglocks: turn into functions
2012-05-29 23:28:41 -04:00
lockdep: Check if nested lock is actually held
2012-09-13 17:00:44 +02:00
lockdep: Use KSYM_NAME_LEN'ed buffer for __get_key_name()
2012-10-24 12:39:09 +02:00
Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
2012-12-03 06:27:05 +01:00
modsign: add symbol prefix to certificate list
2012-12-03 13:06:25 +10:30
MODSIGN: Move the magic string to the end of a module and eliminate the search
2012-10-19 17:30:40 -07:00
kernel: remove reference to feature-removal-schedule.txt
2012-12-17 17:15:12 -08:00
MODSIGN: Don't use enum-type bitfields in module signature info block
2012-12-05 11:27:24 +10:30
userns: Implement unshare of the user namespace
2012-11-20 04:18:14 -08:00
padata: use __this_cpu_read per-cpu helper
2012-12-06 17:16:23 +08:00
panic: fix a possible deadlock in panic()
2012-07-30 17:25:13 -07:00
params: replace printk(KERN_<LVL>...) with pr_<lvl>(...)
2012-05-04 17:28:18 -07:00
Merge branch 'akpm' (Andrew's patch-bomb)
2012-12-17 20:58:12 -08:00
proc: Usable inode numbers for the namespace file descriptors.
2012-11-20 04:19:49 -08:00
cputime: Move thread_group_cputime() to sched code
2012-11-28 17:07:38 +01:00
printk: boot_delay should only affect output
2012-12-17 17:15:13 -08:00
propagate name change to comments in kernel source
2012-12-06 10:39:54 +01:00
Merge branch 'akpm' (Andrew's patch-bomb)
2012-12-17 20:58:12 -08:00
rcu: Add a module parameter to force use of expedited RCU primitives
2012-10-23 14:54:08 -07:00
rcu: Add a module parameter to force use of expedited RCU primitives
2012-10-23 14:54:08 -07:00
rcu: Fix TINY_RCU rcu_is_cpu_rrupt_from_idle check
2012-11-13 14:08:34 -08:00
rcu: Add a module parameter to force use of expedited RCU primitives
2012-10-23 14:54:08 -07:00
Merge branches 'urgent.2012.10.27a', 'doc.2012.11.16a', 'fixes.2012.11.13a', 'srcu.2012.10.27a', 'stall.2012.11.13a', 'tracing.2012.11.08a' and 'idle.2012.10.24a' into HEAD
2012-11-16 09:59:58 -08:00
context_tracking: New context tracking susbsystem
2012-11-30 11:40:07 -08:00
rcu: Separate accounting of callbacks from callback-free CPUs
2012-11-16 10:05:57 -08:00
rcu: Separate accounting of callbacks from callback-free CPUs
2012-11-16 10:05:57 -08:00
rcu: Separate accounting of callbacks from callback-free CPUs
2012-11-16 10:05:57 -08:00
splice: fix racy pipe->buffers uses
2012-06-13 21:16:42 +02:00
res_counter: delete res_counter_write()
2012-12-12 17:38:33 -08:00
kernel/resource.c: fix stack overflow in __reserve_region_with_split()
2012-10-06 03:05:31 +09:00
Remove all #inclusions of asm/system.h
2012-03-28 18:30:03 +01:00
seccomp: Make syscall skipping and nr changes more consistent
2012-10-02 21:14:29 +10:00
semaphore: fix improper comment reference to mutex
2012-04-05 17:15:55 -07:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2012-12-17 15:44:47 -08:00
smp: Remove ipi_call_lock[_irq]()/ipi_call_unlock[_irq]()
2012-06-05 17:27:14 +02:00
hotplug: Fix UP bug in smpboot hotplug code
2012-08-13 17:01:07 +02:00
smpboot: Provide infrastructure for percpu hotplug threads
2012-08-13 17:01:07 +02:00
cputime: Specialize irq vtime hooks
2012-10-29 21:31:32 +01:00
Merge branches 'urgent.2012.10.27a', 'doc.2012.11.16a', 'fixes.2012.11.13a', 'srcu.2012.10.27a', 'stall.2012.11.13a', 'tracing.2012.11.08a' and 'idle.2012.10.24a' into HEAD
2012-11-16 09:59:58 -08:00
cputime: Rename thread_group_times to thread_group_cputime_adjusted
2012-11-28 17:07:57 +01:00
syscalls, x86: add __NR_kcmp syscall
2012-05-31 17:49:32 -07:00
Automatic NUMA Balancing V11
2012-12-16 15:18:08 -08:00
pidns: Use task_active_pid_ns where appropriate
2012-11-19 05:59:09 -08:00
task_work: task_work_add() should not succeed after exit_task_work()
2012-09-13 16:47:34 +02:00
taskstats: cgroupstats_user_cmd() may leak on error
2012-10-06 03:05:31 +09:00
time: Move update_vsyscall definitions to timekeeper_internal.h
2012-09-24 12:38:06 -04:00
timers: Fix endless looping between cascade() and internal_add_timer()
2012-10-09 21:27:14 +02:00
userns: Convert taskstats to handle the user and pid namespaces.
2012-09-18 01:01:32 -07:00
userns: Convert setting and getting uid and gid system calls to use kuid and kgid
2012-05-03 03:28:41 -07:00
proc: Usable inode numbers for the namespace file descriptors.
2012-11-20 04:19:49 -08:00
proc: Usable inode numbers for the namespace file descriptors.
2012-11-20 04:19:49 -08:00
proc: Usable inode numbers for the namespace file descriptors.
2012-11-20 04:19:49 -08:00
propagate name change to comments in kernel source
2012-12-06 10:39:54 +01:00
watchdog: store the watchdog sample period as a variable
2012-12-17 17:15:13 -08:00
workqueue: simplify is-work-item-queued-here test
2013-02-06 18:04:53 -08:00
workqueue: remove global_cwq
2013-01-24 11:01:34 -08:00
0b3dae68ac