summaryrefslogtreecommitdiffstats
path: root/kernel/workqueue.c (follow)
Commit message (Collapse)AuthorAgeFilesLines
* workqueue: cond_resched() after processing each work itemTejun Heo2013-08-291-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | If !PREEMPT, a kworker running work items back to back can hog CPU. This becomes dangerous when a self-requeueing work item which is waiting for something to happen races against stop_machine. Such self-requeueing work item would requeue itself indefinitely hogging the kworker and CPU it's running on while stop_machine would wait for that CPU to enter stop_machine while preventing anything else from happening on all other CPUs. The two would deadlock. Jamie Liu reports that this deadlock scenario exists around scsi_requeue_run_queue() and libata port multiplier support, where one port may exclude command processing from other ports. With the right timing, scsi_requeue_run_queue() can end up requeueing itself trying to execute an IO which is asked to be retried while another device has an exclusive access, which in turn can't make forward progress due to stop_machine. Fix it by invoking cond_resched() after executing each work item. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jamie Liu <jamieliu@google.com> References: http://thread.gmane.org/gmane.linux.kernel/1552567 Cc: stable@vger.kernel.org -- kernel/workqueue.c | 9 +++++++++ 1 file changed, 9 insertions(+)
* Merge branch 'for-3.11-fixes' of ↵Linus Torvalds2013-08-061-10/+34
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull two workqueue fixes from Tejun Heo: "A lockdep notation update so that nested work_on_cpu() invocations don't lead to spurious lockdep warnings and fix for an unbound attr bug which made what's shown in sysfs deviate from the actual ones. Both patches have pretty limited scope" * 'for-3.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: copy workqueue_attrs with all fields workqueue: allow work_on_cpu() to be called recursively
| * workqueue: copy workqueue_attrs with all fieldsShaohua Li2013-08-011-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | $echo '0' > /sys/bus/workqueue/devices/xxx/numa $cat /sys/bus/workqueue/devices/xxx/numa I got 1. It should be 0, the reason is copy_workqueue_attrs() called in apply_workqueue_attrs() doesn't copy no_numa field. Fix it by making copy_workqueue_attrs() copy ->no_numa too. This would also make get_unbound_pool() set a pool's ->no_numa attribute according to the workqueue attributes used when the pool was created. While harmelss, as ->no_numa isn't a pool attribute, this is a bit confusing. Clear it explicitly. tj: Updated description and comments a bit. Signed-off-by: Shaohua Li <shli@fusionio.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org
| * workqueue: allow work_on_cpu() to be called recursivelyLai Jiangshan2013-07-241-10/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If the @fn call work_on_cpu() again, the lockdep will complain: > [ INFO: possible recursive locking detected ] > 3.11.0-rc1-lockdep-fix-a #6 Not tainted > --------------------------------------------- > kworker/0:1/142 is trying to acquire lock: > ((&wfc.work)){+.+.+.}, at: [<ffffffff81077100>] flush_work+0x0/0xb0 > > but task is already holding lock: > ((&wfc.work)){+.+.+.}, at: [<ffffffff81075dd9>] process_one_work+0x169/0x610 > > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock((&wfc.work)); > lock((&wfc.work)); > > *** DEADLOCK *** It is false-positive lockdep report. In this sutiation, the two "wfc"s of the two work_on_cpu() are different, they are both on stack. flush_work() can't be deadlock. To fix this, we need to avoid the lockdep checking in this case, thus we instroduce a internal __flush_work() which skip the lockdep. tj: Minor comment adjustment. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Reported-by: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com> Reported-by: Alexander Duyck <alexander.h.duyck@intel.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | kernel: delete __cpuinit usage from all core kernel filesPaul Gortmaker2013-07-151-2/+2
|/ | | | | | | | | | | | | | | | | | | | | The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the uses of the __cpuinit macros from C files in the core kernel directories (kernel, init, lib, mm, and include) that don't really have a specific maintainer. [1] https://lkml.org/lkml/2013/5/20/589 Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
* Merge branch 'for-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wqLinus Torvalds2013-07-031-1/+25
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull workqueue changes from Tejun Heo: "Surprisingly, Lai and I didn't break too many things implementing custom pools and stuff last time around and there aren't any follow-up changes necessary at this point. The only change in this pull request is Viresh's patches to make some per-cpu workqueues to behave as unbound workqueues dependent on a boot param whose default can be configured via a config option. This leads to higher processing overhead / lower bandwidth as more work items are bounced across CPUs; however, it can lead to noticeable powersave in certain configurations - ~10% w/ idlish constant workload on a big.LITTLE configuration according to Viresh. This is because per-cpu workqueues interfere with how the scheduler perceives whether or not each CPU is idle by forcing pinned tasks on them, which makes the scheduler's power-aware scheduling decisions less effective. Its effectiveness is likely less pronounced on homogenous configurations and this type of optimization can probably be made automatic; however, the changes are pretty minimal and the affected workqueues are clearly marked, so it's an easy gain for some configurations for the time being with pretty unintrusive changes." * 'for-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: fbcon: queue work on power efficient wq block: queue work on power efficient wq PHYLIB: queue work on system_power_efficient_wq workqueue: Add system wide power_efficient workqueues workqueues: Introduce new flag WQ_POWER_EFFICIENT for power oriented workqueues
| * workqueue: Add system wide power_efficient workqueuesViresh Kumar2013-05-141-1/+12
| | | | | | | | | | | | | | | | | | | | | | This patch adds system wide workqueues aligned towards power saving. This is done by allocating them with WQ_UNBOUND flag if 'wq_power_efficient' is set to 'true'. tj: updated comments a bit. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Tejun Heo <tj@kernel.org>
| * workqueues: Introduce new flag WQ_POWER_EFFICIENT for power oriented workqueuesViresh Kumar2013-05-141-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Workqueues can be performance or power-oriented. Currently, most workqueues are bound to the CPU they were created on. This gives good performance (due to cache effects) at the cost of potentially waking up otherwise idle cores (Idle from scheduler's perspective. Which may or may not be physically idle) just to process some work. To save power, we can allow the work to be rescheduled on a core that is already awake. Workqueues created with the WQ_UNBOUND flag will allow some power savings. However, we don't change the default behaviour of the system. To enable power-saving behaviour, a new config option CONFIG_WQ_POWER_EFFICIENT needs to be turned on. This option can also be overridden by the workqueue.power_efficient boot parameter. tj: Updated config description and comments. Renamed CONFIG_WQ_POWER_EFFICIENT to CONFIG_WQ_POWER_EFFICIENT_DEFAULT. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: don't perform NUMA-aware allocations on offline nodes in ↵Tejun Heo2013-05-151-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | wq_numa_init() wq_numa_init() builds per-node cpumasks which are later used to make unbound workqueues NUMA-aware. The cpumasks are allocated using alloc_cpumask_var_node() for all possible nodes. Unfortunately, on machines with off-line nodes, this leads to NUMA-aware allocations on existing bug offline nodes, which in turn triggers BUG in the memory allocation code. Fix it by using NUMA_NO_NODE for cpumask allocations for offline nodes. kernel BUG at include/linux/gfp.h:323! invalid opcode: 0000 [#1] SMP Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0+ #1 Hardware name: ProLiant BL465c G7, BIOS A19 12/10/2011 task: ffff880234608000 ti: ffff880234602000 task.ti: ffff880234602000 RIP: 0010:[<ffffffff8117495d>] [<ffffffff8117495d>] new_slab+0x2ad/0x340 RSP: 0000:ffff880234603bf8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff880237404b40 RCX: 00000000000000d0 RDX: 0000000000000001 RSI: 0000000000000003 RDI: 00000000002052d0 RBP: ffff880234603c28 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000001 R11: ffffffff812e3aa8 R12: 0000000000000001 R13: ffff8802378161c0 R14: 0000000000030027 R15: 00000000000040d0 FS: 0000000000000000(0000) GS:ffff880237800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: ffff88043fdff000 CR3: 00000000018d5000 CR4: 00000000000007f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Stack: ffff880234603c28 0000000000000001 00000000000000d0 ffff8802378161c0 ffff880237404b40 ffff880237404b40 ffff880234603d28 ffffffff815edba1 ffff880237816140 0000000000000000 ffff88023740e1c0 Call Trace: [<ffffffff815edba1>] __slab_alloc+0x330/0x4f2 [<ffffffff81174b25>] kmem_cache_alloc_node_trace+0xa5/0x200 [<ffffffff812e3aa8>] alloc_cpumask_var_node+0x28/0x90 [<ffffffff81a0bdb3>] wq_numa_init+0x10d/0x1be [<ffffffff81a0bec8>] init_workqueues+0x64/0x341 [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0 [<ffffffff819f1f31>] kernel_init_freeable+0xb7/0x1ec [<ffffffff815d50de>] kernel_init+0xe/0xf0 [<ffffffff815ff89c>] ret_from_fork+0x7c/0xb0 Code: 45 84 ac 00 00 00 f0 41 80 4d 00 40 e9 f6 fe ff ff 66 0f 1f 84 00 00 00 00 00 e8 eb 4b ff ff 49 89 c5 e9 05 fe ff ff <0f> 0b 4c 8b 73 38 44 89 ff 81 cf 00 00 20 00 4c 89 f6 48 c1 ee Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-Tested-by: Lingzhu Xiang <lxiang@redhat.com>
* | workqueue: Make schedule_work() available again to non GPL modulesMarc Dionne2013-05-141-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 8425e3d5bdbe ("workqueue: inline trivial wrappers") changed schedule_work() and schedule_delayed_work() to inline wrappers, but these rely on some symbols that are EXPORT_SYMBOL_GPL, while the original functions were EXPORT_SYMBOL. This has the effect of changing the licensing requirement for these functions and making them unavailable to non GPL modules. Make them available again by removing the restriction on the required symbols. Signed-off-by: Marc Dionne <marc.dionne@your-file-system.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: correct handling of the pool spin_lockJoonsoo Kim2013-05-141-0/+1
| | | | | | | | | | | | | | | | | | | | When we fail to mutex_trylock(), we release the pool spin_lock and do mutex_lock(). After that, we should regrab the pool spin_lock, but, regrabbing is missed in current code. So correct it. Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: workqueue_congested() shouldn't translate WORK_CPU_UNBOUND into ↵Tejun Heo2013-05-101-0/+9
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | node number df2d5ae499 ("workqueue: map an unbound workqueues to multiple per-node pool_workqueues") made unbound workqueues to map to multiple per-node pool_workqueues and accordingly updated workqueue_contested() so that, for unbound workqueues, it maps the specified @cpu to the NUMA node number to obtain the matching pool_workqueue to query the congested state. Before this change, workqueue_congested() ignored @cpu for unbound workqueues as there was only one pool_workqueue and some users (fscache) called it with WORK_CPU_UNBOUND. After the commit, this causes the following oops as WORK_CPU_UNBOUND gets translated to garbage by cpu_to_node(). BUG: unable to handle kernel paging request at ffff8803598d98b8 IP: [<ffffffff81043b7e>] unbound_pwq_by_node+0xa1/0xfa PGD 2421067 PUD 0 Oops: 0000 [#1] SMP CPU: 1 PID: 2689 Comm: cat Tainted: GF 3.9.0-fsdevel+ #4 task: ffff88003d801040 ti: ffff880025806000 task.ti: ffff880025806000 RIP: 0010:[<ffffffff81043b7e>] [<ffffffff81043b7e>] unbound_pwq_by_node+0xa1/0xfa RSP: 0018:ffff880025807ad8 EFLAGS: 00010202 RAX: 0000000000000001 RBX: ffff8800388a2400 RCX: 0000000000000003 RDX: ffff880025807fd8 RSI: ffffffff81a31420 RDI: ffff88003d8016e0 RBP: ffff880025807ae8 R08: ffff88003d801730 R09: ffffffffa00b4898 R10: ffffffff81044217 R11: ffff88003d801040 R12: 0000000064206e97 R13: ffff880036059d98 R14: ffff880038cc8080 R15: ffff880038cc82d0 FS: 00007f21afd9c740(0000) GS:ffff88003d100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: ffff8803598d98b8 CR3: 000000003df49000 CR4: 00000000000007e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Stack: ffff8800388a2400 0000000000000002 ffff880025807b18 ffffffff810442ce ffffffff81044217 ffff880000000002 ffff8800371b4080 ffff88003d112ec0 ffff880025807b38 ffffffffa00810b0 ffff880036059d88 ffff880036059be8 Call Trace: [<ffffffff810442ce>] workqueue_congested+0xb7/0x12c [<ffffffffa00810b0>] fscache_enqueue_object+0xb2/0xe8 [fscache] [<ffffffffa007facd>] __fscache_acquire_cookie+0x3b9/0x56c [fscache] [<ffffffffa00ad8fe>] nfs_fscache_set_inode_cookie+0xee/0x132 [nfs] [<ffffffffa009e112>] do_open+0x9/0xd [nfs] [<ffffffff810e804a>] do_dentry_open+0x175/0x24b [<ffffffff810e8298>] finish_open+0x41/0x51 Fix it by using smp_processor_id() if @cpu is WORK_CPU_UNBOUND. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: David Howells <dhowells@redhat.com> Tested-and-Acked-by: David Howells <dhowells@redhat.com>
* workqueue: include workqueue info when printing debug dump of a worker taskTejun Heo2013-05-011-0/+79
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | One of the problems that arise when converting dedicated custom threadpool to workqueue is that the shared worker pool used by workqueue anonimizes each worker making it more difficult to identify what the worker was doing on which target from the output of sysrq-t or debug dump from oops, BUG() and friends. This patch implements set_worker_desc() which can be called from any workqueue work function to set its description. When the worker task is dumped for whatever reason - sysrq-t, WARN, BUG, oops, lockdep assertion and so on - the description will be printed out together with the workqueue name and the worker function pointer. The printing side is implemented by print_worker_info() which is called from functions in task dump paths - sched_show_task() and dump_stack_print_info(). print_worker_info() can be safely called on any task in any state as long as the task struct itself is accessible. It uses probe_*() functions to access worker fields. It may print garbage if something went very wrong, but it wouldn't cause (another) oops. The description is currently limited to 24bytes including the terminating \0. worker->desc_valid and workder->desc[] are added and the 64 bytes marker which was already incorrect before adding the new fields is moved to the correct position. Here's an example dump with writeback updated to set the bdi name as worker desc. Hardware name: Bochs Modules linked in: Pid: 7, comm: kworker/u9:0 Not tainted 3.9.0-rc1-work+ #1 Workqueue: writeback bdi_writeback_workfn (flush-8:0) ffffffff820a3ab0 ffff88000f6e9cb8 ffffffff81c61845 ffff88000f6e9cf8 ffffffff8108f50f 0000000000000000 0000000000000000 ffff88000cde16b0 ffff88000cde1aa8 ffff88001ee19240 ffff88000f6e9fd8 ffff88000f6e9d08 Call Trace: [<ffffffff81c61845>] dump_stack+0x19/0x1b [<ffffffff8108f50f>] warn_slowpath_common+0x7f/0xc0 [<ffffffff8108f56a>] warn_slowpath_null+0x1a/0x20 [<ffffffff81200150>] bdi_writeback_workfn+0x2a0/0x3b0 ... Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Acked-by: Jan Kara <jack@suse.cz> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* workqueue: use kmem_cache_free() instead of kfree()Wei Yongjun2013-04-091-1/+1
| | | | | | | | memory allocated by kmem_cache_alloc() should be freed using kmem_cache_free(), not kfree(). Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Tejun Heo <tj@kernel.org>
* workqueue: avoid false negative WARN_ON() in destroy_workqueue()Lai Jiangshan2013-04-041-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | destroy_workqueue() performs several sanity checks before proceeding with destruction of a workqueue. One of the checks verifies that refcnt of each pwq (pool_workqueue) is over 1 as at that point there should be no in-flight work items and the only holder of pwq refs is the workqueue itself. This worked fine as a workqueue used to hold only one reference to its pwqs; however, since 4c16bd327c ("workqueue: implement NUMA affinity for unbound workqueues"), a workqueue may hold multiple references to its default pwq triggering this sanity check spuriously. Fix it by not triggering the pwq->refcnt assertion on default pwqs. An example spurious WARN trigger follows. WARNING: at kernel/workqueue.c:4201 destroy_workqueue+0x6a/0x13e() Hardware name: 4286C12 Modules linked in: sdhci_pci sdhci mmc_core usb_storage i915 drm_kms_helper drm i2c_algo_bit i2c_core video Pid: 361, comm: umount Not tainted 3.9.0-rc5+ #29 Call Trace: [<c04314a7>] warn_slowpath_common+0x7c/0x93 [<c04314e0>] warn_slowpath_null+0x22/0x24 [<c044796a>] destroy_workqueue+0x6a/0x13e [<c056dc01>] ext4_put_super+0x43/0x2c4 [<c04fb7b8>] generic_shutdown_super+0x4b/0xb9 [<c04fb848>] kill_block_super+0x22/0x60 [<c04fb960>] deactivate_locked_super+0x2f/0x56 [<c04fc41b>] deactivate_super+0x2e/0x31 [<c050f1e6>] mntput_no_expire+0x103/0x108 [<c050fdce>] sys_umount+0x2a2/0x2c4 [<c050fe0e>] sys_oldumount+0x1e/0x20 [<c085ba4d>] sysenter_do_call+0x12/0x38 tj: Rewrote description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Fengguang Wu <fengguang.wu@intel.com>
* Merge tag 'v3.9-rc5' into wq/for-3.10Tejun Heo2013-04-021-25/+30
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Writeback conversion to workqueue will be based on top of wq/for-3.10 branch to take advantage of custom attrs and NUMA support for unbound workqueues. Mainline currently contains two commits which result in non-trivial merge conflicts with wq/for-3.10 and because block/for-3.10/core is based on v3.9-rc3 which contains one of the conflicting commits, we need a pre-merge-window merge anyway. Let's pull v3.9-rc5 into wq/for-3.10 so that the block tree doesn't suffer from workqueue merge conflicts. The two conflicts and their resolutions: * e68035fb65 ("workqueue: convert to idr_alloc()") in mainline changes worker_pool_assign_id() to use idr_alloc() instead of the old idr interface. worker_pool_assign_id() goes through multiple locking changes in wq/for-3.10 causing the following conflict. static int worker_pool_assign_id(struct worker_pool *pool) { int ret; <<<<<<< HEAD lockdep_assert_held(&wq_pool_mutex); do { if (!idr_pre_get(&worker_pool_idr, GFP_KERNEL)) return -ENOMEM; ret = idr_get_new(&worker_pool_idr, pool, &pool->id); } while (ret == -EAGAIN); ======= mutex_lock(&worker_pool_idr_mutex); ret = idr_alloc(&worker_pool_idr, pool, 0, 0, GFP_KERNEL); if (ret >= 0) pool->id = ret; mutex_unlock(&worker_pool_idr_mutex); >>>>>>> c67bf5361e7e66a0ff1f4caf95f89347d55dfb89 return ret < 0 ? ret : 0; } We want locking from the former and idr_alloc() usage from the latter, which can be combined to the following. static int worker_pool_assign_id(struct worker_pool *pool) { int ret; lockdep_assert_held(&wq_pool_mutex); ret = idr_alloc(&worker_pool_idr, pool, 0, 0, GFP_KERNEL); if (ret >= 0) { pool->id = ret; return 0; } return ret; } * eb2834285c ("workqueue: fix possible pool stall bug in wq_unbind_fn()") updated wq_unbind_fn() such that it has single larger for_each_std_worker_pool() loop instead of two separate loops with a schedule() call inbetween. wq/for-3.10 renamed pool->assoc_mutex to pool->manager_mutex causing the following conflict (earlier function body and comments omitted for brevity). static void wq_unbind_fn(struct work_struct *work) { ... spin_unlock_irq(&pool->lock); <<<<<<< HEAD mutex_unlock(&pool->manager_mutex); } ======= mutex_unlock(&pool->assoc_mutex); >>>>>>> c67bf5361e7e66a0ff1f4caf95f89347d55dfb89 schedule(); <<<<<<< HEAD for_each_cpu_worker_pool(pool, cpu) ======= >>>>>>> c67bf5361e7e66a0ff1f4caf95f89347d55dfb89 atomic_set(&pool->nr_running, 0); spin_lock_irq(&pool->lock); wake_up_worker(pool); spin_unlock_irq(&pool->lock); } } The resolution is mostly trivial. We want the control flow of the latter with the rename of the former. static void wq_unbind_fn(struct work_struct *work) { ... spin_unlock_irq(&pool->lock); mutex_unlock(&pool->manager_mutex); schedule(); atomic_set(&pool->nr_running, 0); spin_lock_irq(&pool->lock); wake_up_worker(pool); spin_unlock_irq(&pool->lock); } } Signed-off-by: Tejun Heo <tj@kernel.org>
| * Merge branch 'for-3.9-fixes' of ↵Linus Torvalds2013-03-191-19/+25
| |\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull workqueue fix from Tejun Heo: "Lai's patch to fix highly unlikely but still possible workqueue stall during CPU hotunplug." * 'for-3.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: fix possible pool stall bug in wq_unbind_fn()
| | * workqueue: fix possible pool stall bug in wq_unbind_fn()Lai Jiangshan2013-03-091-19/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since multiple pools per cpu have been introduced, wq_unbind_fn() has a subtle bug which may theoretically stall work item processing. The problem is two-fold. * wq_unbind_fn() depends on the worker executing wq_unbind_fn() itself to start unbound chain execution, which works fine when there was only single pool. With multiple pools, only the pool which is running wq_unbind_fn() - the highpri one - is guaranteed to have such kick-off. The other pool could stall when its busy workers block. * The current code is setting WORKER_UNBIND / POOL_DISASSOCIATED of the two pools in succession without initiating work execution inbetween. Because setting the flags requires grabbing assoc_mutex which is held while new workers are created, this could lead to stalls if a pool's manager is waiting for the previous pool's work items to release memory. This is almost purely theoretical tho. Update wq_unbind_fn() such that it sets WORKER_UNBIND / POOL_DISASSOCIATED, goes over schedule() and explicitly kicks off execution for a pool and then moves on to the next one. tj: Updated comments and description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org
| * | workqueue: convert to idr_alloc()Tejun Heo2013-03-131-3/+4
| |/ | | | | | | | | | | | | | | | | idr_get_new*() and friends are about to be deprecated. Convert to the new idr_alloc() interface. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | workqueue: update sysfs interface to reflect NUMA awareness and a kernel ↵Tejun Heo2013-04-011-23/+59
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | param to disable NUMA affinity Unbound workqueues are now NUMA aware. Let's add some control knobs and update sysfs interface accordingly. * Add kernel param workqueue.numa_disable which disables NUMA affinity globally. * Replace sysfs file "pool_id" with "pool_ids" which contain node:pool_id pairs. This change is userland-visible but "pool_id" hasn't seen a release yet, so this is okay. * Add a new sysf files "numa" which can toggle NUMA affinity on individual workqueues. This is implemented as attrs->no_numa whichn is special in that it isn't part of a pool's attributes. It only affects how apply_workqueue_attrs() picks which pools to use. After "pool_ids" change, first_pwq() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: implement NUMA affinity for unbound workqueuesTejun Heo2013-04-011-19/+259
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, an unbound workqueue has single current, or first, pwq (pool_workqueue) to which all new work items are queued. This often isn't optimal on NUMA machines as workers may jump around across node boundaries and work items get assigned to workers without any regard to NUMA affinity. This patch implements NUMA affinity for unbound workqueues. Instead of mapping all entries of numa_pwq_tbl[] to the same pwq, apply_workqueue_attrs() now creates a separate pwq covering the intersecting CPUs for each NUMA node which has online CPUs in @attrs->cpumask. Nodes which don't have intersecting possible CPUs are mapped to pwqs covering whole @attrs->cpumask. As CPUs come up and go down, the pool association is changed accordingly. Changing pool association may involve allocating new pools which may fail. To avoid failing CPU_DOWN, each workqueue always keeps a default pwq which covers whole attrs->cpumask which is used as fallback if pool creation fails during a CPU hotplug operation. This ensures that all work items issued on a NUMA node is executed on the same node as long as the workqueue allows execution on the CPUs of the node. As this maps a workqueue to multiple pwqs and max_active is per-pwq, this change the behavior of max_active. The limit is now per NUMA node instead of global. While this is an actual change, max_active is already per-cpu for per-cpu workqueues and primarily used as safety mechanism rather than for active concurrency control. Concurrency is usually limited from workqueue users by the number of concurrently active work items and this change shouldn't matter much. v2: Fixed pwq freeing in apply_workqueue_attrs() error path. Spotted by Lai. v3: The previous version incorrectly made a workqueue spanning multiple nodes spread work items over all online CPUs when some of its nodes don't have any desired cpus. Reimplemented so that NUMA affinity is properly updated as CPUs go up and down. This problem was spotted by Lai Jiangshan. v4: destroy_workqueue() was putting wq->dfl_pwq and then clearing it; however, wq may be freed at any time after dfl_pwq is put making the clearing use-after-free. Clear wq->dfl_pwq before putting it. v5: apply_workqueue_attrs() was leaking @tmp_attrs, @new_attrs and @pwq_tbl after success. Fixed. Retry loop in wq_update_unbound_numa_attrs() isn't necessary as application of new attrs is excluded via CPU hotplug. Removed. Documentation on CPU affinity guarantee on CPU_DOWN added. All changes are suggested by Lai Jiangshan. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: introduce put_pwq_unlocked()Tejun Heo2013-04-011-13/+23
| | | | | | | | | | | | | | | | | | | | | | | | Factor out lock pool, put_pwq(), unlock sequence into put_pwq_unlocked(). The two existing places are converted and there will be more with NUMA affinity support. This is to prepare for NUMA affinity support for unbound workqueues and doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: introduce numa_pwq_tbl_install()Tejun Heo2013-04-011-9/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Factor out pool_workqueue linking and installation into numa_pwq_tbl[] from apply_workqueue_attrs() into numa_pwq_tbl_install(). link_pwq() is made safe to call multiple times. numa_pwq_tbl_install() links the pwq, installs it into numa_pwq_tbl[] at the specified node and returns the old entry. @last_pwq is removed from link_pwq() as the return value of the new function can be used instead. This is to prepare for NUMA affinity support for unbound workqueues. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: use NUMA-aware allocation for pool_workqueuesTejun Heo2013-04-011-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | Use kmem_cache_alloc_node() with @pool->node instead of kmem_cache_zalloc() when allocating a pool_workqueue so that it's allocated on the same node as the associated worker_pool. As there's no no kmem_cache_zalloc_node(), move zeroing to init_pwq(). This was suggested by Lai Jiangshan. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: break init_and_link_pwq() into two functions and introduce ↵Tejun Heo2013-04-011-29/+49
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | alloc_unbound_pwq() Break init_and_link_pwq() into init_pwq() and link_pwq() and move unbound-workqueue specific handling into apply_workqueue_attrs(). Also, factor out unbound pool and pool_workqueue allocation into alloc_unbound_pwq(). This reorganization is to prepare for NUMA affinity and doesn't introduce any functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: map an unbound workqueues to multiple per-node pool_workqueuesTejun Heo2013-04-011-11/+37
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, an unbound workqueue has only one "current" pool_workqueue associated with it. It may have multple pool_workqueues but only the first pool_workqueue servies new work items. For NUMA affinity, we want to change this so that there are multiple current pool_workqueues serving different NUMA nodes. Introduce workqueue->numa_pwq_tbl[] which is indexed by NUMA node and points to the pool_workqueue to use for each possible node. This replaces first_pwq() in __queue_work() and workqueue_congested(). numa_pwq_tbl[] is currently initialized to point to the same pool_workqueue as first_pwq() so this patch doesn't make any behavior changes. v2: Use rcu_dereference_raw() in unbound_pwq_by_node() as the function may be called only with wq->mutex held. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: move hot fields of workqueue_struct to the endTejun Heo2013-04-011-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move wq->flags and ->cpu_pwqs to the end of workqueue_struct and align them to the cacheline. These two fields are used in the work item issue path and thus hot. The scheduled NUMA affinity support will add dispatch table at the end of workqueue_struct and relocating these two fields will allow us hitting only single cacheline on hot paths. Note that wq->pwqs isn't moved although it currently is being used in the work item issue path for unbound workqueues. The dispatch table mentioned above will replace its use in the issue path, so it will become cold once NUMA support is implemented. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: make workqueue->name[] fixed lenTejun Heo2013-04-011-11/+8
| | | | | | | | | | | | | | | | | | | | Currently workqueue->name[] is of flexible length. We want to use the flexible field for something more useful and there isn't much benefit in allowing arbitrary name length anyway. Make it fixed len capping at 24 bytes. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: add workqueue->unbound_attrsTejun Heo2013-04-011-12/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, when exposing attrs of an unbound workqueue via sysfs, the workqueue_attrs of first_pwq() is used as that should equal the current state of the workqueue. The planned NUMA affinity support will make unbound workqueues make use of multiple pool_workqueues for different NUMA nodes and the above assumption will no longer hold. Introduce workqueue->unbound_attrs which records the current attrs in effect and use it for sysfs instead of first_pwq()->attrs. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: determine NUMA node of workers accourding to the allowed cpumaskTejun Heo2013-04-011-2/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When worker tasks are created using kthread_create_on_node(), currently only per-cpu ones have the matching NUMA node specified. All unbound workers are always created with NUMA_NO_NODE. Now that an unbound worker pool may have an arbitrary cpumask associated with it, this isn't optimal. Add pool->node which is determined by the pool's cpumask. If the pool's cpumask is contained inside a NUMA node proper, the pool is associated with that node, and all workers of the pool are created on that node. This currently only makes difference for unbound worker pools with cpumask contained inside single NUMA node, but this will serve as foundation for making all unbound pools NUMA-affine. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: drop 'H' from kworker names of unbound worker poolsTejun Heo2013-04-011-7/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, all workqueue workers which have negative nice value has 'H' postfixed to their names. This is necessary for per-cpu workers as they use the CPU number instead of pool->id to identify the pool and the 'H' postfix is the only thing distinguishing normal and highpri workers. As workers for unbound pools use pool->id, the 'H' postfix is purely informational. TASK_COMM_LEN is 16 and after the static part and delimiters, there are only five characters left for the pool and worker IDs. We're expecting to have more unbound pools with the scheduled NUMA awareness support. Let's drop the non-essential 'H' postfix from unbound kworker name. While at it, restructure kthread_create*() invocation to help future NUMA related changes. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: add wq_numa_tbl_len and wq_numa_possible_cpumask[]Tejun Heo2013-04-011-0/+46
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Unbound workqueues are going to be NUMA-affine. Add wq_numa_tbl_len and wq_numa_possible_cpumask[] in preparation. The former is the highest NUMA node ID + 1 and the latter is masks of possibles CPUs for each NUMA node. This patch only introduces these. Future patches will make use of them. v2: NUMA initialization move into wq_numa_init(). Also, the possible cpumask array is not created if there aren't multiple nodes on the system. wq_numa_enabled bool added. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: move pwq_pool_locking outside of get/put_unbound_pool()Tejun Heo2013-04-011-14/+22
| | | | | | | | | | | | | | | | | | | | | | | | The scheduled NUMA affinity support for unbound workqueues would need to walk workqueues list and pool related operations on each workqueue. Move wq_pool_mutex locking out of get/put_unbound_pool() to their callers so that pool operations can be performed while walking the workqueues list, which is also protected by wq_pool_mutex. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: fix memory leak in apply_workqueue_attrs()Tejun Heo2013-04-011-3/+8
| | | | | | | | | | | | | | | | apply_workqueue_attrs() wasn't freeing temp attrs variable @new_attrs in its success path. Fix it. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: fix unbound workqueue attrs hashing / comparisonTejun Heo2013-04-011-32/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 29c91e9912b ("workqueue: implement attribute-based unbound worker_pool management") implemented attrs based worker_pool matching. It tried to avoid false negative when comparing cpumasks with custom hash function; unfortunately, the hash and comparison functions fail to ignore CPUs which are not possible. It incorrectly assumed that bitmap_copy() skips leftover bits in the last word of bitmap and cpumask_equal() ignores impossible CPUs. This patch updates attrs->cpumask handling such that impossible CPUs are properly ignored. * Hash and copy functions no longer do anything special. They expect their callers to clear impossible CPUs. * alloc_workqueue_attrs() initializes the cpumask to cpu_possible_mask instead of setting all bits and explicit cpumask_setall() for unbound_std_wq_attrs[] in init_workqueues() is dropped. * apply_workqueue_attrs() is now responsible for ignoring impossible CPUs. It makes a copy of @attrs and clears impossible CPUs before doing anything else. Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: fix race condition in unbound workqueue free pathTejun Heo2013-04-011-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | 8864b4e59 ("workqueue: implement get/put_pwq()") implemented pwq (pool_workqueue) refcnting which frees workqueue when the last pwq goes away. It determined whether it was the last pwq by testing wq->pwqs is empty. Unfortunately, the test was done outside wq->mutex and multiple pwq release could race and try to free wq multiple times leading to oops. Test wq->pwqs emptiness while holding wq->mutex. Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: remove pwq_lock which is no longer usedLai Jiangshan2013-03-261-11/+2
| | | | | | | | | | | | | | | | | | | | | | To simplify locking, the previous patches expanded wq->mutex to protect all fields of each workqueue instance including the pwqs list leaving pwq_lock without any user. Remove the unused pwq_lock. tj: Rebased on top of the current dev branch. Updated description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: protect wq->saved_max_active with wq->mutexLai Jiangshan2013-03-261-17/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We're expanding wq->mutex to cover all fields specific to each workqueue with the end goal of replacing pwq_lock which will make locking simpler and easier to understand. This patch makes wq->saved_max_active protected by wq->mutex instead of pwq_lock. As pwq_lock locking around pwq_adjust_mac_active() is no longer necessary, this patch also replaces pwq_lock lockings of for_each_pwq() around pwq_adjust_max_active() to wq->mutex. tj: Rebased on top of the current dev branch. Updated description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: protect wq->pwqs and iteration with wq->mutexLai Jiangshan2013-03-261-24/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We're expanding wq->mutex to cover all fields specific to each workqueue with the end goal of replacing pwq_lock which will make locking simpler and easier to understand. init_and_link_pwq() and pwq_unbound_release_workfn() already grab wq->mutex when adding or removing a pwq from wq->pwqs list. This patch makes it official that the list is wq->mutex protected for writes and updates readers accoridingly. Explicit IRQ toggles for sched-RCU read-locking in flush_workqueue_prep_pwqs() and drain_workqueues() are removed as the surrounding wq->mutex can provide sufficient synchronization. Also, assert_rcu_or_pwq_lock() is renamed to assert_rcu_or_wq_mutex() and checks for wq->mutex too. pwq_lock locking and assertion are not removed by this patch and a couple of for_each_pwq() iterations are still protected by it. They'll be removed by future patches. tj: Rebased on top of the current dev branch. Updated description. Folded in assert_rcu_or_wq_mutex() renaming from a later patch along with associated comment updates. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: protect wq->nr_drainers and ->flags with wq->mutexLai Jiangshan2013-03-261-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | We're expanding wq->mutex to cover all fields specific to each workqueue with the end goal of replacing pwq_lock which will make locking simpler and easier to understand. wq->nr_drainers and ->flags are specific to each workqueue. Protect ->nr_drainers and ->flags with wq->mutex instead of pool_mutex. tj: Rebased on top of the current dev branch. Updated description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: rename wq->flush_mutex to wq->mutexLai Jiangshan2013-03-261-26/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently pwq->flush_mutex protects many fields of a workqueue including, especially, the pwqs list. We're going to expand this mutex to protect most of a workqueue and eventually replace pwq_lock, which will make locking simpler and easier to understand. Drop the "flush_" prefix in preparation. This patch is pure rename. tj: Rebased on top of the current dev branch. Updated description. Use WQ: and WR: instead of Q: and QR: for synchronization labels. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: rename wq_mutex to wq_pool_mutexLai Jiangshan2013-03-261-54/+55
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | wq->flush_mutex will be renamed to wq->mutex and cover all fields specific to each workqueue and eventually replace pwq_lock, which will make locking simpler and easier to understand. Rename wq_mutex to wq_pool_mutex to avoid confusion with wq->mutex. After the scheduled changes, wq_pool_mutex won't be protecting anything specific to each workqueue instance anyway. This patch is pure rename. tj: s/wqs_mutex/wq_pool_mutex/. Rewrote description. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: avoid false negative in assert_manager_or_pool_lock()Lai Jiangshan2013-03-201-1/+2
| | | | | | | | | | | | | | | | | | If lockdep complains something for other subsystem, lockdep_is_held() can be false negative, so we need to also test debug_locks before triggering WARN. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: use rcu_read_lock_sched() instead for accessing pwq in RCULai Jiangshan2013-03-201-5/+5
| | | | | | | | | | | | | | | | rcu_read_lock_sched() is better than preempt_disable() if the code is protected by RCU_SCHED. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: kick a worker in pwq_adjust_max_active()Lai Jiangshan2013-03-201-7/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If pwq_adjust_max_active() changes max_active from 0 to saved_max_active, it needs to wakeup worker. This is already done by thaw_workqueues(). If pwq_adjust_max_active() increases max_active for an unbound wq, while not strictly necessary for correctness, it's still desirable to wake up a worker so that the requested concurrency level is reached sooner. Move wake_up_worker() call from thaw_workqueues() to pwq_adjust_max_active() so that it can handle both of the above two cases. This also makes thaw_workqueues() simpler. tj: Updated comments and description. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: simplify current_is_workqueue_rescuer()Lai Jiangshan2013-03-201-1/+1
| | | | | | | | | | | | | | | | | | | | We can test worker->recue_wq instead of reaching into current_pwq->wq->rescuer and then comparing it to self. tj: Commit message. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: add missing POOL_FREEZINGLai Jiangshan2013-03-201-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | get_unbound_pool() forgot to set POOL_FREEZING if workqueue_freezing is set and a new pool could go out of sync with the global freezing state. Fix it by adding POOL_FREEZING if workqueue_freezing. wq_mutex is already held so no further locking is necessary. This also removes the unused static variable warning when !CONFIG_FREEZER. tj: Updated commit message. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | workqueue: restore CPU affinity of unbound workers on CPU_ONLINETejun Heo2013-03-191-5/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the recent addition of the custom attributes support, unbound pools may have allowed cpumask which isn't full. As long as some of CPUs in the cpumask are online, its workers will maintain cpus_allowed as set on worker creation; however, once no online CPU is left in cpus_allowed, the scheduler will reset cpus_allowed of any workers which get scheduled so that they can execute. To remain compliant to the user-specified configuration, CPU affinity needs to be restored when a CPU becomes online for an unbound pool which doesn't currently have any online CPUs before. This patch implement restore_unbound_workers_cpumask(), which is called from CPU_ONLINE for all unbound pools, checks whether the coming up CPU is the first allowed online one, and, if so, invokes set_cpus_allowed_ptr() with the configured cpumask on all workers. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: directly restore CPU affinity of workers from CPU_ONLINETejun Heo2013-03-191-128/+64
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rebinding workers of a per-cpu pool after a CPU comes online involves a lot of back-and-forth mostly because only the task itself could adjust CPU affinity if PF_THREAD_BOUND was set. As CPU_ONLINE itself couldn't adjust affinity, it had to somehow coerce the workers themselves to perform set_cpus_allowed_ptr(). Due to the various states a worker can be in, this led to three different paths a worker may be rebound. worker->rebind_work is queued to busy workers. Idle ones are signaled by unlinking worker->entry and call idle_worker_rebind(). The manager isn't covered by either and implements its own mechanism. PF_THREAD_BOUND has been relaced with PF_NO_SETAFFINITY and CPU_ONLINE itself now can manipulate CPU affinity of workers. This patch replaces the existing rebind mechanism with direct one where CPU_ONLINE iterates over all workers using for_each_pool_worker(), restores CPU affinity, and clears WORKER_UNBOUND. There are a couple subtleties. All bound idle workers should have their runqueues set to that of the bound CPU; however, if the target task isn't running, set_cpus_allowed_ptr() just updates the cpus_allowed mask deferring the actual migration to when the task wakes up. This is worked around by waking up idle workers after restoring CPU affinity before any workers can become bound. Another subtlety is stems from matching @pool->nr_running with the number of running unbound workers. While DISASSOCIATED, all workers are unbound and nr_running is zero. As workers become bound again, nr_running needs to be adjusted accordingly; however, there is no good way to tell whether a given worker is running without poking into scheduler internals. Instead of clearing UNBOUND directly, rebind_workers() replaces UNBOUND with another new NOT_RUNNING flag - REBOUND, which will later be cleared by the workers themselves while preparing for the next round of work item execution. The only change needed for the workers is clearing REBOUND along with PREP. * This patch leaves for_each_busy_worker() without any user. Removed. * idle_worker_rebind(), busy_worker_rebind_fn(), worker->rebind_work and rebind logic in manager_workers() removed. * worker_thread() now looks at WORKER_DIE instead of testing whether @worker->entry is empty to determine whether it needs to do something special as dying is the only special thing now. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
* | workqueue: relocate rebind_workers()Tejun Heo2013-03-191-71/+71
| | | | | | | | | | | | | | | | | | | | | | rebind_workers() will be reimplemented in a way which makes it mostly decoupled from the rest of worker management. Move rebind_workers() so that it's located with other CPU hotplug related functions. This patch is pure function relocation. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-26 10:03:01 +0100