linux/kernel/workqueue.c, branch v6.17

Merge tag 'wq-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2025-07-31T22:40:22Z

Pull workqueue updates from Tejun Heo: - Prepare for defaulting to unbound workqueue. A separate branch was created to ease pulling in from other trees but none of the conversions have landed yet - Memory allocation profiling support added - Misc changes * tag 'wq-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: Use atomic_try_cmpxchg_relaxed() in tryinc_node_nr_active() workqueue: Remove unused work_on_cpu_safe workqueue: Add new WQ_PERCPU flag workqueue: Add system_percpu_wq and system_dfl_wq workqueue: Basic memory allocation profiling support workqueue: fix opencoded cpumask_next_and_wrap() in wq_select_unbound_cpu()

workqueue: Use atomic_try_cmpxchg_relaxed() in tryinc_node_nr_active()

2025-07-17T18:14:50Z

Use try_cmpxchg() family of locking primitives instead of cmpxchg(*ptr, old, new) == old. The x86 CMPXCHG instruction returns success in the ZF flag, so this change saves a compare after CMPXCHG (and related move instruction in front of CMPXCHG). Also, try_cmpxchg() implicitly assigns old *ptr value to "old" when CMPXCHG fails. There is no need to re-read the value in the loop. The generated assembly improves from: 3f7: 44 8b 0a mov (%rdx),%r9d 3fa: eb 12 jmp 40e <...> 3fc: 8d 79 01 lea 0x1(%rcx),%edi 3ff: 89 c8 mov %ecx,%eax 401: f0 0f b1 7a 04 lock cmpxchg %edi,0x4(%rdx) 406: 39 c1 cmp %eax,%ecx 408: 0f 84 83 00 00 00 je 491 <...> 40e: 8b 4a 04 mov 0x4(%rdx),%ecx 411: 41 39 c9 cmp %ecx,%r9d 414: 7f e6 jg 3fc <...> to: 256b: 45 8b 08 mov (%r8),%r9d 256e: 41 8b 40 04 mov 0x4(%r8),%eax 2572: 41 39 c1 cmp %eax,%r9d 2575: 7e 10 jle 2587 <...> 2577: 8d 78 01 lea 0x1(%rax),%edi 257a: f0 41 0f b1 78 04 lock cmpxchg %edi,0x4(%r8) 2580: 75 f0 jne 2572 <...> No functional change intended. Signed-off-by: Uros Bizjak Cc: Tejun Heo Cc: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: Remove unused work_on_cpu_safe

2025-06-23T18:07:06Z

The last use of the work_on_cpu_safe() macro was removed recently by commit 9cda46babdfe ("crypto: n2 - remove Niagara2 SPU driver") Remove it, and the work_on_cpu_safe_key() function it calls. Signed-off-by: Dr. David Alan Gilbert Signed-off-by: Tejun Heo

workqueue: Initialize wq_isolated_cpumask in workqueue_init_early()

2025-06-17T18:58:29Z

Now when isolcpus is enabled via the cmdline, wq_isolated_cpumask does not include these isolated CPUs, even wq_unbound_cpumask has already excluded them. It is only when we successfully configure an isolate cpuset partition that wq_isolated_cpumask gets overwritten by workqueue_unbound_exclude_cpumask(), including both the cmdline-specified isolated CPUs and the isolated CPUs within the cpuset partitions. Fix this issue by initializing wq_isolated_cpumask properly in workqueue_init_early(). Fixes: fe28f631fa94 ("workqueue: Add workqueue_unbound_exclude_cpumask() to exclude CPUs from wq_unbound_cpumask") Signed-off-by: Chuyi Zhou Reviewed-by: Waiman Long Signed-off-by: Tejun Heo

Merge branch 'WQ_PERCPU' into for-6.17

2025-06-17T18:52:50Z

workqueue: Add system_percpu_wq and system_dfl_wq

2025-06-17T18:51:34Z

Currently, if a user enqueue a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistentcy cannot be addressed without refactoring the API. system_wq is a per-CPU worqueue, yet nothing in its name tells about that CPU affinity constraint, which is very often not required by users. Make it clear by adding a system_percpu_wq. system_unbound_wq should be the default workqueue so as not to enforce locality constraints for random work whenever it's not required. Adding system_dfl_wq to encourage its use when unbound work should be used. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Signed-off-by: Tejun Heo

workqueue: Basic memory allocation profiling support

2025-06-16T18:01:45Z

Hook alloc_workqueue and alloc_workqueue_attrs() so that they're accounted to the callsite. Since we're doing allocations on behalf of another subsystem, this helps when using memory allocation profiling to check for leaks. Cc: Tejun Heo Cc: Lai Jiangshan Signed-off-by: Kent Overstreet Signed-off-by: Tejun Heo

workqueue: fix opencoded cpumask_next_and_wrap() in wq_select_unbound_cpu()

2025-06-09T18:25:17Z

The dedicated helper is more verbose and effective comparing to cpumask_first() followed by cpumask_next(). Signed-off-by: Yury Norov [NVIDIA] Signed-off-by: Tejun Heo

treewide, timers: Rename from_timer() to timer_container_of()

2025-06-08T07:07:37Z

Move this API to the canonical timer_*() namespace. [ tglx: Redone against pre rc1 ] Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com

Merge tag 'wq-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2025-05-28T03:49:06Z

Pull workqueue updates from Tejun Heo: "Fix statistic update race condition and a couple documentation updates" * tag 'wq-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: fix typo in comment workqueue: Fix race condition in wq->stats incrementation workqueue: Better document teardown for delayed_work