user/sven/linux.git/kernel/workqueue.c, branch v5.8.10

maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault

2020-06-17T17:57:41Z

Better describe what these functions do. Suggested-by: Linus Torvalds Signed-off-by: Christoph Hellwig Signed-off-by: Linus Torvalds

workqueue: use BUILD_BUG_ON() for compile time test instead of WARN_ON()

2020-06-01T15:02:42Z

Any runtime WARN_ON() has to be fixed, and BUILD_BUG_ON() can help you nitice it earlier. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: remove useless unlock() and lock() in series

2020-05-29T14:25:23Z

This is no point to unlock() and then lock() the same mutex back to back. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: void unneeded requeuing the pwq in rescuer thread

2020-05-29T14:22:10Z

008847f66c3 ("workqueue: allow rescuer thread to do more work.") made the rescuer worker requeue the pwq immediately if there may be more work items which need rescuing instead of waiting for the next mayday timer expiration. Unfortunately, it checks only whether the pool needs help from rescuers, but it doesn't check whether the pwq has work items in the pool (the real reason that this rescuer can help for the pool). The patch adds the check and void unneeded requeuing. Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: Convert the pool::lock and wq_mayday_lock to raw_spinlock_t

2020-05-29T14:03:47Z

The workqueue code has it's internal spinlocks (pool::lock), which are acquired on most workqueue operations. These spinlocks are converted to 'sleeping' spinlocks on a RT-kernel. Workqueue functions can be invoked from contexts which are truly atomic even on a PREEMPT_RT enabled kernel. Taking sleeping locks from such contexts is forbidden. The pool::lock hold times are bound and the code sections are relatively short, which allows to convert pool::lock and as a consequence wq_mayday_lock to raw spinlocks which are truly spinning locks even on a PREEMPT_RT kernel. With the previous conversion of the manager waitqueue to a simple waitqueue workqueues are now fully RT compliant. Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: Use rcuwait for wq_manager_wait

2020-05-29T14:00:35Z

The workqueue code has it's internal spinlock (pool::lock) and also implicit spinlock usage in the wq_manager waitqueue. These spinlocks are converted to 'sleeping' spinlocks on a RT-kernel. Workqueue functions can be invoked from contexts which are truly atomic even on a PREEMPT_RT enabled kernel. Taking sleeping locks from such contexts is forbidden. pool::lock can be converted to a raw spinlock as the lock held times are short. But the workqueue manager waitqueue is handled inside of pool::lock held regions which again violates the lock nesting rules of raw and regular spinlocks. The manager waitqueue has no special requirements like custom wakeup callbacks or mass wakeups. While it does not use exclusive wait mode explicitly there is no strict requirement to queue the waiters in a particular order as there is only one waiter at a time. This allows to replace the waitqueue with rcuwait which solves the locking problem because rcuwait relies on existing locking. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Tejun Heo

workqueue: Remove unnecessary kfree() call in rcu_free_wq()

2020-05-27T13:52:41Z

The data structure member "wq->rescuer" was reset to a null pointer in one if branch. It was passed to a call of the function "kfree" in the callback function "rcu_free_wq" (which was eventually executed). The function "kfree" does not perform more meaningful data processing for a passed null pointer (besides immediately returning from such a call). Thus delete this function call which became unnecessary with the referenced software update. Fixes: def98c84b6cd ("workqueue: Fix spurious sanity check failures in destroy_workqueue()") Suggested-by: Markus Elfring Signed-off-by: Zhang Qiang Signed-off-by: Tejun Heo

workqueue: Fix an use after free in init_rescuer()

2020-05-11T14:25:42Z

We need to preserve error code before freeing "rescuer". Fixes: f187b6974f6df ("workqueue: Use IS_ERR and PTR_ERR instead of PTR_ERR_OR_ZERO.") Signed-off-by: Dan Carpenter Reviewed-by: Lai Jiangshan Signed-off-by: Tejun Heo

workqueue: Use IS_ERR and PTR_ERR instead of PTR_ERR_OR_ZERO.

2020-05-05T15:56:07Z

Replace inline function PTR_ERR_OR_ZERO with IS_ERR and PTR_ERR to remove redundant parameter definitions and checks. Reduce code size. Before: text data bss dec hex filename 47510 5979 840 54329 d439 kernel/workqueue.o After: text data bss dec hex filename 47474 5979 840 54293 d415 kernel/workqueue.o Signed-off-by: Sean Fu Signed-off-by: Tejun Heo

workqueue: Remove the warning in wq_worker_sleeping()

2020-04-08T09:35:20Z

The kernel test robot triggered a warning with the following race: task-ctx A interrupt-ctx B worker -> process_one_work() -> work_item() -> schedule(); -> sched_submit_work() -> wq_worker_sleeping() -> ->sleeping = 1 atomic_dec_and_test(nr_running) __schedule(); *interrupt* async_page_fault() -> local_irq_enable(); -> schedule(); -> sched_submit_work() -> wq_worker_sleeping() -> if (WARN_ON(->sleeping)) return -> __schedule() -> sched_update_worker() -> wq_worker_running() -> atomic_inc(nr_running); -> ->sleeping = 0; -> sched_update_worker() -> wq_worker_running() if (!->sleeping) return In this context the warning is pointless everything is fine. An interrupt before wq_worker_sleeping() will perform the ->sleeping assignment (0 -> 1 > 0) twice. An interrupt after wq_worker_sleeping() will trigger the warning and nr_running will be decremented (by A) and incremented once (only by B, A will skip it). This is the case until the ->sleeping is zeroed again in wq_worker_running(). Remove the WARN statement because this condition may happen. Document that preemption around wq_worker_sleeping() needs to be disabled to protect ->sleeping and not just as an optimisation. Fixes: 6d25be5782e48 ("sched/core, workqueues: Distangle worker accounting from rq lock") Reported-by: kernel test robot Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Cc: Tejun Heo Link: https://lkml.kernel.org/r/20200327074308.GY11705@shao2-debian