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Workqueue fixes for v5.19-rc1

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Tetsuo's patch to trigger build warnings if system-wide wq's are flushed
 along with a TP type update and trivial comment update.
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Merge tag 'wq-for-5.19-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue fixes from Tejun Heo:
 "Tetsuo's patch to trigger build warnings if system-wide wq's are
  flushed along with a TP type update and trivial comment update"

* tag 'wq-for-5.19-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Switch to new kerneldoc syntax for named variable macro argument
  workqueue: Fix type of cpu in trace event
  workqueue: Wrap flush_workqueue() using a macro
This commit is contained in:
Linus Torvalds 2022-06-12 11:16:00 -07:00
commit b0cb8db396
3 changed files with 73 additions and 17 deletions
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66
include/linux/workqueue.h
View file

@ -406,7 +406,7 @@ alloc_workqueue(const char *fmt, unsigned int flags, int max_active, ...);
* alloc_ordered_workqueue - allocate an ordered workqueue
* @fmt: printf format for the name of the workqueue
* @flags: WQ_* flags (only WQ_FREEZABLE and WQ_MEM_RECLAIM are meaningful)
* @args...: args for @fmt
* @args: args for @fmt
*
* Allocate an ordered workqueue. An ordered workqueue executes at
* most one work item at any given time in the queued order. They are
@ -445,7 +445,7 @@ extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
struct delayed_work *dwork, unsigned long delay);
extern bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork);
extern void flush_workqueue(struct workqueue_struct *wq);
extern void __flush_workqueue(struct workqueue_struct *wq);
extern void drain_workqueue(struct workqueue_struct *wq);
extern int schedule_on_each_cpu(work_func_t func);
@ -563,15 +563,23 @@ static inline bool schedule_work(struct work_struct *work)
return queue_work(system_wq, work);
}
/*
* Detect attempt to flush system-wide workqueues at compile time when possible.
*
* See https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jp
* for reasons and steps for converting system-wide workqueues into local workqueues.
*/
extern void __warn_flushing_systemwide_wq(void)
__compiletime_warning("Please avoid flushing system-wide workqueues.");
/**
* flush_scheduled_work - ensure that any scheduled work has run to completion.
*
* Forces execution of the kernel-global workqueue and blocks until its
* completion.
*
* Think twice before calling this function! It's very easy to get into
* trouble if you don't take great care. Either of the following situations
* will lead to deadlock:
* It's very easy to get into trouble if you don't take great care.
* Either of the following situations will lead to deadlock:
*
* One of the work items currently on the workqueue needs to acquire
* a lock held by your code or its caller.
@ -586,11 +594,51 @@ static inline bool schedule_work(struct work_struct *work)
* need to know that a particular work item isn't queued and isn't running.
* In such cases you should use cancel_delayed_work_sync() or
* cancel_work_sync() instead.
*
* Please stop calling this function! A conversion to stop flushing system-wide
* workqueues is in progress. This function will be removed after all in-tree
* users stopped calling this function.
*/
static inline void flush_scheduled_work(void)
{
flush_workqueue(system_wq);
}
/*
* The background of commit 771c035372a036f8 ("deprecate the
* '__deprecated' attribute warnings entirely and for good") is that,
* since Linus builds all modules between every single pull he does,
* the standard kernel build needs to be _clean_ in order to be able to
* notice when new problems happen. Therefore, don't emit warning while
* there are in-tree users.
*/
#define flush_scheduled_work() \
({ \
if (0) \
__warn_flushing_systemwide_wq(); \
__flush_workqueue(system_wq); \
})
/*
* Although there is no longer in-tree caller, for now just emit warning
* in order to give out-of-tree callers time to update.
*/
#define flush_workqueue(wq) \
({ \
struct workqueue_struct *_wq = (wq); \
\
if ((__builtin_constant_p(_wq == system_wq) && \
_wq == system_wq) || \
(__builtin_constant_p(_wq == system_highpri_wq) && \
_wq == system_highpri_wq) || \
(__builtin_constant_p(_wq == system_long_wq) && \
_wq == system_long_wq) || \
(__builtin_constant_p(_wq == system_unbound_wq) && \
_wq == system_unbound_wq) || \
(__builtin_constant_p(_wq == system_freezable_wq) && \
_wq == system_freezable_wq) || \
(__builtin_constant_p(_wq == system_power_efficient_wq) && \
_wq == system_power_efficient_wq) || \
(__builtin_constant_p(_wq == system_freezable_power_efficient_wq) && \
_wq == system_freezable_power_efficient_wq)) \
__warn_flushing_systemwide_wq(); \
__flush_workqueue(_wq); \
})
/**
* schedule_delayed_work_on - queue work in global workqueue on CPU after delay