Re: [PATCH v3 5/6] sched/wait: Add wait_event_state()

Peter Zijlstra
2022-09-06T11:09:12Z

On Sun, Sep 04, 2022 at 11:54:57AM +0200, Ingo Molnar wrote:
> > +/**
> > + * wait_event_state - sleep until a condition gets true
> > + * @wq_head: the waitqueue to wait on
> > + * @condition: a C expression for the event to wait for
> > + * @state: state to sleep in
> > + *
> > + * The process is put to sleep (@state) until the @condition evaluates to true
> > + * or a signal is received. The @condition is checked each time the waitqueue
> > + * @wq_head is woken up.
>
> Documentation inconsistency nit: if TASK_INTERRUPTIBLE isn't in @state then
> we won't wake up when a signal is received. This probably got copy-pasted
> from a signal variant.
>
> > + *
> > + * wake_up() has to be called after changing any variable that could
> > + * change the result of the wait condition.
> > + *
> > + * The function will return -ERESTARTSYS if it was interrupted by a
> > + * signal and 0 if @condition evaluated to true.
>
> That's not unconditionally true either if !TASK_INTERRUPTIBLE.

--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -942,14 +942,14 @@ extern int do_wait_intr_irq(wait_queue_h
* @state: state to sleep in
*
* The process is put to sleep (@state) until the @condition evaluates to true
- * or a signal is received. The @condition is checked each time the waitqueue
- * @wq_head is woken up.
+ * or a signal is received (when allowed by @state). The @condition is checked
+ * each time the waitqueue @wq_head is woken up.
*
* wake_up() has to be called after changing any variable that could
* change the result of the wait condition.
*
- * The function will return -ERESTARTSYS if it was interrupted by a
- * signal and 0 if @condition evaluated to true.
+ * The function will return -ERESTARTSYS if it was interrupted by a signal
+ * (when allowed by @state) and 0 if @condition evaluated to true.
*/
#define wait_event_state(wq_head, condition, state) \
({ \

> > +#define wait_event_state(wq_head, condition, state) \
> > +({ \
> > + int __ret = 0; \
> > + might_sleep(); \
>
> Very small style consistency nit, the above should have a newline after
> local variables:
>
> > +#define wait_event_state(wq_head, condition, state) \
> > +({ \
> > + int __ret = 0; \
> > + \
> > + might_sleep(); \
>
> Like most (but not all ... :-/ ) of the existing primitives have.

Yeah, I'm going to leave it as is.