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rcuwait: Introduce rcuwait_active() 

This call is lockless and thus should not be trusted blindly.
For example, the return value of rcuwait_wakeup() should be used to
track whether a process was woken up.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Message-Id: <20200424054837.5138-5-dave@stgolabs.net>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Davidlohr Bueso 2020-04-23 22:48:36 -07:00 committed by Paolo Bonzini
parent 5c21f7b322
commit 191a43be61
1 changed files with 9 additions and 0 deletions
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9
include/linux/rcuwait.h
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@ -25,6 +25,15 @@ static inline void rcuwait_init(struct rcuwait *w)
w->task = NULL;
}
/*
* Note: this provides no serialization and, just as with waitqueues,
* requires care to estimate as to whether or not the wait is active.
*/
static inline int rcuwait_active(struct rcuwait *w)
{
return !!rcu_dereference(w->task);
}
extern int rcuwait_wake_up(struct rcuwait *w);
/*