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| author |   Davidlohr Bueso <dave@stgolabs.net> | 2020-04-23 22:48:35 -0700 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2020-05-13 12:14:53 -0400 |
| commit | 5c21f7b322cb9fcb97f2e22f5976a0ae8dd71354 (patch) | |
| tree | 72ec9240d0723c39b70672ccfc1c63a33b4fd094 /include/linux/rcuwait.h | |
| parent | rcuwait: Let rcuwait_wake_up() return whether or not a task was awoken (diff) | |
| download | linux-dev-5c21f7b322cb9fcb97f2e22f5976a0ae8dd71354.tar.xz linux-dev-5c21f7b322cb9fcb97f2e22f5976a0ae8dd71354.zip | |
rcuwait: Introduce prepare_to and finish_rcuwait
This allows further flexibility for some callers to implement
ad-hoc versions of the generic rcuwait_wait_event(). For example,
kvm will need this to maintain tracing semantics. The naming
is of course similar to what waitqueue apis offer.
Also go ahead and make use of rcu_assign_pointer() for both task
writes as it will make the __rcu sparse people happy - this will
be the special nil case, thus no added serialization.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Message-Id: <20200424054837.5138-4-dave@stgolabs.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/linux/rcuwait.h')
| -rw-r--r-- | include/linux/rcuwait.h | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/include/linux/rcuwait.h b/include/linux/rcuwait.h index 6ebb23258a27..45bc6604e9b1 100644 --- a/include/linux/rcuwait.h +++ b/include/linux/rcuwait.h @@ -29,12 +29,25 @@ extern int rcuwait_wake_up(struct rcuwait *w); /* * The caller is responsible for locking around rcuwait_wait_event(), - * such that writes to @task are properly serialized. + * and [prepare_to/finish]_rcuwait() such that writes to @task are + * properly serialized. */ + +static inline void prepare_to_rcuwait(struct rcuwait *w) +{ + rcu_assign_pointer(w->task, current); +} + +static inline void finish_rcuwait(struct rcuwait *w) +{ + rcu_assign_pointer(w->task, NULL); + __set_current_state(TASK_RUNNING); +} + #define rcuwait_wait_event(w, condition, state) \ ({ \ int __ret = 0; \ - rcu_assign_pointer((w)->task, current); \ + prepare_to_rcuwait(w); \ for (;;) { \ /* \ * Implicit barrier (A) pairs with (B) in \ @@ -51,9 +64,7 @@ extern int rcuwait_wake_up(struct rcuwait *w); \ schedule(); \ } \ - \ - WRITE_ONCE((w)->task, NULL); \ - __set_current_state(TASK_RUNNING); \ + finish_rcuwait(w); \ __ret; \ }) |