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author | Andrea Parri <andrea.parri@amarulasolutions.com> | 2018-07-16 11:06:03 -0700 |
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committer | Ingo Molnar <mingo@kernel.org> | 2018-07-17 09:30:34 +0200 |
commit | 7696f9910a9a40b8a952f57d3428515fabd2d889 (patch) | |
tree | 194b3c37bfd2a14378cb59bab3655ee6d0115cfb /kernel/sched/completion.c | |
parent | 3d85b2703783636366560c94842affd8608ec9d1 (diff) | |
download | linux-7696f9910a9a40b8a952f57d3428515fabd2d889.tar.gz |
sched/Documentation: Update wake_up() & co. memory-barrier guarantees
Both the implementation and the users' expectation [1] for the various wakeup primitives have evolved over time, but the documentation has not kept up with these changes: brings it into 2018. [1] http://lkml.kernel.org/r/20180424091510.GB4064@hirez.programming.kicks-ass.net Also applied feedback from Alan Stern. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Akira Yokosawa <akiyks@gmail.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Daniel Lustig <dlustig@nvidia.com> Cc: David Howells <dhowells@redhat.com> Cc: Jade Alglave <j.alglave@ucl.ac.uk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luc Maranget <luc.maranget@inria.fr> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arch@vger.kernel.org Cc: parri.andrea@gmail.com Link: http://lkml.kernel.org/r/20180716180605.16115-12-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/completion.c')
-rw-r--r-- | kernel/sched/completion.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c index e426b0cb9ac6..a1ad5b7d5521 100644 --- a/kernel/sched/completion.c +++ b/kernel/sched/completion.c @@ -22,8 +22,8 @@ * * See also complete_all(), wait_for_completion() and related routines. * - * It may be assumed that this function implies a write memory barrier before - * changing the task state if and only if any tasks are woken up. + * If this function wakes up a task, it executes a full memory barrier before + * accessing the task state. */ void complete(struct completion *x) { @@ -44,8 +44,8 @@ EXPORT_SYMBOL(complete); * * This will wake up all threads waiting on this particular completion event. * - * It may be assumed that this function implies a write memory barrier before - * changing the task state if and only if any tasks are woken up. + * If this function wakes up a task, it executes a full memory barrier before + * accessing the task state. * * Since complete_all() sets the completion of @x permanently to done * to allow multiple waiters to finish, a call to reinit_completion() |