Messages in this thread | | | Date | Sun, 12 Jan 2014 19:49:57 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH v8 4/4] qrwlock: Use smp_store_release() in write_unlock() |
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On Mon, Jan 13, 2014 at 10:47:36AM +0800, Daniel J Blueman wrote: > On Thursday, 9 January 2014 01:10:03 UTC+8, Waiman Long wrote: > > This patch modifies the queue_write_unlock() function to use the > > new smp_store_release() function in another pending patch. It also > > removes the temporary implementation of smp_load_acquire() and > > smp_store_release() function in qrwlock.c. > > > > This patch should only be merged if PeterZ's linux-arch patch patch > > was merged. > > > > Signed-off-by: Waiman Long <Waiman.Long@hp.com> > > Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > --- > > include/asm-generic/qrwlock.h | 4 +--- > > kernel/locking/qrwlock.c | 34 ---------------------------------- > > 2 files changed, 1 insertions(+), 37 deletions(-) > > > > diff --git a/include/asm-generic/qrwlock.h > b/include/asm-generic/qrwlock.h > > index 2b9a7b4..4d4bd04 100644 > > --- a/include/asm-generic/qrwlock.h > > +++ b/include/asm-generic/qrwlock.h > > @@ -179,9 +179,7 @@ static inline void queue_write_unlock(struct > qrwlock *lock) > > /* > > * Make sure that none of the critical section will be leaked out. > > */ > > - smp_mb__before_clear_bit(); > > - ACCESS_ONCE(lock->cnts.writer) = 0; > > - smp_mb__after_clear_bit(); > > + smp_store_release(&lock->cnts.writer, 0) > > This will fail compilation, so probably needs further testing with > Peter's load_acquire/store_release barrier patches.
Peter's patch just hit -tip, so this should be esay to do. In Waiman's defense, he does call attention to this in the commit log.
Thanx, Paul
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