Messages in this thread |  | | Date | Mon, 13 Jan 2014 11:41:18 -0500 | From | Waiman Long <> | Subject | Re: [PATCH v8 4/4] qrwlock: Use smp_store_release() in write_unlock() |
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On 01/12/2014 09:47 PM, 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,
I found out that the build failure was caused by the fact that the __native_word() macro (used internally by compiletime_assert_atomic()) allows only a size of 4 or 8 for x86-64. The data type that I used is a byte. Is there a reason why byte and short are not considered native?
-Longman
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