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| author | Davidlohr Bueso <dave@stgolabs.net> | 2015-02-22 19:31:41 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-02-24 08:44:16 +0100 |
| commit | 4d3199e4ca8e6670b54dc5ee070ffd54385988e9 (patch) | |
| tree | 5529bcb16c3217c02416e0d17d7c28f277c63581 /kernel/locking/mcs_spinlock.h | |
| parent | 2ae79026818e7d49fead82b79b1a543e3b9c8a23 (diff) | |
| download | op-kernel-dev-4d3199e4ca8e6670b54dc5ee070ffd54385988e9.zip op-kernel-dev-4d3199e4ca8e6670b54dc5ee070ffd54385988e9.tar.gz | |
locking: Remove ACCESS_ONCE() usage
With the new standardized functions, we can replace all
ACCESS_ONCE() calls across relevant locking - this includes
lockref and seqlock while at it.
ACCESS_ONCE() does not work reliably on non-scalar types.
For example gcc 4.6 and 4.7 might remove the volatile tag
for such accesses during the SRA (scalar replacement of
aggregates) step:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
Update the new calls regardless of if it is a scalar type,
this is cleaner than having three alternatives.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1424662301.6539.18.camel@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking/mcs_spinlock.h')
| -rw-r--r-- | kernel/locking/mcs_spinlock.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/locking/mcs_spinlock.h b/kernel/locking/mcs_spinlock.h index d1fe2ba..75e114b 100644 --- a/kernel/locking/mcs_spinlock.h +++ b/kernel/locking/mcs_spinlock.h @@ -78,7 +78,7 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) */ return; } - ACCESS_ONCE(prev->next) = node; + WRITE_ONCE(prev->next, node); /* Wait until the lock holder passes the lock down. */ arch_mcs_spin_lock_contended(&node->locked); @@ -91,7 +91,7 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) static inline void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node) { - struct mcs_spinlock *next = ACCESS_ONCE(node->next); + struct mcs_spinlock *next = READ_ONCE(node->next); if (likely(!next)) { /* @@ -100,7 +100,7 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node) if (likely(cmpxchg(lock, node, NULL) == node)) return; /* Wait until the next pointer is set */ - while (!(next = ACCESS_ONCE(node->next))) + while (!(next = READ_ONCE(node->next))) cpu_relax_lowlatency(); } |
