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author | Mikael Pettersson <mikpe@it.uu.se> | 2011-08-15 10:11:50 +0000 |
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committer | David S. Miller <davem@davemloft.net> | 2011-08-15 14:35:19 -0700 |
commit | 3f6aa0b113846a8628baa649af422cfc6fb1d786 (patch) | |
tree | 5b3d1f9b112a779dab37db5f685c24e5e857df96 /tools/power | |
parent | a0fba3eb059e73fed2d376a901f8117734c12f1f (diff) |
sparc32: unbreak arch_write_unlock()
The sparc32 version of arch_write_unlock() is just a plain assignment.
Unfortunately this allows the compiler to schedule side-effects in a
protected region to occur after the HW-level unlock, which is broken.
E.g., the following trivial test case gets miscompiled:
#include <linux/spinlock.h>
rwlock_t lock;
int counter;
void foo(void) { write_lock(&lock); ++counter; write_unlock(&lock); }
Fixed by adding a compiler memory barrier to arch_write_unlock(). The
sparc64 version combines the barrier and assignment into a single asm(),
and implements the operation as a static inline, so that's what I did too.
Compile-tested with sparc32_defconfig + CONFIG_SMP=y.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'tools/power')
0 files changed, 0 insertions, 0 deletions