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| author | Joern Engel <joern@logfs.org> | 2014-09-16 16:23:12 -0400 |
|---|---|---|
| committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2014-10-01 14:39:06 -0700 |
| commit | 33940d09937276cd3c81f2874faf43e37c2db0e2 (patch) | |
| tree | 2c3043e6902ee4e8e23b947f2e30e50967e99c5b /include/target | |
| parent | 74ed7e62289dc6d388996d7c8f89c2e7e95b9657 (diff) | |
| download | linux-33940d09937276cd3c81f2874faf43e37c2db0e2.tar.gz linux-33940d09937276cd3c81f2874faf43e37c2db0e2.tar.bz2 linux-33940d09937276cd3c81f2874faf43e37c2db0e2.zip | |
target: encapsulate smp_mb__after_atomic()
The target code has a rather generous helping of smp_mb__after_atomic()
throughout the code base. Most atomic operations were followed by one
and none were preceded by smp_mb__before_atomic(), nor accompanied by a
comment explaining the need for a barrier.
Instead of trying to prove for every case whether or not it is needed,
this patch introduces atomic_inc_mb() and atomic_dec_mb(), which
explicitly include the memory barriers before and after the atomic
operation. For now they are defined in a target header, although they
could be of general use.
Most of the existing atomic/mb combinations were replaced by the new
helpers. In a few cases the atomic was sandwiched in
spin_lock/spin_unlock and I simply removed the barrier.
I suspect that in most cases the correct conversion would have been to
drop the barrier. I also suspect that a few cases exist where a) the
barrier was necessary and b) a second barrier before the atomic would
have been necessary and got added by this patch.
Signed-off-by: Joern Engel <joern@logfs.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'include/target')
| -rw-r--r-- | include/target/target_core_base.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index 9ec9864ecf38..b106240d8385 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -903,4 +903,18 @@ struct se_wwn { struct config_group fabric_stat_group; }; +static inline void atomic_inc_mb(atomic_t *v) +{ + smp_mb__before_atomic(); + atomic_inc(v); + smp_mb__after_atomic(); +} + +static inline void atomic_dec_mb(atomic_t *v) +{ + smp_mb__before_atomic(); + atomic_dec(v); + smp_mb__after_atomic(); +} + #endif /* TARGET_CORE_BASE_H */ |