diff options
| 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 /drivers/target/target_core_device.c | |
| parent | target: remove some smp_mb__after_atomic()s (diff) | |
| download | linux-dev-33940d09937276cd3c81f2874faf43e37c2db0e2.tar.xz linux-dev-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 'drivers/target/target_core_device.c')
| -rw-r--r-- | drivers/target/target_core_device.c | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index e784284cbc2e..f5057a2f4ed1 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -224,8 +224,7 @@ struct se_dev_entry *core_get_se_deve_from_rtpi( if (port->sep_rtpi != rtpi) continue; - atomic_inc(&deve->pr_ref_count); - smp_mb__after_atomic(); + atomic_inc_mb(&deve->pr_ref_count); spin_unlock_irq(&nacl->device_list_lock); return deve; @@ -1388,8 +1387,7 @@ int core_dev_add_initiator_node_lun_acl( spin_lock(&lun->lun_acl_lock); list_add_tail(&lacl->lacl_list, &lun->lun_acl_list); - atomic_inc(&lun->lun_acl_count); - smp_mb__after_atomic(); + atomic_inc_mb(&lun->lun_acl_count); spin_unlock(&lun->lun_acl_lock); pr_debug("%s_TPG[%hu]_LUN[%u->%u] - Added %s ACL for " @@ -1422,8 +1420,7 @@ int core_dev_del_initiator_node_lun_acl( spin_lock(&lun->lun_acl_lock); list_del(&lacl->lacl_list); - atomic_dec(&lun->lun_acl_count); - smp_mb__after_atomic(); + atomic_dec_mb(&lun->lun_acl_count); spin_unlock(&lun->lun_acl_lock); core_disable_device_list_for_node(lun, NULL, lacl->mapped_lun, |