From 33940d09937276cd3c81f2874faf43e37c2db0e2 Mon Sep 17 00:00:00 2001 From: Joern Engel Date: Tue, 16 Sep 2014 16:23:12 -0400 Subject: 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 Signed-off-by: Nicholas Bellinger --- drivers/target/loopback/tcm_loop.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'drivers/target/loopback') diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c index 340de9d92b15..a7f6dc646045 100644 --- a/drivers/target/loopback/tcm_loop.c +++ b/drivers/target/loopback/tcm_loop.c @@ -960,8 +960,7 @@ static int tcm_loop_port_link( struct tcm_loop_tpg, tl_se_tpg); struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba; - atomic_inc(&tl_tpg->tl_tpg_port_count); - smp_mb__after_atomic(); + atomic_inc_mb(&tl_tpg->tl_tpg_port_count); /* * Add Linux/SCSI struct scsi_device by HCTL */ @@ -995,8 +994,7 @@ static void tcm_loop_port_unlink( scsi_remove_device(sd); scsi_device_put(sd); - atomic_dec(&tl_tpg->tl_tpg_port_count); - smp_mb__after_atomic(); + atomic_dec_mb(&tl_tpg->tl_tpg_port_count); pr_debug("TCM_Loop_ConfigFS: Port Unlink Successful\n"); } -- cgit v1.2.3