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_pr.c | |
parent | 74ed7e62289dc6d388996d7c8f89c2e7e95b9657 (diff) | |
download | op-kernel-dev-33940d09937276cd3c81f2874faf43e37c2db0e2.zip op-kernel-dev-33940d09937276cd3c81f2874faf43e37c2db0e2.tar.gz |
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_pr.c')
-rw-r--r-- | drivers/target/target_core_pr.c | 90 |
1 files changed, 30 insertions, 60 deletions
diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c index 281d52e..48a8010 100644 --- a/drivers/target/target_core_pr.c +++ b/drivers/target/target_core_pr.c @@ -674,8 +674,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration( */ spin_lock(&dev->se_port_lock); list_for_each_entry_safe(port, port_tmp, &dev->dev_sep_list, sep_list) { - atomic_inc(&port->sep_tg_pt_ref_cnt); - smp_mb__after_atomic(); + atomic_inc_mb(&port->sep_tg_pt_ref_cnt); spin_unlock(&dev->se_port_lock); spin_lock_bh(&port->sep_alua_lock); @@ -709,8 +708,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration( if (strcmp(nacl->initiatorname, nacl_tmp->initiatorname)) continue; - atomic_inc(&deve_tmp->pr_ref_count); - smp_mb__after_atomic(); + atomic_inc_mb(&deve_tmp->pr_ref_count); spin_unlock_bh(&port->sep_alua_lock); /* * Grab a configfs group dependency that is released @@ -722,10 +720,8 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration( if (ret < 0) { pr_err("core_scsi3_lunacl_depend" "_item() failed\n"); - atomic_dec(&port->sep_tg_pt_ref_cnt); - smp_mb__after_atomic(); - atomic_dec(&deve_tmp->pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&port->sep_tg_pt_ref_cnt); + atomic_dec_mb(&deve_tmp->pr_ref_count); goto out; } /* @@ -739,10 +735,8 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration( nacl_tmp, deve_tmp, NULL, sa_res_key, all_tg_pt, aptpl); if (!pr_reg_atp) { - atomic_dec(&port->sep_tg_pt_ref_cnt); - smp_mb__after_atomic(); - atomic_dec(&deve_tmp->pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&port->sep_tg_pt_ref_cnt); + atomic_dec_mb(&deve_tmp->pr_ref_count); core_scsi3_lunacl_undepend_item(deve_tmp); goto out; } @@ -754,8 +748,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration( spin_unlock_bh(&port->sep_alua_lock); spin_lock(&dev->se_port_lock); - atomic_dec(&port->sep_tg_pt_ref_cnt); - smp_mb__after_atomic(); + atomic_dec_mb(&port->sep_tg_pt_ref_cnt); } spin_unlock(&dev->se_port_lock); @@ -1109,8 +1102,7 @@ static struct t10_pr_registration *__core_scsi3_locate_pr_reg( if (dev->dev_attrib.enforce_pr_isids) continue; } - atomic_inc(&pr_reg->pr_res_holders); - smp_mb__after_atomic(); + atomic_inc_mb(&pr_reg->pr_res_holders); spin_unlock(&pr_tmpl->registration_lock); return pr_reg; } @@ -1124,8 +1116,7 @@ static struct t10_pr_registration *__core_scsi3_locate_pr_reg( if (strcmp(isid, pr_reg->pr_reg_isid)) continue; - atomic_inc(&pr_reg->pr_res_holders); - smp_mb__after_atomic(); + atomic_inc_mb(&pr_reg->pr_res_holders); spin_unlock(&pr_tmpl->registration_lock); return pr_reg; } @@ -1154,8 +1145,7 @@ static struct t10_pr_registration *core_scsi3_locate_pr_reg( static void core_scsi3_put_pr_reg(struct t10_pr_registration *pr_reg) { - atomic_dec(&pr_reg->pr_res_holders); - smp_mb__after_atomic(); + atomic_dec_mb(&pr_reg->pr_res_holders); } static int core_scsi3_check_implicit_release( @@ -1348,8 +1338,7 @@ static void core_scsi3_tpg_undepend_item(struct se_portal_group *tpg) configfs_undepend_item(tpg->se_tpg_tfo->tf_subsys, &tpg->tpg_group.cg_item); - atomic_dec(&tpg->tpg_pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&tpg->tpg_pr_ref_count); } static int core_scsi3_nodeacl_depend_item(struct se_node_acl *nacl) @@ -1368,16 +1357,14 @@ static void core_scsi3_nodeacl_undepend_item(struct se_node_acl *nacl) struct se_portal_group *tpg = nacl->se_tpg; if (nacl->dynamic_node_acl) { - atomic_dec(&nacl->acl_pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&nacl->acl_pr_ref_count); return; } configfs_undepend_item(tpg->se_tpg_tfo->tf_subsys, &nacl->acl_group.cg_item); - atomic_dec(&nacl->acl_pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&nacl->acl_pr_ref_count); } static int core_scsi3_lunacl_depend_item(struct se_dev_entry *se_deve) @@ -1407,8 +1394,7 @@ static void core_scsi3_lunacl_undepend_item(struct se_dev_entry *se_deve) * For nacl->dynamic_node_acl=1 */ if (!lun_acl) { - atomic_dec(&se_deve->pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&se_deve->pr_ref_count); return; } nacl = lun_acl->se_lun_nacl; @@ -1417,8 +1403,7 @@ static void core_scsi3_lunacl_undepend_item(struct se_dev_entry *se_deve) configfs_undepend_item(tpg->se_tpg_tfo->tf_subsys, &lun_acl->se_lun_group.cg_item); - atomic_dec(&se_deve->pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&se_deve->pr_ref_count); } static sense_reason_t @@ -1551,15 +1536,13 @@ core_scsi3_decode_spec_i_port( if (!i_str) continue; - atomic_inc(&tmp_tpg->tpg_pr_ref_count); - smp_mb__after_atomic(); + atomic_inc_mb(&tmp_tpg->tpg_pr_ref_count); spin_unlock(&dev->se_port_lock); if (core_scsi3_tpg_depend_item(tmp_tpg)) { pr_err(" core_scsi3_tpg_depend_item()" " for tmp_tpg\n"); - atomic_dec(&tmp_tpg->tpg_pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&tmp_tpg->tpg_pr_ref_count); ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; goto out_unmap; } @@ -1571,10 +1554,8 @@ core_scsi3_decode_spec_i_port( spin_lock_irq(&tmp_tpg->acl_node_lock); dest_node_acl = __core_tpg_get_initiator_node_acl( tmp_tpg, i_str); - if (dest_node_acl) { - atomic_inc(&dest_node_acl->acl_pr_ref_count); - smp_mb__after_atomic(); - } + if (dest_node_acl) + atomic_inc_mb(&dest_node_acl->acl_pr_ref_count); spin_unlock_irq(&tmp_tpg->acl_node_lock); if (!dest_node_acl) { @@ -1586,8 +1567,7 @@ core_scsi3_decode_spec_i_port( if (core_scsi3_nodeacl_depend_item(dest_node_acl)) { pr_err("configfs_depend_item() failed" " for dest_node_acl->acl_group\n"); - atomic_dec(&dest_node_acl->acl_pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&dest_node_acl->acl_pr_ref_count); core_scsi3_tpg_undepend_item(tmp_tpg); ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; goto out_unmap; @@ -1646,8 +1626,7 @@ core_scsi3_decode_spec_i_port( if (core_scsi3_lunacl_depend_item(dest_se_deve)) { pr_err("core_scsi3_lunacl_depend_item()" " failed\n"); - atomic_dec(&dest_se_deve->pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&dest_se_deve->pr_ref_count); core_scsi3_nodeacl_undepend_item(dest_node_acl); core_scsi3_tpg_undepend_item(dest_tpg); ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; @@ -3167,15 +3146,13 @@ core_scsi3_emulate_pro_register_and_move(struct se_cmd *cmd, u64 res_key, if (!dest_tf_ops) continue; - atomic_inc(&dest_se_tpg->tpg_pr_ref_count); - smp_mb__after_atomic(); + atomic_inc_mb(&dest_se_tpg->tpg_pr_ref_count); spin_unlock(&dev->se_port_lock); if (core_scsi3_tpg_depend_item(dest_se_tpg)) { pr_err("core_scsi3_tpg_depend_item() failed" " for dest_se_tpg\n"); - atomic_dec(&dest_se_tpg->tpg_pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&dest_se_tpg->tpg_pr_ref_count); ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; goto out_put_pr_reg; } @@ -3271,10 +3248,8 @@ after_iport_check: spin_lock_irq(&dest_se_tpg->acl_node_lock); dest_node_acl = __core_tpg_get_initiator_node_acl(dest_se_tpg, initiator_str); - if (dest_node_acl) { - atomic_inc(&dest_node_acl->acl_pr_ref_count); - smp_mb__after_atomic(); - } + if (dest_node_acl) + atomic_inc_mb(&dest_node_acl->acl_pr_ref_count); spin_unlock_irq(&dest_se_tpg->acl_node_lock); if (!dest_node_acl) { @@ -3288,8 +3263,7 @@ after_iport_check: if (core_scsi3_nodeacl_depend_item(dest_node_acl)) { pr_err("core_scsi3_nodeacl_depend_item() for" " dest_node_acl\n"); - atomic_dec(&dest_node_acl->acl_pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&dest_node_acl->acl_pr_ref_count); dest_node_acl = NULL; ret = TCM_INVALID_PARAMETER_LIST; goto out; @@ -3313,8 +3287,7 @@ after_iport_check: if (core_scsi3_lunacl_depend_item(dest_se_deve)) { pr_err("core_scsi3_lunacl_depend_item() failed\n"); - atomic_dec(&dest_se_deve->pr_ref_count); - smp_mb__after_atomic(); + atomic_dec_mb(&dest_se_deve->pr_ref_count); dest_se_deve = NULL; ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; goto out; @@ -3879,8 +3852,7 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd) se_tpg = pr_reg->pr_reg_nacl->se_tpg; add_desc_len = 0; - atomic_inc(&pr_reg->pr_res_holders); - smp_mb__after_atomic(); + atomic_inc_mb(&pr_reg->pr_res_holders); spin_unlock(&pr_tmpl->registration_lock); /* * Determine expected length of $FABRIC_MOD specific @@ -3893,8 +3865,7 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd) pr_warn("SPC-3 PRIN READ_FULL_STATUS ran" " out of buffer: %d\n", cmd->data_length); spin_lock(&pr_tmpl->registration_lock); - atomic_dec(&pr_reg->pr_res_holders); - smp_mb__after_atomic(); + atomic_dec_mb(&pr_reg->pr_res_holders); break; } /* @@ -3955,8 +3926,7 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd) se_nacl, pr_reg, &format_code, &buf[off+4]); spin_lock(&pr_tmpl->registration_lock); - atomic_dec(&pr_reg->pr_res_holders); - smp_mb__after_atomic(); + atomic_dec_mb(&pr_reg->pr_res_holders); /* * Set the ADDITIONAL DESCRIPTOR LENGTH */ |