From 80bfdfa92481d431b199eff72788588d13a3988f Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Wed, 25 Mar 2015 01:02:57 -0700 Subject: [PATCH] target/pr: Use atomic bitop for se_dev_entry->deve_flags reservation check This patch converts the core_scsi3_pr_seq_non_holder() check for non reservation holding registrations to use an atomic bitop in ->deve_flags to determine if a registration is currently active. It also includes associated a set_bit() in __core_scsi3_add_registration() and clear_bit() in __core_scsi3_free_registration(), if se_dev_entry still exists, and has not already been released via se_dev_entry shutdown path in core_disable_device_list_for_node(). Also, clear_bit in core_disable_device_list_for_node as well to ensure the read-critical path in core_scsi3_pr_seq_non_holder() picks up the new state, preceeding the final kfree_rcu() call. Reported-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Cc: Sagi Grimberg Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_device.c | 1 + drivers/target/target_core_pr.c | 58 +++++++++++++++++++---------- include/target/target_core_base.h | 3 +- 3 files changed, 42 insertions(+), 20 deletions(-) diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index e44e6bd66659..97792cc81fe4 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -413,6 +413,7 @@ void core_disable_device_list_for_node( core_scsi3_ua_release_all(orig); hlist_del_rcu(&orig->link); + clear_bit(DEF_PR_REG_ACTIVE, &orig->deve_flags); rcu_assign_pointer(orig->se_lun, NULL); rcu_assign_pointer(orig->se_lun_acl, NULL); orig->lun_flags = 0; diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c index 909573a682d5..66e686bdf894 100644 --- a/drivers/target/target_core_pr.c +++ b/drivers/target/target_core_pr.c @@ -327,9 +327,13 @@ static int core_scsi3_pr_seq_non_holder( int we = 0; /* Write Exclusive */ int legacy = 0; /* Act like a legacy device and return * RESERVATION CONFLICT on some CDBs */ + bool registered = false; rcu_read_lock(); se_deve = target_nacl_find_deve(nacl, cmd->orig_fe_lun); + if (se_deve) + registered = test_bit(DEF_PR_REG_ACTIVE, &se_deve->deve_flags); + rcu_read_unlock(); /* * Determine if the registration should be ignored due to * non-matching ISIDs in target_scsi3_pr_reservation_check(). @@ -346,7 +350,7 @@ static int core_scsi3_pr_seq_non_holder( * Some commands are only allowed for the persistent reservation * holder. */ - if ((se_deve->def_pr_registered) && !(ignore_reg)) + if ((registered) && !(ignore_reg)) registered_nexus = 1; break; case PR_TYPE_WRITE_EXCLUSIVE_REGONLY: @@ -356,7 +360,7 @@ static int core_scsi3_pr_seq_non_holder( * Some commands are only allowed for registered I_T Nexuses. */ reg_only = 1; - if ((se_deve->def_pr_registered) && !(ignore_reg)) + if ((registered) && !(ignore_reg)) registered_nexus = 1; break; case PR_TYPE_WRITE_EXCLUSIVE_ALLREG: @@ -366,14 +370,12 @@ static int core_scsi3_pr_seq_non_holder( * Each registered I_T Nexus is a reservation holder. */ all_reg = 1; - if ((se_deve->def_pr_registered) && !(ignore_reg)) + if ((registered) && !(ignore_reg)) registered_nexus = 1; break; default: - rcu_read_unlock(); return -EINVAL; } - rcu_read_unlock(); /* * Referenced from spc4r17 table 45 for *NON* PR holder access */ @@ -1009,10 +1011,6 @@ static void __core_scsi3_dump_registration( pr_reg->pr_reg_aptpl); } -/* - * this function can be called with struct se_device->dev_reservation_lock - * when register_move = 1 - */ static void __core_scsi3_add_registration( struct se_device *dev, struct se_node_acl *nacl, @@ -1023,6 +1021,7 @@ static void __core_scsi3_add_registration( const struct target_core_fabric_ops *tfo = nacl->se_tpg->se_tpg_tfo; struct t10_pr_registration *pr_reg_tmp, *pr_reg_tmp_safe; struct t10_reservation *pr_tmpl = &dev->t10_pr; + struct se_dev_entry *deve; /* * Increment PRgeneration counter for struct se_device upon a successful @@ -1039,10 +1038,16 @@ static void __core_scsi3_add_registration( spin_lock(&pr_tmpl->registration_lock); list_add_tail(&pr_reg->pr_reg_list, &pr_tmpl->registration_list); - pr_reg->pr_reg_deve->def_pr_registered = 1; __core_scsi3_dump_registration(tfo, dev, nacl, pr_reg, register_type); spin_unlock(&pr_tmpl->registration_lock); + + rcu_read_lock(); + deve = pr_reg->pr_reg_deve; + if (deve) + set_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags); + rcu_read_unlock(); + /* * Skip extra processing for ALL_TG_PT=0 or REGISTER_AND_MOVE. */ @@ -1054,6 +1059,8 @@ static void __core_scsi3_add_registration( */ list_for_each_entry_safe(pr_reg_tmp, pr_reg_tmp_safe, &pr_reg->pr_reg_atp_list, pr_reg_atp_mem_list) { + struct se_node_acl *nacl_tmp = pr_reg_tmp->pr_reg_nacl; + list_del(&pr_reg_tmp->pr_reg_atp_mem_list); pr_reg_tmp->pr_res_generation = core_scsi3_pr_generation(dev); @@ -1061,12 +1068,17 @@ static void __core_scsi3_add_registration( spin_lock(&pr_tmpl->registration_lock); list_add_tail(&pr_reg_tmp->pr_reg_list, &pr_tmpl->registration_list); - pr_reg_tmp->pr_reg_deve->def_pr_registered = 1; - __core_scsi3_dump_registration(tfo, dev, - pr_reg_tmp->pr_reg_nacl, pr_reg_tmp, - register_type); + __core_scsi3_dump_registration(tfo, dev, nacl_tmp, pr_reg_tmp, + register_type); spin_unlock(&pr_tmpl->registration_lock); + + rcu_read_lock(); + deve = pr_reg_tmp->pr_reg_deve; + if (deve) + set_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags); + rcu_read_unlock(); + /* * Drop configfs group dependency reference from * __core_scsi3_alloc_registration() @@ -1242,13 +1254,13 @@ static void __core_scsi3_free_registration( const struct target_core_fabric_ops *tfo = pr_reg->pr_reg_nacl->se_tpg->se_tpg_tfo; struct t10_reservation *pr_tmpl = &dev->t10_pr; + struct se_node_acl *nacl = pr_reg->pr_reg_nacl; + struct se_dev_entry *deve; char i_buf[PR_REG_ISID_ID_LEN]; memset(i_buf, 0, PR_REG_ISID_ID_LEN); core_pr_dump_initiator_port(pr_reg, i_buf, PR_REG_ISID_ID_LEN); - pr_reg->pr_reg_deve->def_pr_registered = 0; - pr_reg->pr_reg_deve->pr_res_key = 0; if (!list_empty(&pr_reg->pr_reg_list)) list_del(&pr_reg->pr_reg_list); /* @@ -1257,6 +1269,8 @@ static void __core_scsi3_free_registration( */ if (dec_holders) core_scsi3_put_pr_reg(pr_reg); + + spin_unlock(&pr_tmpl->registration_lock); /* * Wait until all reference from any other I_T nexuses for this * *pr_reg have been released. Because list_del() is called above, @@ -1264,13 +1278,18 @@ static void __core_scsi3_free_registration( * count back to zero, and we release *pr_reg. */ while (atomic_read(&pr_reg->pr_res_holders) != 0) { - spin_unlock(&pr_tmpl->registration_lock); pr_debug("SPC-3 PR [%s] waiting for pr_res_holders\n", tfo->get_fabric_name()); cpu_relax(); - spin_lock(&pr_tmpl->registration_lock); } + rcu_read_lock(); + deve = target_nacl_find_deve(nacl, pr_reg->pr_res_mapped_lun); + if (deve) + clear_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags); + rcu_read_unlock(); + + spin_lock(&pr_tmpl->registration_lock); pr_debug("SPC-3 PR [%s] Service Action: UNREGISTER Initiator" " Node: %s%s\n", tfo->get_fabric_name(), pr_reg->pr_reg_nacl->initiatorname, @@ -3421,13 +3440,14 @@ after_iport_check: dest_pr_reg = __core_scsi3_locate_pr_reg(dev, dest_node_acl, iport_ptr); if (!dest_pr_reg) { + spin_unlock(&dev->dev_reservation_lock); if (core_scsi3_alloc_registration(cmd->se_dev, dest_node_acl, dest_se_deve, iport_ptr, sa_res_key, 0, aptpl, 2, 1)) { - spin_unlock(&dev->dev_reservation_lock); ret = TCM_INVALID_PARAMETER_LIST; goto out; } + spin_lock(&dev->dev_reservation_lock); dest_pr_reg = __core_scsi3_locate_pr_reg(dev, dest_node_acl, iport_ptr); new_reg = 1; diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index b518523cba7b..508528a5e927 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -638,7 +638,6 @@ struct se_lun_acl { }; struct se_dev_entry { - bool def_pr_registered; /* See transport_lunflags_table */ u32 lun_flags; u32 mapped_lun; @@ -655,6 +654,8 @@ struct se_dev_entry { struct se_lun_acl __rcu *se_lun_acl; spinlock_t ua_lock; struct se_lun __rcu *se_lun; +#define DEF_PR_REG_ACTIVE 1 + unsigned long deve_flags; struct list_head alua_port_list; struct list_head ua_list; struct hlist_node link; -- 2.30.2