Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932812AbbELJdn (ORCPT ); Tue, 12 May 2015 05:33:43 -0400 Received: from mail-ob0-f174.google.com ([209.85.214.174]:34503 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932398AbbELJ2H (ORCPT ); Tue, 12 May 2015 05:28:07 -0400 From: "Nicholas A. Bellinger" To: target-devel Cc: linux-scsi , linux-kernel , Hannes Reinecke , Christoph Hellwig , Sagi Grimberg , Nicholas Bellinger Subject: [PATCH 07/12] target/pr: Convert registration check to RCU pointer Date: Tue, 12 May 2015 09:25:31 +0000 Message-Id: <1431422736-29125-8-git-send-email-nab@daterainc.com> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1431422736-29125-1-git-send-email-nab@daterainc.com> References: <1431422736-29125-1-git-send-email-nab@daterainc.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9182 Lines: 262 From: Nicholas Bellinger This patch converts core_scsi3_pr_seq_non_holder() check for non reservation holding registrations to use se_deve->pr_reg as an RCU protected pointer. It also includes associated rcu_assign_pointer() + synchronize_rcu() in __core_scsi3_add_registration() and __core_scsi3_free_registration() for the RCU updater path. Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: Sagi Grimberg Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_device.c | 1 + drivers/target/target_core_pr.c | 75 +++++++++++++++++++++++++++---------- include/target/target_core_base.h | 4 +- 3 files changed, 59 insertions(+), 21 deletions(-) diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index 911758b..430d3d6 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -448,6 +448,7 @@ int core_disable_device_list_for_node( * Disable struct se_dev_entry LUN ACL mapping */ core_scsi3_ua_release_all(orig); + rcu_assign_pointer(orig->pr_reg, NULL); 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 c0b593a..491043d 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 = (se_deve->pr_reg != NULL); + 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 +1038,22 @@ 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); + + mutex_lock(&nacl->lun_entry_mutex); + deve = target_nacl_find_deve(nacl, pr_reg->pr_res_mapped_lun); + if (deve) + rcu_assign_pointer(deve->pr_reg, pr_reg); + mutex_unlock(&nacl->lun_entry_mutex); + + /* + * Wait for read path critical RCU in core_scsi3_pr_seq_non_holder() + * conditional checks for deve->pr_reg pointer access complete. + */ + synchronize_rcu(); + /* * Skip extra processing for ALL_TG_PT=0 or REGISTER_AND_MOVE. */ @@ -1054,6 +1065,8 @@ 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); @@ -1061,13 +1074,23 @@ 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); + mutex_lock(&nacl->lun_entry_mutex); + deve = target_nacl_find_deve(nacl_tmp, pr_reg_tmp->pr_res_mapped_lun); + if (deve) + rcu_assign_pointer(deve->pr_reg, pr_reg_tmp); + mutex_unlock(&nacl->lun_entry_mutex); + + /* + * Wait for read path critical RCU in core_scsi3_pr_seq_non_holder() + * conditional checks for deve->pr_reg pointer access complete. + */ + synchronize_rcu(); + /* * Drop configfs group dependency reference from * __core_scsi3_alloc_registration() @@ -1243,13 +1266,13 @@ 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); /* @@ -1258,6 +1281,8 @@ 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, @@ -1265,13 +1290,24 @@ 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); } + mutex_lock(&nacl->lun_entry_mutex); + deve = target_nacl_find_deve(nacl, pr_reg->pr_res_mapped_lun); + if (deve) + rcu_assign_pointer(deve->pr_reg, NULL); + mutex_unlock(&nacl->lun_entry_mutex); + + /* + * Wait for read path critical RCU in core_scsi3_pr_seq_non_holder() + * conditional checks for deve->pr_reg pointer access complete. + */ + synchronize_rcu(); + + 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, @@ -3428,13 +3464,14 @@ 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 1b06d27..2f0c830 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -640,7 +640,6 @@ struct se_lun_acl { }; struct se_dev_entry { - bool def_pr_registered; /* See transport_lunflags_table */ u32 lun_flags; u32 mapped_lun; @@ -657,7 +656,8 @@ struct se_dev_entry { struct se_node_acl *se_node_acl; struct se_lun_acl __rcu *se_lun_acl; spinlock_t ua_lock; - struct se_lun *se_lun; + struct se_lun __rcu *se_lun; + struct t10_pr_registration __rcu *pr_reg; struct list_head alua_port_list; struct list_head ua_list; struct hlist_node link; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/