Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932428AbbELJgM (ORCPT ); Tue, 12 May 2015 05:36:12 -0400 Received: from mail-oi0-f45.google.com ([209.85.218.45]:34559 "EHLO mail-oi0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932390AbbELJ2F (ORCPT ); Tue, 12 May 2015 05:28:05 -0400 From: "Nicholas A. Bellinger" To: target-devel Cc: linux-scsi , linux-kernel , Hannes Reinecke , Christoph Hellwig , Sagi Grimberg , Nicholas Bellinger Subject: [PATCH 05/12] target: Convert transport_lookup_*_lun to RCU reader Date: Tue, 12 May 2015 09:25:29 +0000 Message-Id: <1431422736-29125-6-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: 10117 Lines: 291 From: Nicholas Bellinger This patch converts transport_lookup_*_lun() fast-path code to use RCU read path primitives when looking up se_dev_entry. It adds a new array of pointers in se_node_acl->lun_entry_hlist for this purpose. For transport_lookup_cmd_lun() code, it works with existing per-cpu se_lun->lun_ref when associating se_cmd with se_lun + se_device. Also, go ahead and update core_create_device_list_for_node() + core_free_device_list_for_node() to use ->lun_entry_hlist. Finally, now that se_node_acl->lun_entry_hlist fast path access uses RCU protected pointers, go ahead and convert remaining non-fast path RCU updater code using ->lun_entry_lock to struct mutex. Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: Sagi Grimberg Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_device.c | 60 +++++++++++++++++++++++-------------- drivers/target/target_core_pr.c | 1 + drivers/target/target_core_tpg.c | 38 ++--------------------- include/target/target_core_base.h | 3 +- 4 files changed, 42 insertions(+), 60 deletions(-) diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index 1df14ce..36e7d13 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -59,17 +59,24 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun) { struct se_lun *se_lun = NULL; struct se_session *se_sess = se_cmd->se_sess; + struct se_node_acl *nacl = se_sess->se_node_acl; struct se_device *dev; - unsigned long flags; + struct se_dev_entry *deve; if (unpacked_lun >= TRANSPORT_MAX_LUNS_PER_TPG) return TCM_NON_EXISTENT_LUN; - spin_lock_irqsave(&se_sess->se_node_acl->device_list_lock, flags); - se_cmd->se_deve = se_sess->se_node_acl->device_list[unpacked_lun]; - if (se_cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_INITIATOR_ACCESS) { - struct se_dev_entry *deve = se_cmd->se_deve; - + rcu_read_lock(); + deve = target_nacl_find_deve(nacl, unpacked_lun); + if (deve && deve->lun_flags & TRANSPORT_LUNFLAGS_INITIATOR_ACCESS) { + /* + * Make sure that target_enable_device_list_for_node() + * has not already cleared the RCU protected pointers. + */ + if (!deve->se_lun) { + rcu_read_unlock(); + goto check_lun; + } deve->total_cmds++; if ((se_cmd->data_direction == DMA_TO_DEVICE) && @@ -78,7 +85,7 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun) " Access for 0x%08x\n", se_cmd->se_tfo->get_fabric_name(), unpacked_lun); - spin_unlock_irqrestore(&se_sess->se_node_acl->device_list_lock, flags); + rcu_read_unlock(); return TCM_WRITE_PROTECTED; } @@ -96,8 +103,9 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun) percpu_ref_get(&se_lun->lun_ref); se_cmd->lun_ref_active = true; } - spin_unlock_irqrestore(&se_sess->se_node_acl->device_list_lock, flags); + rcu_read_unlock(); +check_lun: if (!se_lun) { /* * Use the se_portal_group->tpg_virt_lun0 to allow for @@ -146,25 +154,33 @@ int transport_lookup_tmr_lun(struct se_cmd *se_cmd, u32 unpacked_lun) struct se_dev_entry *deve; struct se_lun *se_lun = NULL; struct se_session *se_sess = se_cmd->se_sess; + struct se_node_acl *nacl = se_sess->se_node_acl; struct se_tmr_req *se_tmr = se_cmd->se_tmr_req; unsigned long flags; if (unpacked_lun >= TRANSPORT_MAX_LUNS_PER_TPG) return -ENODEV; - spin_lock_irqsave(&se_sess->se_node_acl->device_list_lock, flags); - se_cmd->se_deve = se_sess->se_node_acl->device_list[unpacked_lun]; - deve = se_cmd->se_deve; - - if (deve->lun_flags & TRANSPORT_LUNFLAGS_INITIATOR_ACCESS) { + rcu_read_lock(); + deve = target_nacl_find_deve(nacl, unpacked_lun); + if (deve && deve->lun_flags & TRANSPORT_LUNFLAGS_INITIATOR_ACCESS) { + /* + * Make sure that target_enable_device_list_for_node() + * has not already cleared the RCU protected pointers. + */ + if (!deve->se_lun) { + rcu_read_unlock(); + goto check_lun; + } se_tmr->tmr_lun = deve->se_lun; se_cmd->se_lun = deve->se_lun; se_lun = deve->se_lun; se_cmd->pr_res_key = deve->pr_res_key; se_cmd->orig_fe_lun = unpacked_lun; } - spin_unlock_irqrestore(&se_sess->se_node_acl->device_list_lock, flags); + rcu_read_unlock(); +check_lun: if (!se_lun) { pr_debug("TARGET_CORE[%s]: Detected NON_EXISTENT_LUN" " Access for 0x%08x\n", @@ -269,7 +285,7 @@ void core_update_device_list_access( { struct se_dev_entry *deve; - spin_lock_irq(&nacl->lun_entry_lock); + mutex_lock(&nacl->lun_entry_mutex); deve = target_nacl_find_deve(nacl, mapped_lun); if (deve) { if (lun_access & TRANSPORT_LUNFLAGS_READ_WRITE) { @@ -280,7 +296,7 @@ void core_update_device_list_access( deve->lun_flags |= TRANSPORT_LUNFLAGS_READ_ONLY; } } - spin_unlock_irq(&nacl->lun_entry_lock); + mutex_unlock(&nacl->lun_entry_mutex); synchronize_rcu(); } @@ -345,7 +361,7 @@ int core_enable_device_list_for_node( new->creation_time = get_jiffies_64(); new->attach_count++; - spin_lock_irq(&nacl->device_list_lock); + mutex_lock(&nacl->lun_entry_mutex); orig = target_nacl_find_deve(nacl, mapped_lun); if (orig && orig->lun_flags & TRANSPORT_LUNFLAGS_INITIATOR_ACCESS) { BUG_ON(orig->se_lun_acl != NULL); @@ -354,7 +370,7 @@ int core_enable_device_list_for_node( rcu_assign_pointer(new->se_lun, lun); rcu_assign_pointer(new->se_lun_acl, lun_acl); hlist_add_head_rcu(&new->link, &nacl->lun_entry_hlist); - spin_unlock_irq(&nacl->device_list_lock); + mutex_unlock(&nacl->lun_entry_mutex); spin_lock_bh(&port->sep_alua_lock); list_del(&orig->alua_port_list); @@ -368,7 +384,7 @@ int core_enable_device_list_for_node( rcu_assign_pointer(new->se_lun, lun); rcu_assign_pointer(new->se_lun_acl, lun_acl); hlist_add_head_rcu(&new->link, &nacl->lun_entry_hlist); - spin_unlock_irq(&nacl->device_list_lock); + mutex_unlock(&nacl->lun_entry_mutex); spin_lock_bh(&port->sep_alua_lock); list_add_tail(&new->alua_port_list, &port->sep_alua_list); @@ -393,10 +409,10 @@ int core_disable_device_list_for_node( struct se_port *port = lun->lun_sep; struct se_dev_entry *orig; - spin_lock_irq(&nacl->device_list_lock); + mutex_lock(&nacl->lun_entry_mutex); orig = target_nacl_find_deve(nacl, mapped_lun); if (!orig) { - spin_unlock_irq(&nacl->device_list_lock); + mutex_unlock(&nacl->lun_entry_mutex); return 0; } /* @@ -432,7 +448,7 @@ int core_disable_device_list_for_node( orig->creation_time = 0; orig->attach_count--; hlist_del_rcu(&orig->link); - spin_unlock_irq(&nacl->device_list_lock); + mutex_unlock(&nacl->lun_entry_mutex); /* * Fire off RCU callback to wait for any in process SPEC_I_PT=1 diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c index 8052d40..721b664 100644 --- a/drivers/target/target_core_pr.c +++ b/drivers/target/target_core_pr.c @@ -1066,6 +1066,7 @@ static void __core_scsi3_add_registration( pr_reg_tmp->pr_reg_nacl, pr_reg_tmp, register_type); spin_unlock(&pr_tmpl->registration_lock); + /* * Drop configfs group dependency reference from * __core_scsi3_alloc_registration() diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c index dbdd3e3..f9487e5 100644 --- a/drivers/target/target_core_tpg.c +++ b/drivers/target/target_core_tpg.c @@ -222,35 +222,6 @@ static void *array_zalloc(int n, size_t size, gfp_t flags) return a; } -/* core_create_device_list_for_node(): - * - * - */ -static int core_create_device_list_for_node(struct se_node_acl *nacl) -{ - struct se_dev_entry *deve; - int i; - - nacl->device_list = array_zalloc(TRANSPORT_MAX_LUNS_PER_TPG, - sizeof(struct se_dev_entry), GFP_KERNEL); - if (!nacl->device_list) { - pr_err("Unable to allocate memory for" - " struct se_node_acl->device_list\n"); - return -ENOMEM; - } - for (i = 0; i < TRANSPORT_MAX_LUNS_PER_TPG; i++) { - deve = nacl->device_list[i]; - - atomic_set(&deve->ua_count, 0); - atomic_set(&deve->pr_ref_count, 0); - spin_lock_init(&deve->ua_lock); - INIT_LIST_HEAD(&deve->alua_port_list); - INIT_LIST_HEAD(&deve->ua_list); - } - - return 0; -} - static struct se_node_acl *target_alloc_node_acl(struct se_portal_group *tpg, const unsigned char *initiatorname) { @@ -266,9 +237,8 @@ static struct se_node_acl *target_alloc_node_acl(struct se_portal_group *tpg, INIT_HLIST_HEAD(&acl->lun_entry_hlist); kref_init(&acl->acl_kref); init_completion(&acl->acl_free_comp); - spin_lock_init(&acl->device_list_lock); spin_lock_init(&acl->nacl_sess_lock); - spin_lock_init(&acl->lun_entry_lock); + mutex_init(&acl->lun_entry_mutex); atomic_set(&acl->acl_pr_ref_count, 0); if (tpg->se_tpg_tfo->tpg_get_default_depth) acl->queue_depth = tpg->se_tpg_tfo->tpg_get_default_depth(tpg); @@ -280,15 +250,11 @@ static struct se_node_acl *target_alloc_node_acl(struct se_portal_group *tpg, tpg->se_tpg_tfo->set_default_node_attributes(acl); - if (core_create_device_list_for_node(acl) < 0) - goto out_free_acl; if (core_set_queue_depth_for_node(tpg, acl) < 0) - goto out_free_device_list; + goto out_free_acl; return acl; -out_free_device_list: - core_free_device_list_for_node(acl, tpg); out_free_acl: kfree(acl); return NULL; diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index 6fb38df..3057eff 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -588,8 +588,7 @@ struct se_node_acl { struct se_dev_entry **device_list; struct se_session *nacl_sess; struct se_portal_group *se_tpg; - spinlock_t device_list_lock; - spinlock_t lun_entry_lock; + struct mutex lun_entry_mutex; spinlock_t nacl_sess_lock; struct config_group acl_group; struct config_group acl_attrib_group; -- 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/