From 3ccd6e83df8a0d4a664edeecc453c4fa046395fb Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Sun, 13 Sep 2015 02:30:46 -0700 Subject: [PATCH] target: Fix PR registration + APTPL RCU conversion regression This patch fixes a v4.2+ regression introduced by commit 79dc9c9e86 where lookup of t10_pr_registration->pr_reg_deve and associated ->pr_kref get was missing from __core_scsi3_do_alloc_registration(), which is responsible for setting DEF_PR_REG_ACTIVE. This would result in REGISTER operations completing successfully, but subsequent core_scsi3_pr_seq_non_holder() checking would fail with !DEF_PR_REG_ACTIVE -> RESERVATION CONFLICT status. Update __core_scsi3_add_registration() to drop ->pr_kref reference after registration and any optional ALL_TG_PT=1 processing has completed. Update core_scsi3_decode_spec_i_port() to release the new parent local_pr_reg->pr_kref as well. Also, update __core_scsi3_check_aptpl_registration() to perform the same target_nacl_find_deve() lookup + ->pr_kref get, now that __core_scsi3_add_registration() expects to drop the reference. Finally, since there are cases when se_dev_entry->se_lun_acl can still be dereferenced in core_scsi3_lunacl_undepend_item() while holding ->pr_kref, go ahead and move explicit rcu_assign_pointer() NULL assignments within core_disable_device_list_for_node() until after orig->pr_comp finishes. Reported-by: Scott L. Lykens Tested-by: Scott L. Lykens Cc: Christoph Hellwig Cc: Hannes Reinecke Cc: Lee Duncan Cc: # v4.2+ Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_device.c | 5 +- drivers/target/target_core_pr.c | 91 +++++++++++++++++++++-------- 2 files changed, 70 insertions(+), 26 deletions(-) diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index dcc424ac35d4..abf20763b0b6 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -427,8 +427,6 @@ void core_disable_device_list_for_node( 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; orig->creation_time = 0; orig->attach_count--; @@ -439,6 +437,9 @@ void core_disable_device_list_for_node( kref_put(&orig->pr_kref, target_pr_kref_release); wait_for_completion(&orig->pr_comp); + rcu_assign_pointer(orig->se_lun, NULL); + rcu_assign_pointer(orig->se_lun_acl, NULL); + kfree_rcu(orig, rcu_head); core_scsi3_free_pr_reg_from_nacl(dev, nacl); diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c index 5ab7100de17e..e7933115087a 100644 --- a/drivers/target/target_core_pr.c +++ b/drivers/target/target_core_pr.c @@ -618,7 +618,7 @@ static struct t10_pr_registration *__core_scsi3_do_alloc_registration( struct se_device *dev, struct se_node_acl *nacl, struct se_lun *lun, - struct se_dev_entry *deve, + struct se_dev_entry *dest_deve, u64 mapped_lun, unsigned char *isid, u64 sa_res_key, @@ -640,7 +640,29 @@ static struct t10_pr_registration *__core_scsi3_do_alloc_registration( INIT_LIST_HEAD(&pr_reg->pr_reg_atp_mem_list); atomic_set(&pr_reg->pr_res_holders, 0); pr_reg->pr_reg_nacl = nacl; - pr_reg->pr_reg_deve = deve; + /* + * For destination registrations for ALL_TG_PT=1 and SPEC_I_PT=1, + * the se_dev_entry->pr_ref will have been already obtained by + * core_get_se_deve_from_rtpi() or __core_scsi3_alloc_registration(). + * + * Otherwise, locate se_dev_entry now and obtain a reference until + * registration completes in __core_scsi3_add_registration(). + */ + if (dest_deve) { + pr_reg->pr_reg_deve = dest_deve; + } else { + rcu_read_lock(); + pr_reg->pr_reg_deve = target_nacl_find_deve(nacl, mapped_lun); + if (!pr_reg->pr_reg_deve) { + rcu_read_unlock(); + pr_err("Unable to locate PR deve %s mapped_lun: %llu\n", + nacl->initiatorname, mapped_lun); + kmem_cache_free(t10_pr_reg_cache, pr_reg); + return NULL; + } + kref_get(&pr_reg->pr_reg_deve->pr_kref); + rcu_read_unlock(); + } pr_reg->pr_res_mapped_lun = mapped_lun; pr_reg->pr_aptpl_target_lun = lun->unpacked_lun; pr_reg->tg_pt_sep_rtpi = lun->lun_rtpi; @@ -936,17 +958,29 @@ static int __core_scsi3_check_aptpl_registration( !(strcmp(pr_reg->pr_tport, t_port)) && (pr_reg->pr_reg_tpgt == tpgt) && (pr_reg->pr_aptpl_target_lun == target_lun)) { + /* + * Obtain the ->pr_reg_deve pointer + reference, that + * is released by __core_scsi3_add_registration() below. + */ + rcu_read_lock(); + pr_reg->pr_reg_deve = target_nacl_find_deve(nacl, mapped_lun); + if (!pr_reg->pr_reg_deve) { + pr_err("Unable to locate PR APTPL %s mapped_lun:" + " %llu\n", nacl->initiatorname, mapped_lun); + rcu_read_unlock(); + continue; + } + kref_get(&pr_reg->pr_reg_deve->pr_kref); + rcu_read_unlock(); pr_reg->pr_reg_nacl = nacl; pr_reg->tg_pt_sep_rtpi = lun->lun_rtpi; - list_del(&pr_reg->pr_reg_aptpl_list); spin_unlock(&pr_tmpl->aptpl_reg_lock); /* * At this point all of the pointers in *pr_reg will * be setup, so go ahead and add the registration. */ - __core_scsi3_add_registration(dev, nacl, pr_reg, 0, 0); /* * If this registration is the reservation holder, @@ -1044,18 +1078,11 @@ static void __core_scsi3_add_registration( __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. */ if (!pr_reg->pr_reg_all_tg_pt || register_move) - return; + goto out; /* * Walk pr_reg->pr_reg_atp_list and add registrations for ALL_TG_PT=1 * allocated in __core_scsi3_alloc_registration() @@ -1075,19 +1102,31 @@ static void __core_scsi3_add_registration( __core_scsi3_dump_registration(tfo, dev, nacl_tmp, pr_reg_tmp, register_type); spin_unlock(&pr_tmpl->registration_lock); - + /* + * Drop configfs group dependency reference and deve->pr_kref + * obtained from __core_scsi3_alloc_registration() code. + */ rcu_read_lock(); deve = pr_reg_tmp->pr_reg_deve; - if (deve) + if (deve) { set_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags); + core_scsi3_lunacl_undepend_item(deve); + pr_reg_tmp->pr_reg_deve = NULL; + } rcu_read_unlock(); - - /* - * Drop configfs group dependency reference from - * __core_scsi3_alloc_registration() - */ - core_scsi3_lunacl_undepend_item(pr_reg_tmp->pr_reg_deve); } +out: + /* + * Drop deve->pr_kref obtained in __core_scsi3_do_alloc_registration() + */ + rcu_read_lock(); + deve = pr_reg->pr_reg_deve; + if (deve) { + set_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags); + kref_put(&deve->pr_kref, target_pr_kref_release); + pr_reg->pr_reg_deve = NULL; + } + rcu_read_unlock(); } static int core_scsi3_alloc_registration( @@ -1785,9 +1824,11 @@ core_scsi3_decode_spec_i_port( dest_node_acl->initiatorname, i_buf, (dest_se_deve) ? dest_se_deve->mapped_lun : 0); - if (!dest_se_deve) + if (!dest_se_deve) { + kref_put(&local_pr_reg->pr_reg_deve->pr_kref, + target_pr_kref_release); continue; - + } core_scsi3_lunacl_undepend_item(dest_se_deve); core_scsi3_nodeacl_undepend_item(dest_node_acl); core_scsi3_tpg_undepend_item(dest_tpg); @@ -1823,9 +1864,11 @@ out: kmem_cache_free(t10_pr_reg_cache, dest_pr_reg); - if (!dest_se_deve) + if (!dest_se_deve) { + kref_put(&local_pr_reg->pr_reg_deve->pr_kref, + target_pr_kref_release); continue; - + } core_scsi3_lunacl_undepend_item(dest_se_deve); core_scsi3_nodeacl_undepend_item(dest_node_acl); core_scsi3_tpg_undepend_item(dest_tpg); -- 2.20.1