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Date: Sat, 17 Oct 2015 18:55:32 -0700
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, "Scott L. Lykens" <scott@...ens.org>,
Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
Lee Duncan <lduncan@...e.com>,
Nicholas Bellinger <nab@...ux-iscsi.org>
Subject: [PATCH 4.2 019/258] target: Fix PR registration + APTPL RCU conversion regression
4.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Nicholas Bellinger <nab@...ux-iscsi.org>
commit 3ccd6e83df8a0d4a664edeecc453c4fa046395fb upstream.
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 <scott@...ens.org>
Tested-by: Scott L. Lykens <scott@...ens.org>
Cc: Christoph Hellwig <hch@....de>
Cc: Hannes Reinecke <hare@...e.de>
Cc: Lee Duncan <lduncan@...e.com>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
drivers/target/target_core_device.c | 5 +
drivers/target/target_core_pr.c | 91 ++++++++++++++++++++++++++----------
2 files changed, 70 insertions(+), 26 deletions(-)
--- 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);
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -618,7 +618,7 @@ static struct t10_pr_registration *__cor
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 *__cor
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_regi
!(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_registratio
__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_registratio
__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);
--
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