Skip to content

Commit

Permalink
target: Fix PR registration + APTPL RCU conversion regression
Browse files Browse the repository at this point in the history 
This patch fixes a v4.2+ regression introduced by commit 79dc9c9
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@lykens.org>
Tested-by: Scott L. Lykens <scott@lykens.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Lee Duncan <lduncan@suse.com>
Cc: <stable@vger.kernel.org> # v4.2+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
  • Loading branch information
Nicholas Bellinger committed Sep 25, 2015
1 parent 9fd6008 commit 3ccd6e8
Show file tree
Hide file tree
Showing 2 changed files with 70 additions and 26 deletions.
5 changes: 3 additions & 2 deletions drivers/target/target_core_device.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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--;
Expand All @@ -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);
Expand Down
91 changes: 67 additions & 24 deletions drivers/target/target_core_pr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand All @@ -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;
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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()
Expand All @@ -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(
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -1823,9 +1864,11 @@ core_scsi3_decode_spec_i_port(

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);
Expand Down

0 comments on commit 3ccd6e8

Please sign in to comment.