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Commit 3ccd6e83 authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

target: Fix PR registration + APTPL RCU conversion regression 



This patch fixes a v4.2+ regression introduced by commit 79dc9c9e
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: default avatarScott L. Lykens <scott@lykens.org>
Tested-by: default avatarScott 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: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 9fd60088

drivers/target/target_core_device.c

+3 −2
Original line number Diff line number Diff line
@@ -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);

drivers/target/target_core_pr.c

+67 −24
Original line number Diff line number Diff line
@@ -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();



	}

out:

	/*

		 * Drop configfs group dependency reference from

		 * __core_scsi3_alloc_registration()

	 * Drop deve->pr_kref obtained in __core_scsi3_do_alloc_registration()

	 */

		core_scsi3_lunacl_undepend_item(pr_reg_tmp->pr_reg_deve);

	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 @@ 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);