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Commit 80bfdfa9 authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

target/pr: Use atomic bitop for se_dev_entry->deve_flags reservation check 



This patch converts the core_scsi3_pr_seq_non_holder() check for non
reservation holding registrations to use an atomic bitop in ->deve_flags
to determine if a registration is currently active.

It also includes associated a set_bit() in __core_scsi3_add_registration()
and clear_bit() in __core_scsi3_free_registration(), if se_dev_entry still
exists, and has not already been released via se_dev_entry shutdown path
in core_disable_device_list_for_node().

Also, clear_bit in core_disable_device_list_for_node as well to ensure
the read-critical path in core_scsi3_pr_seq_non_holder() picks up the
new state, preceeding the final kfree_rcu() call.

Reported-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Cc: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 29a05dee

drivers/target/target_core_device.c

+1 −0
Original line number Diff line number Diff line
@@ -413,6 +413,7 @@ void core_disable_device_list_for_node( 
	core_scsi3_ua_release_all(orig);



	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;

drivers/target/target_core_pr.c

+39 −19
Original line number Diff line number Diff line
@@ -327,9 +327,13 @@ static int core_scsi3_pr_seq_non_holder( 
	int we = 0; /* Write Exclusive */

	int legacy = 0; /* Act like a legacy device and return

			 * RESERVATION CONFLICT on some CDBs */

	bool registered = false;



	rcu_read_lock();

	se_deve = target_nacl_find_deve(nacl, cmd->orig_fe_lun);

	if (se_deve)

		registered = test_bit(DEF_PR_REG_ACTIVE, &se_deve->deve_flags);

	rcu_read_unlock();

	/*

	 * Determine if the registration should be ignored due to

	 * non-matching ISIDs in target_scsi3_pr_reservation_check().
@@ -346,7 +350,7 @@ static int core_scsi3_pr_seq_non_holder( 
		 * Some commands are only allowed for the persistent reservation

		 * holder.

		 */

		if ((se_deve->def_pr_registered) && !(ignore_reg))

		if ((registered) && !(ignore_reg))

			registered_nexus = 1;

		break;

	case PR_TYPE_WRITE_EXCLUSIVE_REGONLY:
@@ -356,7 +360,7 @@ static int core_scsi3_pr_seq_non_holder( 
		 * Some commands are only allowed for registered I_T Nexuses.

		 */

		reg_only = 1;

		if ((se_deve->def_pr_registered) && !(ignore_reg))

		if ((registered) && !(ignore_reg))

			registered_nexus = 1;

		break;

	case PR_TYPE_WRITE_EXCLUSIVE_ALLREG:
@@ -366,14 +370,12 @@ static int core_scsi3_pr_seq_non_holder( 
		 * Each registered I_T Nexus is a reservation holder.

		 */

		all_reg = 1;

		if ((se_deve->def_pr_registered) && !(ignore_reg))

		if ((registered) && !(ignore_reg))

			registered_nexus = 1;

		break;

	default:

		rcu_read_unlock();

		return -EINVAL;

	}

	rcu_read_unlock();

	/*

	 * Referenced from spc4r17 table 45 for *NON* PR holder access

	 */
@@ -1009,10 +1011,6 @@ static void __core_scsi3_dump_registration( 
		pr_reg->pr_reg_aptpl);

}



/*

 * this function can be called with struct se_device->dev_reservation_lock

 * when register_move = 1

 */

static void __core_scsi3_add_registration(

	struct se_device *dev,

	struct se_node_acl *nacl,
@@ -1023,6 +1021,7 @@ static void __core_scsi3_add_registration( 
	const struct target_core_fabric_ops *tfo = nacl->se_tpg->se_tpg_tfo;

	struct t10_pr_registration *pr_reg_tmp, *pr_reg_tmp_safe;

	struct t10_reservation *pr_tmpl = &dev->t10_pr;

	struct se_dev_entry *deve;



	/*

	 * Increment PRgeneration counter for struct se_device upon a successful
@@ -1039,10 +1038,16 @@ static void __core_scsi3_add_registration( 


	spin_lock(&pr_tmpl->registration_lock);

	list_add_tail(&pr_reg->pr_reg_list, &pr_tmpl->registration_list);

	pr_reg->pr_reg_deve->def_pr_registered = 1;



	__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.

	 */
@@ -1054,6 +1059,8 @@ static void __core_scsi3_add_registration( 
	 */

	list_for_each_entry_safe(pr_reg_tmp, pr_reg_tmp_safe,

			&pr_reg->pr_reg_atp_list, pr_reg_atp_mem_list) {

		struct se_node_acl *nacl_tmp = pr_reg_tmp->pr_reg_nacl;



		list_del(&pr_reg_tmp->pr_reg_atp_mem_list);



		pr_reg_tmp->pr_res_generation = core_scsi3_pr_generation(dev);
@@ -1061,12 +1068,17 @@ static void __core_scsi3_add_registration( 
		spin_lock(&pr_tmpl->registration_lock);

		list_add_tail(&pr_reg_tmp->pr_reg_list,

			      &pr_tmpl->registration_list);

		pr_reg_tmp->pr_reg_deve->def_pr_registered = 1;



		__core_scsi3_dump_registration(tfo, dev,

				pr_reg_tmp->pr_reg_nacl, pr_reg_tmp,

		__core_scsi3_dump_registration(tfo, dev, nacl_tmp, pr_reg_tmp,

					       register_type);

		spin_unlock(&pr_tmpl->registration_lock);



		rcu_read_lock();

		deve = pr_reg_tmp->pr_reg_deve;

		if (deve)

			set_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags);

		rcu_read_unlock();



		/*

		 * Drop configfs group dependency reference from

		 * __core_scsi3_alloc_registration()
@@ -1242,13 +1254,13 @@ static void __core_scsi3_free_registration( 
	const struct target_core_fabric_ops *tfo =

			pr_reg->pr_reg_nacl->se_tpg->se_tpg_tfo;

	struct t10_reservation *pr_tmpl = &dev->t10_pr;

	struct se_node_acl *nacl = pr_reg->pr_reg_nacl;

	struct se_dev_entry *deve;

	char i_buf[PR_REG_ISID_ID_LEN];



	memset(i_buf, 0, PR_REG_ISID_ID_LEN);

	core_pr_dump_initiator_port(pr_reg, i_buf, PR_REG_ISID_ID_LEN);



	pr_reg->pr_reg_deve->def_pr_registered = 0;

	pr_reg->pr_reg_deve->pr_res_key = 0;

	if (!list_empty(&pr_reg->pr_reg_list))

		list_del(&pr_reg->pr_reg_list);

	/*
@@ -1257,6 +1269,8 @@ static void __core_scsi3_free_registration( 
	 */

	if (dec_holders)

		core_scsi3_put_pr_reg(pr_reg);



	spin_unlock(&pr_tmpl->registration_lock);

	/*

	 * Wait until all reference from any other I_T nexuses for this

	 * *pr_reg have been released.  Because list_del() is called above,
@@ -1264,13 +1278,18 @@ static void __core_scsi3_free_registration( 
	 * count back to zero, and we release *pr_reg.

	 */

	while (atomic_read(&pr_reg->pr_res_holders) != 0) {

		spin_unlock(&pr_tmpl->registration_lock);

		pr_debug("SPC-3 PR [%s] waiting for pr_res_holders\n",

				tfo->get_fabric_name());

		cpu_relax();

		spin_lock(&pr_tmpl->registration_lock);

	}



	rcu_read_lock();

	deve = target_nacl_find_deve(nacl, pr_reg->pr_res_mapped_lun);

	if (deve)

		clear_bit(DEF_PR_REG_ACTIVE, &deve->deve_flags);

	rcu_read_unlock();



	spin_lock(&pr_tmpl->registration_lock);

	pr_debug("SPC-3 PR [%s] Service Action: UNREGISTER Initiator"

		" Node: %s%s\n", tfo->get_fabric_name(),

		pr_reg->pr_reg_nacl->initiatorname,
@@ -3421,13 +3440,14 @@ core_scsi3_emulate_pro_register_and_move(struct se_cmd *cmd, u64 res_key, 
	dest_pr_reg = __core_scsi3_locate_pr_reg(dev, dest_node_acl,

					iport_ptr);

	if (!dest_pr_reg) {

		spin_unlock(&dev->dev_reservation_lock);

		if (core_scsi3_alloc_registration(cmd->se_dev,

				dest_node_acl, dest_se_deve, iport_ptr,

				sa_res_key, 0, aptpl, 2, 1)) {

			spin_unlock(&dev->dev_reservation_lock);

			ret = TCM_INVALID_PARAMETER_LIST;

			goto out;

		}

		spin_lock(&dev->dev_reservation_lock);

		dest_pr_reg = __core_scsi3_locate_pr_reg(dev, dest_node_acl,

						iport_ptr);

		new_reg = 1;

include/target/target_core_base.h

+2 −1
Original line number Diff line number Diff line
@@ -638,7 +638,6 @@ struct se_lun_acl { 
};



struct se_dev_entry {

	bool			def_pr_registered;

	/* See transport_lunflags_table */

	u32			lun_flags;

	u32			mapped_lun;
@@ -655,6 +654,8 @@ struct se_dev_entry { 
	struct se_lun_acl __rcu	*se_lun_acl;

	spinlock_t		ua_lock;

	struct se_lun __rcu	*se_lun;

#define DEF_PR_REG_ACTIVE		1

	unsigned long		deve_flags;

	struct list_head	alua_port_list;

	struct list_head	ua_list;

	struct hlist_node	link;