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Commit 9b31a328 authored by Nicholas Bellinger's avatar Nicholas Bellinger
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target: Re-instate sess_wait_list for target_wait_for_sess_cmds 



Switch back to pre commit 1c7b13fe list splicing logic for active I/O
shutdown with tcm_qla2xxx + ib_srpt fabrics.

The original commit was done under the incorrect assumption that it's safe to
walk se_sess->sess_cmd_list unprotected in target_wait_for_sess_cmds() after
sess->sess_tearing_down = 1 has been set by target_sess_cmd_list_set_waiting()
during session shutdown.

So instead of adding sess->sess_cmd_lock protection around sess->sess_cmd_list
during target_wait_for_sess_cmds(), switch back to sess->sess_wait_list to
allow wait_for_completion() + TFO->release_cmd() to occur without having to
walk ->sess_cmd_list after the list_splice.

Also add a check to exit if target_sess_cmd_list_set_waiting() has already
been called, and add a WARN_ON to check for any fabric bug where new se_cmds
are added to sess->sess_cmd_list after sess->sess_tearing_down = 1 has already
been set.

Cc: Joern Engel <joern@logfs.org>
Cc: Roland Dreier <roland@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent be646c2d

drivers/target/target_core_transport.c

+14 −4
Original line number Diff line number Diff line
@@ -221,6 +221,7 @@ struct se_session *transport_init_session(void) 
	INIT_LIST_HEAD(&se_sess->sess_list);

	INIT_LIST_HEAD(&se_sess->sess_acl_list);

	INIT_LIST_HEAD(&se_sess->sess_cmd_list);

	INIT_LIST_HEAD(&se_sess->sess_wait_list);

	spin_lock_init(&se_sess->sess_cmd_lock);

	kref_init(&se_sess->sess_kref);
@@ -2250,11 +2251,14 @@ void target_sess_cmd_list_set_waiting(struct se_session *se_sess) 
	unsigned long flags;



	spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);



	WARN_ON(se_sess->sess_tearing_down);

	if (se_sess->sess_tearing_down) {

		spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);

		return;

	}

	se_sess->sess_tearing_down = 1;

	list_splice_init(&se_sess->sess_cmd_list, &se_sess->sess_wait_list);



	list_for_each_entry(se_cmd, &se_sess->sess_cmd_list, se_cmd_list)

	list_for_each_entry(se_cmd, &se_sess->sess_wait_list, se_cmd_list)

		se_cmd->cmd_wait_set = 1;



	spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
@@ -2267,9 +2271,10 @@ EXPORT_SYMBOL(target_sess_cmd_list_set_waiting); 
void target_wait_for_sess_cmds(struct se_session *se_sess)

{

	struct se_cmd *se_cmd, *tmp_cmd;

	unsigned long flags;



	list_for_each_entry_safe(se_cmd, tmp_cmd,

				&se_sess->sess_cmd_list, se_cmd_list) {

				&se_sess->sess_wait_list, se_cmd_list) {

		list_del(&se_cmd->se_cmd_list);



		pr_debug("Waiting for se_cmd: %p t_state: %d, fabric state:"
@@ -2283,6 +2288,11 @@ void target_wait_for_sess_cmds(struct se_session *se_sess) 


		se_cmd->se_tfo->release_cmd(se_cmd);

	}



	spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);

	WARN_ON(!list_empty(&se_sess->sess_cmd_list));

	spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);



}

EXPORT_SYMBOL(target_wait_for_sess_cmds);

include/target/target_core_base.h

+1 −0
Original line number Diff line number Diff line
@@ -543,6 +543,7 @@ struct se_session { 
	struct list_head	sess_list;

	struct list_head	sess_acl_list;

	struct list_head	sess_cmd_list;

	struct list_head	sess_wait_list;

	spinlock_t		sess_cmd_lock;

	struct kref		sess_kref;

};