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target: Re-instate sess_wait_list for target_wait_for_sess_cmds 

Switch back to pre commit 1c7b13fe65 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: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Nicholas Bellinger 2013-05-15 00:52:44 -07:00
parent be646c2d2b
commit 9b31a328e3
2 changed files with 15 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/target/target_core_transport.c
View File

@ -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);

1
include/target/target_core_base.h
View File

@ -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;
};