[059/141] target: Re-instate sess_wait_list for target_wait_for_sess_cmds

Steven Rostedt
2013-07-03T18:47:43Z

[-- Attachment #1: 0059-target-Re-instate-sess_wait_list-for-target_wait_for.patch --]
[-- Type: text/plain, Size: 3792 bytes --]

3.6.11.6 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Nicholas Bellinger <nab@linux-iscsi.org>

[ Upstream commit 9b31a328e344e62e7cc98ae574edcb7b674719bb ]

Switch back to pre commit 1c7b13fe652 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>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
drivers/target/target_core_transport.c | 18 ++++++++++++++----
include/target/target_core_base.h | 1 +
2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 140bfb3..725ab56 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -232,6 +232,7 @@ 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);

@@ -2469,11 +2470,14 @@ 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);
@@ -2490,9 +2494,10 @@ void target_wait_for_sess_cmds(
{
struct se_cmd *se_cmd, *tmp_cmd;
bool rc = false;
+ 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:"
@@ -2520,6 +2525,11 @@ void target_wait_for_sess_cmds(

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);

diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 5be8937..71f7662 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -613,6 +613,7 @@ 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;
};
--
1.7.10.4