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author | Nicholas Bellinger <nab@linux-iscsi.org> | 2018-10-10 03:23:10 +0000 |
---|---|---|
committer | Martin K. Petersen <martin.petersen@oracle.com> | 2018-10-16 00:11:13 -0400 |
commit | 38fe73cc2c96fbc9942b07220f2a4f1bab37392d (patch) | |
tree | e24c932a386effe4e704014dff2c50144f96ed19 /drivers/target/target_core_transport.c | |
parent | 25ab0bc334b43bbbe4eabc255006ce42a9424da2 (diff) | |
download | linux-stable-38fe73cc2c96fbc9942b07220f2a4f1bab37392d.tar.gz linux-stable-38fe73cc2c96fbc9942b07220f2a4f1bab37392d.tar.bz2 linux-stable-38fe73cc2c96fbc9942b07220f2a4f1bab37392d.zip |
scsi: target: Fix target_wait_for_sess_cmds breakage with active signals
With the addition of commit 00d909a10710 ("scsi: target: Make the session
shutdown code also wait for commands that are being aborted") in v4.19-rc, it
incorrectly assumes no signals will be pending for task_struct executing the
normal session shutdown and I/O quiesce code-path.
For example, iscsi-target and iser-target issue SIGINT to all kthreads as part
of session shutdown. This has been the behaviour since day one.
As-is when signals are pending with se_cmds active in se_sess->sess_cmd_list,
wait_event_interruptible_lock_irq_timeout() returns a negative number and
immediately kills the machine because of the do while (ret <= 0) loop that was
added in commit 00d909a107 to spin while backend I/O is taking any amount of
extended time (say 30 seconds) to complete.
Here's what it looks like in action with debug plus delayed backend I/O
completion:
[ 4951.909951] se_sess: 000000003e7e08fa before target_wait_for_sess_cmds
[ 4951.914600] target_wait_for_sess_cmds: signal_pending: 1
[ 4951.918015] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 0
[ 4951.921639] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 1
[ 4951.921944] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 2
[ 4951.921944] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 3
[ 4951.921944] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 4
[ 4951.921944] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 5
[ 4951.921944] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 6
[ 4951.921944] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 7
[ 4951.921944] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 8
[ 4951.921944] wait_event_interruptible_lock_irq_timeout ret: -512 signal_pending: 1 loop count: 9
... followed by the usual RCU CPU stalls and deadlock.
There was never a case pre commit 00d909a107 where
wait_for_complete(&se_cmd->cmd_wait_comp) was able to be interrupted, so to
address this for v4.19+ moving forward go ahead and use
wait_event_lock_irq_timeout() instead so new code works with all fabric
drivers.
Also for commit 00d909a107, fix a minor regression in
target_release_cmd_kref() to only wake_up the new se_sess->cmd_list_wq only
when shutdown has actually been triggered via se_sess->sess_tearing_down.
Fixes: 00d909a10710 ("scsi: target: Make the session shutdown code also wait for commands that are being aborted")
Cc: <stable@vger.kernel.org> # v4.19+
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Tested-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Reviewed-by: Bryant G. Ly <bly@catalogicsoftware.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/target/target_core_transport.c')
-rw-r--r-- | drivers/target/target_core_transport.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 86c0156e6c88..fc3093d21b96 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -2754,7 +2754,7 @@ static void target_release_cmd_kref(struct kref *kref) if (se_sess) { spin_lock_irqsave(&se_sess->sess_cmd_lock, flags); list_del_init(&se_cmd->se_cmd_list); - if (list_empty(&se_sess->sess_cmd_list)) + if (se_sess->sess_tearing_down && list_empty(&se_sess->sess_cmd_list)) wake_up(&se_sess->cmd_list_wq); spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags); } @@ -2907,7 +2907,7 @@ void target_wait_for_sess_cmds(struct se_session *se_sess) spin_lock_irq(&se_sess->sess_cmd_lock); do { - ret = wait_event_interruptible_lock_irq_timeout( + ret = wait_event_lock_irq_timeout( se_sess->cmd_list_wq, list_empty(&se_sess->sess_cmd_list), se_sess->sess_cmd_lock, 180 * HZ); |