diff options
| author | Roland Dreier <roland@purestorage.com> | 2012-10-31 09:16:46 -0700 |
|---|---|---|
| committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2012-11-01 00:38:44 -0700 |
| commit | d5627acba9ae584cf4928af19f7ddf5f6837de32 (patch) | |
| tree | 4247438e4a6ab7ef76c68a6d35093db95eca1451 /drivers/target/iscsi/iscsi_target.c | |
| parent | 3e03989b5868acf69a391a424dc71fcd6cc48167 (diff) | |
iscsi-target: Fix missed wakeup race in TX thread
The sleeping code in iscsi_target_tx_thread() is susceptible to the classic
missed wakeup race:
- TX thread finishes handle_immediate_queue() and handle_response_queue(),
thinks both queues are empty.
- Another thread adds a queue entry and does wake_up_process(), which does
nothing because the TX thread is still awake.
- TX thread does schedule_timeout() and sleeps forever.
In practice this can kill an iSCSI connection if for example an initiator
does single-threaded writes and the target misses the wakeup window when
queueing an R2T; in this case the connection will be stuck until the
initiator loses patience and does some task management operation (or kills
the connection entirely).
Fix this by converting to wait_event_interruptible(), which does not
suffer from this sort of race.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Cc: Andy Grover <agrover@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target/iscsi/iscsi_target.c')
| -rw-r--r-- | drivers/target/iscsi/iscsi_target.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index d6ce2182e672..035c2c762537 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -3719,7 +3719,9 @@ restart: */ iscsit_thread_check_cpumask(conn, current, 1); - schedule_timeout_interruptible(MAX_SCHEDULE_TIMEOUT); + wait_event_interruptible(conn->queues_wq, + !iscsit_conn_all_queues_empty(conn) || + ts->status == ISCSI_THREAD_SET_RESET); if ((ts->status == ISCSI_THREAD_SET_RESET) || signal_pending(current)) |