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 <[email protected]>
Cc: Andy Grover <[email protected]>
Cc: Hannes Reinecke <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: [email protected]
Signed-off-by: Nicholas Bellinger <[email protected]>

0 files changed, 0 insertions, 0 deletions