From d5627acba9ae584cf4928af19f7ddf5f6837de32 Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Wed, 31 Oct 2012 09:16:46 -0700 Subject: 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 Cc: Andy Grover Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: stable@vger.kernel.org Signed-off-by: Nicholas Bellinger --- drivers/target/iscsi/iscsi_target_util.h | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/target/iscsi/iscsi_target_util.h') diff --git a/drivers/target/iscsi/iscsi_target_util.h b/drivers/target/iscsi/iscsi_target_util.h index 44054bd35437..894d0f837924 100644 --- a/drivers/target/iscsi/iscsi_target_util.h +++ b/drivers/target/iscsi/iscsi_target_util.h @@ -25,6 +25,7 @@ extern struct iscsi_queue_req *iscsit_get_cmd_from_immediate_queue(struct iscsi_ extern void iscsit_add_cmd_to_response_queue(struct iscsi_cmd *, struct iscsi_conn *, u8); extern struct iscsi_queue_req *iscsit_get_cmd_from_response_queue(struct iscsi_conn *); extern void iscsit_remove_cmd_from_tx_queues(struct iscsi_cmd *, struct iscsi_conn *); +extern bool iscsit_conn_all_queues_empty(struct iscsi_conn *); extern void iscsit_free_queue_reqs_for_conn(struct iscsi_conn *); extern void iscsit_release_cmd(struct iscsi_cmd *); extern void iscsit_free_cmd(struct iscsi_cmd *); -- cgit v1.2.3