@@ -3733,7 +3733,9 @@ 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))
@@ -485,6 +485,7 @@ struct iscsi_tmr_req {
};
struct iscsi_conn {
+ wait_queue_head_t queues_wq;
/* Authentication Successful for this connection */
u8 auth_complete;
/* State connection is currently in */
@@ -45,6 +45,7 @@ extern spinlock_t sess_idr_lock;
static int iscsi_login_init_conn(struct iscsi_conn *conn)
{
+ init_waitqueue_head(&conn->queues_wq);
INIT_LIST_HEAD(&conn->conn_list);
INIT_LIST_HEAD(&conn->conn_cmd_list);
INIT_LIST_HEAD(&conn->immed_queue_list);
@@ -488,7 +488,7 @@ void iscsit_add_cmd_to_immediate_queue(
atomic_set(&conn->check_immediate_queue, 1);
spin_unlock_bh(&conn->immed_queue_lock);
- wake_up_process(conn->thread_set->tx_thread);
+ wake_up(&conn->queues_wq);
}
struct iscsi_queue_req *iscsit_get_cmd_from_immediate_queue(struct iscsi_conn *conn)
@@ -562,7 +562,7 @@ void iscsit_add_cmd_to_response_queue(
atomic_inc(&cmd->response_queue_count);
spin_unlock_bh(&conn->response_queue_lock);
- wake_up_process(conn->thread_set->tx_thread);
+ wake_up(&conn->queues_wq);
}
struct iscsi_queue_req *iscsit_get_cmd_from_response_queue(struct iscsi_conn *conn)
@@ -616,6 +616,24 @@ static void iscsit_remove_cmd_from_response_queue(
}
}
+bool iscsit_conn_all_queues_empty(struct iscsi_conn *conn)
+{
+ bool empty;
+
+ spin_lock_bh(&conn->immed_queue_lock);
+ empty = list_empty(&conn->immed_queue_list);
+ spin_unlock_bh(&conn->immed_queue_lock);
+
+ if (!empty)
+ return empty;
+
+ spin_lock_bh(&conn->response_queue_lock);
+ empty = list_empty(&conn->response_queue_list);
+ spin_unlock_bh(&conn->response_queue_lock);
+
+ return empty;
+}
+
void iscsit_free_queue_reqs_for_conn(struct iscsi_conn *conn)
{
struct iscsi_queue_req *qr, *qr_tmp;
@@ -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 *);
This is a note to let you know that I have just added a patch titled iscsi-target: Fix missed wakeup race in TX thread to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Herton ------ From eca09e9f40b10929b487ca74481cf5df3d35636c Mon Sep 17 00:00:00 2001 From: Roland Dreier <roland@purestorage.com> Date: Wed, 31 Oct 2012 09:16:46 -0700 Subject: [PATCH] iscsi-target: Fix missed wakeup race in TX thread X-Extended-Stable: 3.5 commit d5627acba9ae584cf4928af19f7ddf5f6837de32 upstream. 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> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com> --- drivers/target/iscsi/iscsi_target.c | 4 +++- drivers/target/iscsi/iscsi_target_core.h | 1 + drivers/target/iscsi/iscsi_target_login.c | 1 + drivers/target/iscsi/iscsi_target_util.c | 22 ++++++++++++++++++++-- drivers/target/iscsi/iscsi_target_util.h | 1 + 5 files changed, 26 insertions(+), 3 deletions(-) -- 1.7.9.5