When shutting down a target there is a race condition between
iscsit_del_np() and __iscsi_target_login_thread().
The latter sets the thread pointer to NULL, and the former
tries to issue kthread_stop() on that pointer without any
synchronization.
This patchs adds proper synchronization pointer between those
calls to ensure that a) the thread is correctly terminate and
b) kthread_stop() isn't called with a NULL pointer.
In the long run iscsi_target_login_thread() should be converted
into a workqueue.
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
---
drivers/target/iscsi/iscsi_target.c | 12 +++++++++---
drivers/target/iscsi/iscsi_target_login.c | 9 ++++++---
2 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index bf76fc4..c7bf3c9 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -457,15 +457,21 @@ int iscsit_del_np(struct iscsi_np *np)
}
np->np_thread_state = ISCSI_NP_THREAD_SHUTDOWN;
spin_unlock_bh(&np->np_thread_lock);
-
- if (np->np_thread) {
+ /* Give __iscsi_target_login_thread() a chance to run */
+ schedule();
+ spin_lock_bh(&np->np_thread_lock);
+ if ((np->np_thread_state == ISCSI_NP_THREAD_SHUTDOWN)
+ && np->np_thread) {
+ np->np_thread_state = ISCSI_NP_THREAD_EXIT;
+ spin_unlock_bh(&np->np_thread_lock);
/*
* We need to send the signal to wakeup Linux/Net
* which may be sleeping in sock_accept()..
*/
send_sig(SIGINT, np->np_thread, 1);
kthread_stop(np->np_thread);
- }
+ } else
+ spin_unlock_bh(&np->np_thread_lock);
np->np_transport->iscsit_free_np(np);
diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c
index 4eb93b2..b375d26 100644
--- a/drivers/target/iscsi/iscsi_target_login.c
+++ b/drivers/target/iscsi/iscsi_target_login.c
@@ -1405,7 +1405,8 @@ out:
stop = kthread_should_stop();
if (!stop && signal_pending(current)) {
spin_lock_bh(&np->np_thread_lock);
- stop = (np->np_thread_state == ISCSI_NP_THREAD_SHUTDOWN);
+ stop = (np->np_thread_state == ISCSI_NP_THREAD_SHUTDOWN ||
+ np->np_thread_state == ISCSI_NP_THREAD_EXIT);
spin_unlock_bh(&np->np_thread_lock);
}
/* Wait for another socket.. */
@@ -1414,8 +1415,10 @@ out:
exit:
iscsi_stop_login_thread_timer(np);
spin_lock_bh(&np->np_thread_lock);
- np->np_thread_state = ISCSI_NP_THREAD_EXIT;
- np->np_thread = NULL;
+ if (np->np_thread_state != ISCSI_NP_THREAD_EXIT) {
+ np->np_thread_state = ISCSI_NP_THREAD_EXIT;
+ np->np_thread = NULL;
+ }
spin_unlock_bh(&np->np_thread_lock);
return 0;
--
1.7.12.4
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