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iscsi-target: Fix incorrect np->np_thread NULL assignment

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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 patch moves the np->np_thread NULL assignment into
iscsit_del_np(), after kthread_stop() has completed. It also
removes the signal_pending() + np_state check, and only
exits when kthread_should_stop() is true.

Reported-by: Hannes Reinecke <hare@suse.de>
Cc: <stable@vger.kernel.org> #3.12+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Nicholas Bellinger
2013-12-11 15:45:32 -08:00
parent 63832aabec
commit db6077fd0b
2 changed files with 1 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/target/iscsi/iscsi_target.c
View File

@@ -465,6 +465,7 @@ int iscsit_del_np(struct iscsi_np *np)
*/ */
send_sig(SIGINT, np->np_thread, 1); send_sig(SIGINT, np->np_thread, 1);
kthread_stop(np->np_thread); kthread_stop(np->np_thread);
np->np_thread = NULL;
} }
np->np_transport->iscsit_free_np(np); np->np_transport->iscsit_free_np(np);

6
drivers/target/iscsi/iscsi_target_login.c
View File

@@ -1403,11 +1403,6 @@ old_sess_out:
out: out:
stop = kthread_should_stop(); 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);
spin_unlock_bh(&np->np_thread_lock);
}
/* Wait for another socket.. */ /* Wait for another socket.. */
if (!stop) if (!stop)
return 1; return 1;
@@ -1415,7 +1410,6 @@ exit:
iscsi_stop_login_thread_timer(np); iscsi_stop_login_thread_timer(np);
spin_lock_bh(&np->np_thread_lock); spin_lock_bh(&np->np_thread_lock);
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); spin_unlock_bh(&np->np_thread_lock);
return 0; return 0;