From: Mikulas Patocka Date: Mon, 23 Jun 2014 17:42:37 +0000 (-0400) Subject: iscsi-target: fix iscsit_del_np deadlock on unload X-Git-Tag: omap-for-v3.17/soc-cleanup~32^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=81a9c5e72bdf7109a65102ca61d8cbd722cf4021;p=pandora-kernel.git iscsi-target: fix iscsit_del_np deadlock on unload On uniprocessor preemptible kernel, target core deadlocks on unload. The following events happen: * iscsit_del_np is called * it calls send_sig(SIGINT, np->np_thread, 1); * the scheduler switches to the np_thread * the np_thread is woken up, it sees that kthread_should_stop() returns false, so it doesn't terminate * the np_thread clears signals with flush_signals(current); and goes back to sleep in iscsit_accept_np * the scheduler switches back to iscsit_del_np * iscsit_del_np calls kthread_stop(np->np_thread); * the np_thread is waiting in iscsit_accept_np and it doesn't respond to kthread_stop The deadlock could be resolved if the administrator sends SIGINT signal to the np_thread with killall -INT iscsi_np The reproducible deadlock was introduced in commit db6077fd0b7dd41dc6ff18329cec979379071f87, but the thread-stopping code was racy even before. This patch fixes the problem. Using kthread_should_stop to stop the np_thread is unreliable, so we test np_thread_state instead. If np_thread_state equals ISCSI_NP_THREAD_SHUTDOWN, the thread exits. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Signed-off-by: Nicholas Bellinger --- Reading git-diff-tree failed