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author | Mikulas Patocka <mpatocka@redhat.com> | 2014-06-23 19:42:37 +0200 |
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committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2014-06-28 08:23:35 +0200 |
commit | 81a9c5e72bdf7109a65102ca61d8cbd722cf4021 (patch) | |
tree | 23e1accddfc6aedef0186db3061fe820b023dfc7 /drivers/crypto | |
parent | iovec: move memcpy_from/toiovecend to lib/iovec.c (diff) | |
download | linux-81a9c5e72bdf7109a65102ca61d8cbd722cf4021.tar.xz linux-81a9c5e72bdf7109a65102ca61d8cbd722cf4021.zip |
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 <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/crypto')
0 files changed, 0 insertions, 0 deletions