iscsi-target: Always wait for kthread_should_stop() before kthread exit
authorJiang Yi <jiangyilism@gmail.com>
Tue, 16 May 2017 09:57:55 +0000 (17:57 +0800)
committerNicholas Bellinger <nab@linux-iscsi.org>
Wed, 31 May 2017 22:12:57 +0000 (15:12 -0700)
commit5e0cf5e6c43b9e19fc0284f69e5cd2b4a47523b0
tree7b1807ba795acf651f2599442806f7f96649daf1
parent25cdda95fda78d22d44157da15aa7ea34be3c804
iscsi-target: Always wait for kthread_should_stop() before kthread exit

There are three timing problems in the kthread usages of iscsi_target_mod:

 - np_thread of struct iscsi_np
 - rx_thread and tx_thread of struct iscsi_conn

In iscsit_close_connection(), it calls

 send_sig(SIGINT, conn->tx_thread, 1);
 kthread_stop(conn->tx_thread);

In conn->tx_thread, which is iscsi_target_tx_thread(), when it receive
SIGINT the kthread will exit without checking the return value of
kthread_should_stop().

So if iscsi_target_tx_thread() exit right between send_sig(SIGINT...)
and kthread_stop(...), the kthread_stop() will try to stop an already
stopped kthread.

This is invalid according to the documentation of kthread_stop().

(Fix -ECONNRESET logout handling in iscsi_target_tx_thread and
 early iscsi_target_rx_thread failure case - nab)

Signed-off-by: Jiang Yi <jiangyilism@gmail.com>
Cc: <stable@vger.kernel.org> # v3.12+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
drivers/target/iscsi/iscsi_target.c
drivers/target/iscsi/iscsi_target_erl0.c
drivers/target/iscsi/iscsi_target_erl0.h
drivers/target/iscsi/iscsi_target_login.c