From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Wed, 15 May 2019 12:33:50 -0500
Subject: [PATCH] signal/cifs: Fix cifs_put_tcp_session to call send_sig
 instead of force_sig
Git-commit: 72abe3bcf0911d69b46c1e8bdb5612675e0ac42c
Patch-mainline: v5.2-rc3
References: bsc#1144333

The locking in force_sig_info is not prepared to deal with a task that
exits or execs (as sighand may change).  The is not a locking problem
in force_sig as force_sig is only built to handle synchronous
exceptions.

Further the function force_sig_info changes the signal state if the
signal is ignored, or blocked or if SIGNAL_UNKILLABLE will prevent the
delivery of the signal.  The signal SIGKILL can not be ignored and can
not be blocked and SIGNAL_UNKILLABLE won't prevent it from being
delivered.

So using force_sig rather than send_sig for SIGKILL is confusing
and pointless.

Because it won't impact the sending of the signal and and because
using force_sig is wrong, replace force_sig with send_sig.

Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Jeff Layton <jlayton@primarydata.com>
Cc: Steve French <smfrench@gmail.com>
Fixes: a5c3e1c725af ("Revert "cifs: No need to send SIGKILL to demux_thread during umount"")
Fixes: e7ddee9037e7 ("cifs: disable sharing session and tcon and add new TCP sharing code")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
 fs/cifs/connect.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 8c4121da624e..ed22bffb3fcc 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2629,7 +2629,7 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 
 	task = xchg(&server->tsk, NULL);
 	if (task)
-		force_sig(SIGKILL, task);
+		send_sig(SIGKILL, task, 1);
 }
 
 static struct TCP_Server_Info *
-- 
2.22.0