Note that this patch causes a regression (removing cifs module fails, due to unmount leaking a thread with this change).
We are testing a workaround to cifs.ko which would be needed if this patch were to be backported.
On Wed, Jul 24, 2019 at 2:26 PM Greg Kroah-Hartman gregkh@linuxfoundation.org wrote:
[ Upstream commit 72abe3bcf0911d69b46c1e8bdb5612675e0ac42c ]
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 Signed-off-by: Sasha Levin sashal@kernel.org
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 8dd6637a3cbb..714a359c7c8d 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -2631,7 +2631,7 @@ 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 *
2.20.1