On Tue, Jul 16, 2019 at 1:15 AM Sasha Levin sashal@kernel.org wrote:
From: "Eric W. Biederman" ebiederm@xmission.com
[ 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.
I think this patch broke the cifs module. The issue is that the use count is now not updated properly and thus it is no longer possible to rmmod the module.
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