signal: Use PIDTYPE_TGID to clearly store where file signals will be sent
When f_setown is called a pid and a pid type are stored. Replace the use
of PIDTYPE_PID with PIDTYPE_TGID as PIDTYPE_TGID goes to the entire thread
group. Replace the use of PIDTYPE_MAX with PIDTYPE_PID as PIDTYPE_PID now
is only for a thread.
Update the users of __f_setown to use PIDTYPE_TGID instead of
PIDTYPE_PID.
For now the code continues to capture task_pid (when task_tgid would
really be appropriate), and iterate on PIDTYPE_PID (even when type ==
PIDTYPE_TGID) out of an abundance of caution to preserve existing
behavior.
Oleg Nesterov suggested using the test to ensure we use PIDTYPE_PID
for tgid lookup also be used to avoid taking the tasklist lock.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a192a01..9958b70 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -3216,7 +3216,7 @@ static int tun_chr_fasync(int fd, struct file *file, int on)
goto out;
if (on) {
- __f_setown(file, task_pid(current), PIDTYPE_PID, 0);
+ __f_setown(file, task_pid(current), PIDTYPE_TGID, 0);
tfile->flags |= TUN_FASYNC;
} else
tfile->flags &= ~TUN_FASYNC;