[PATCH V6 05/10] signal: Perfom autoreap for PF_USER_WORKER

Mike Christie
2021-11-29T19:50:11Z

Userspace doesn't know about PF_USER_WORKER threads, so it can't do wait
to clean them up. For cases like where qemu will do dynamic/hot add/remove
of vhost devices, then we need to auto reap the thread like was done for
the kthread case, because qemu does not know what API the kernel/vhost
layer is using.

This has us do autoreaping for these threads similar to when the parent
ignores SIGCHLD and for kthreads.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
kernel/signal.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index a629b11bf3e0..4ce2cc195269 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2071,9 +2071,9 @@ bool do_notify_parent(struct task_struct *tsk, int sig)

psig = tsk->parent->sighand;
spin_lock_irqsave(&psig->siglock, flags);
- if (!tsk->ptrace && sig == SIGCHLD &&
+ if (!tsk->ptrace && (tsk->flags & PF_USER_WORKER || (sig == SIGCHLD &&
(psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
- (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
+ (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))))) {
/*
* We are exiting and our parent doesn't care. POSIX.1
* defines special semantics for setting SIGCHLD to SIG_IGN
--
2.25.1