2008-03-02 18:42:10

by Oleg Nesterov

Subject: [PATCH 3/3] exit_notify: fix kill_orphaned_pgrp() usage with mt exit

1. exit_notify() always calls kill_orphaned_pgrp(). This is wrong, we
should do this only when the whole process exits.

2. exit_notify() uses "current" as "ignored_task", obviously wrong.
Use ->group_leader instead.

Test case:

void hup(int sig)
{
printf("HUP received\n");
}

void *tfunc(void *arg)
{
sleep(2);
printf("sub-thread exited\n");
return NULL;
}

int main(int argc, char *argv[])
{
if (!fork()) {
signal(SIGHUP, hup);
kill(getpid(), SIGSTOP);
exit(0);
}

pthread_t thr;
pthread_create(&thr, NULL, tfunc, NULL);

sleep(1);
printf("main thread exited\n");
syscall(__NR_exit, 0);

return 0;
}

output:

main thread exited
HUP received
Hangup

With this patch the output is:

main thread exited
sub-thread exited
HUP received

Signed-off-by: Oleg Nesterov <[email protected]>

--- 25/kernel/exit.c~3_OG_EXIT 2008-03-02 19:42:56.000000000 +0300
+++ 25/kernel/exit.c 2008-03-02 21:21:51.000000000 +0300
@@ -754,7 +754,7 @@ static void forget_original_parent(struc
* Send signals to all our closest relatives so that they know
* to properly mourn us..
*/
-static void exit_notify(struct task_struct *tsk)
+static void exit_notify(struct task_struct *tsk, int group_dead)
{
int state;

@@ -770,7 +770,8 @@ static void exit_notify(struct task_stru
exit_task_namespaces(tsk);

write_lock_irq(&tasklist_lock);
- kill_orphaned_pgrp(tsk, NULL);
+ if (group_dead)
+ kill_orphaned_pgrp(tsk->group_leader, NULL);

/* Let father know we died
*
@@ -985,7 +986,7 @@ NORET_TYPE void do_exit(long code)
module_put(tsk->binfmt->module);

proc_exit_connector(tsk);
- exit_notify(tsk);
+ exit_notify(tsk, group_dead);
#ifdef CONFIG_NUMA
mpol_free(tsk->mempolicy);
tsk->mempolicy = NULL;