exit_notify: fix kill_orphaned_pgrp() usage with mt exit
authorOleg Nesterov <oleg@tv-sign.ru>
Sun, 2 Mar 2008 18:44:44 +0000 (21:44 +0300)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Mon, 3 Mar 2008 22:53:16 +0000 (14:53 -0800)
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 <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/exit.c

index 41c1edace97a34fc44d5725ed4544ad07bf33dd5..cd20bf07e9e3b7bb2260c4a5939642c9e4bcb0a5 100644 (file)
@@ -750,7 +750,7 @@ static void forget_original_parent(struct task_struct *father)
  * 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;
 
@@ -766,7 +766,8 @@ static void exit_notify(struct task_struct *tsk)
        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
         *
@@ -981,7 +982,7 @@ 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;