[PATCH] coredump: set ->group_exit_code for other CLONE_VM tasks too

[PATCH] coredump: set ->group_exit_code for other CLONE_VM tasks too

[Oleg Nesterov]

User visible change.

do_coredump() kills all threads which share the same ->mm but only
the coredumping process gets the proper exit_code. Other tasks which
share the same ->mm die "silently" and return status == 0 to parent.

This is historical behaviour, not actually a bug. But I think Frank
Heckenbach rightly dislikes the current behaviour. Simple test-case:

	#include <stdio.h>
	#include <unistd.h>
	#include <signal.h>
	#include <sys/wait.h>

	int main(void)
	{
		int stat;

		if (!fork()) {
			if (!vfork())
				kill(getpid(), SIGQUIT);
		}

		wait(&stat);
		printf("stat=%x\n", stat);
		return 0;
	}

Before this patch it prints "stat=0" despite the fact the child was
killed by SIGQUIT. After this patch the output is "stat=3" which
obviously makes more sense.

Even with this patch, only the task which originates the coredumping
gets "|= 0x80" if the core was actually dumped, but at least the
coredumping signal is visible to do_wait/etc.

Reported-by: Frank Heckenbach <f.heckenbach@fh-soft.de>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---

 fs/exec.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- V1/fs/exec.c~CD_STATUS	2009-12-18 00:20:50.000000000 +0100
+++ V1/fs/exec.c	2010-02-07 17:28:24.000000000 +0100
@@ -1536,12 +1536,13 @@ out:
 	return ispipe;
 }
 
-static int zap_process(struct task_struct *start)
+static int zap_process(struct task_struct *start, int exit_code)
 {
 	struct task_struct *t;
 	int nr = 0;
 
 	start->signal->flags = SIGNAL_GROUP_EXIT;
+	start->signal->group_exit_code = exit_code;
 	start->signal->group_stop_count = 0;
 
 	t = start;
@@ -1566,8 +1567,7 @@ static inline int zap_threads(struct tas
 	spin_lock_irq(&tsk->sighand->siglock);
 	if (!signal_group_exit(tsk->signal)) {
 		mm->core_state = core_state;
-		tsk->signal->group_exit_code = exit_code;
-		nr = zap_process(tsk);
+		nr = zap_process(tsk, exit_code);
 	}
 	spin_unlock_irq(&tsk->sighand->siglock);
 	if (unlikely(nr < 0))
@@ -1616,7 +1616,7 @@ static inline int zap_threads(struct tas
 			if (p->mm) {
 				if (unlikely(p->mm == mm)) {
 					lock_task_sighand(p, &flags);
-					nr += zap_process(p);
+					nr += zap_process(p, exit_code);
 					unlock_task_sighand(p, &flags);
 				}
 				break;

Re: [PATCH] coredump: set ->group_exit_code for other CLONE_VM tasks too

[Américo Wang]

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On Mon, Feb 8, 2010 at 1:16 AM, Oleg Nesterov <oleg@redhat.com> wrote:> User visible change.>> do_coredump() kills all threads which share the same ->mm but only> the coredumping process gets the proper exit_code. Other tasks which> share the same ->mm die "silently" and return status == 0 to parent.>> This is historical behaviour, not actually a bug. But I think Frank> Heckenbach rightly dislikes the current behaviour. Simple test-case:>>        #include <stdio.h>>        #include <unistd.h>>        #include <signal.h>>        #include <sys/wait.h>>>        int main(void)>        {>                int stat;>>                if (!fork()) {>                        if (!vfork())>                                kill(getpid(), SIGQUIT);>                }>>                wait(&stat);>                printf("stat=%x\n", stat);>                return 0;>        }>> Before this patch it prints "stat=0" despite the fact the child was> killed by SIGQUIT. After this patch the output is "stat=3" which> obviously makes more sense.>> Even with this patch, only the task which originates the coredumping> gets "|= 0x80" if the core was actually dumped, but at least the> coredumping signal is visible to do_wait/etc.

Nice changelog!
>> Reported-by: Frank Heckenbach <f.heckenbach@fh-soft.de>> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Thank you!
> --->>  fs/exec.c |    8 ++++---->  1 file changed, 4 insertions(+), 4 deletions(-)>> --- V1/fs/exec.c~CD_STATUS      2009-12-18 00:20:50.000000000 +0100> +++ V1/fs/exec.c        2010-02-07 17:28:24.000000000 +0100> @@ -1536,12 +1536,13 @@ out:>        return ispipe;>  }>> -static int zap_process(struct task_struct *start)> +static int zap_process(struct task_struct *start, int exit_code)>  {>        struct task_struct *t;>        int nr = 0;>>        start->signal->flags = SIGNAL_GROUP_EXIT;> +       start->signal->group_exit_code = exit_code;>        start->signal->group_stop_count = 0;>>        t = start;> @@ -1566,8 +1567,7 @@ static inline int zap_threads(struct tas>        spin_lock_irq(&tsk->sighand->siglock);>        if (!signal_group_exit(tsk->signal)) {>                mm->core_state = core_state;> -               tsk->signal->group_exit_code = exit_code;> -               nr = zap_process(tsk);> +               nr = zap_process(tsk, exit_code);>        }>        spin_unlock_irq(&tsk->sighand->siglock);>        if (unlikely(nr < 0))> @@ -1616,7 +1616,7 @@ static inline int zap_threads(struct tas>                        if (p->mm) {>                                if (unlikely(p->mm == mm)) {>                                        lock_task_sighand(p, &flags);> -                                       nr += zap_process(p);> +                                       nr += zap_process(p, exit_code);>                                        unlock_task_sighand(p, &flags);>                                }>                                break;>>ÿôèº{.nÇ+‰·Ÿ®‰­†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a­¢f£¢·hšïêÿ‘êçz_è®\x03(­éšŽŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨è­Ú&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥

Re: [PATCH] coredump: set ->group_exit_code for other CLONE_VM tasks too

[Roland McGrath]

That seems reasonable to me.

Thanks,
Roland