de_thread()

PATCH RESEND New Oleg Nesterov 1 participant 1 message Oct 16, 2002

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Oleg Nesterov

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2002-10-16 14:19 UTC #0 lore raw

PATCH RESEND 1/1 de_thread()

Hello.

Quoted 8 lines · Oleg Nesterov

Suppose process P in thread group was cloned _without_ CLONE_DETACHED flag. Then another thread, group_leader for simplicity, does exec and calls de_thread(). It kills P via _broadcast_thread_group(). While doing do_exit(), P skips release_task(), because its exit_signal != -1, and becomes TASK_ZOMBIE.

Quoted 4 lines

Then leader calls schedule() with TASK_UNINTERRUPTIBLE in while(oldsig->count > 1) {...} and sleeps forever, because nobody can do wake_up_process(sig->group_exit_task).

This program should hang leaving task in D state.

#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <asm/unistd.h>

#define CLONE_SIGHAND 0x00000800
#define CLONE_THREAD 0x00010000

#define __NR_sys_clone __NR_clone

static inline _syscall2(int,sys_clone, int,flag, void*,stack)

int main(void)

{
	static char stack[1024];
	int pid = sys_clone(CLONE_THREAD | CLONE_SIGHAND | SIGCHLD, stack);

	if (pid < 0) {
		printf("ERR!! clone: %s.\n", strerror(errno));
		return -1;
	}

	if (pid == 0) _exit(0);

	execlp("echo", "echo", "Should not happen.", 0);
	printf("ERR!! exec: %s.\n", strerror(errno));

	return 0;
}

Oleg.