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Commit 9a13049e authored Nov 06, 2015 by Oleg Nesterov Committed by Linus Torvalds Nov 06, 2015

signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread()

jffs2_garbage_collect_thread() can race with SIGCONT and sleep in
TASK_STOPPED state after it was already sent. Add the new helper,
kernel_signal_stop(), which does this correctly.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent be0e6f29

fs/jffs2/background.c

+1 −2

Original line number	Original line	Diff line number	Diff line
	@@ -132,8 +132,7 @@ static int jffs2_garbage_collect_thread(void *_c)
	case SIGSTOP:		case SIGSTOP:
	jffs2_dbg(1, "%s(): SIGSTOP received\n",		jffs2_dbg(1, "%s(): SIGSTOP received\n",
	__func__);		__func__);
	set_current_state(TASK_STOPPED);		kernel_signal_stop();
	schedule();
	break;		break;

	case SIGKILL:		case SIGKILL:

include/linux/sched.h

+10 −0

Original line number	Original line	Diff line number	Diff line
	@@ -2475,6 +2475,16 @@ static inline int kernel_dequeue_signal(siginfo_t *info)
	return ret;		return ret;
	}		}

			static inline void kernel_signal_stop(void)
			{
			spin_lock_irq(&current->sighand->siglock);
			if (current->jobctl & JOBCTL_STOP_DEQUEUED)
			__set_current_state(TASK_STOPPED);
			spin_unlock_irq(&current->sighand->siglock);

			schedule();
			}

	extern void release_task(struct task_struct * p);		extern void release_task(struct task_struct * p);
	extern int send_sig_info(int, struct siginfo , struct task_struct );		extern int send_sig_info(int, struct siginfo , struct task_struct );
	extern int force_sigsegv(int, struct task_struct *);		extern int force_sigsegv(int, struct task_struct *);