signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_t…

…hread() 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 <[email protected]> Reviewed-by: Tejun Heo <[email protected]> Cc: David Woodhouse <[email protected]> Cc: Felipe Balbi <[email protected]> Cc: Markus Pargmann <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
chewitt · Nov 7, 2015 · 9a13049 · 9a13049
1 parent be0e6f2
commit 9a13049
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Showing 2 changed files with 11 additions and 2 deletions.
diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c
@@ -132,8 +132,7 @@ static int jffs2_garbage_collect_thread(void *_c)
 			case SIGSTOP:
 				jffs2_dbg(1, "%s(): SIGSTOP received\n",
 					  __func__);
-				set_current_state(TASK_STOPPED);
-				schedule();
+				kernel_signal_stop();
 				break;
 
 			case SIGKILL:

diff --git a/include/linux/sched.h b/include/linux/sched.h
@@ -2475,6 +2475,16 @@ static inline int kernel_dequeue_signal(siginfo_t *info)
 	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 int send_sig_info(int, struct siginfo *, struct task_struct *);
 extern int force_sigsegv(int, struct task_struct *);