commit 9a13049e83f346cb1cbd60c64e520a73c396af16
author Oleg Nesterov <oleg@redhat.com> Fri Nov 06 16:32:25 2015 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> Fri Nov 06 17:50:42 2015 -0800
tree 11a2ac2ac28dbfa477d5b4f1e14a2173b4867a8f
parent be0e6f290f78b84a3b21b8c8c46819c4514fe632

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>

include/linux/sched.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3d54924..4069feb 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2475,6 +2475,16 @@
 	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 *);