X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=kernel%2Fptrace.c;h=c7e8ed99c953d282a0cbddac2d558a5927dbfeae;hb=986d4e4637c85011e94a40cad15301edbf7a7c03;hp=a46c40bfb5f669f04f6b42c8c06ea0c61ba63360;hpb=96597f605d63ec328b9664404b419b28fe2eb5d1;p=firefly-linux-kernel-4.4.55.git

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index a46c40bfb5f6..c7e8ed99c953 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -151,11 +151,17 @@ static void ptrace_unfreeze_traced(struct task_struct *task)
 
 	WARN_ON(!task->ptrace || task->parent != current);
 
+	/*
+	 * PTRACE_LISTEN can allow ptrace_trap_notify to wake us up remotely.
+	 * Recheck state under the lock to close this race.
+	 */
 	spin_lock_irq(&task->sighand->siglock);
-	if (__fatal_signal_pending(task))
-		wake_up_state(task, __TASK_TRACED);
-	else
-		task->state = TASK_TRACED;
+	if (task->state == __TASK_TRACED) {
+		if (__fatal_signal_pending(task))
+			wake_up_state(task, __TASK_TRACED);
+		else
+			task->state = TASK_TRACED;
+	}
 	spin_unlock_irq(&task->sighand->siglock);
 }