kernel_5.10 no rt

hc

2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f

 kernel/fs/eventfd.c
..
..
@@ -25,6 +25,8 @@
25
25
 #include <linux/idr.h>
26
26
 #include <linux/uio.h>
27
27
 
28
+DEFINE_PER_CPU(int, eventfd_wake_count);
29
+
28
30
 static DEFINE_IDA(eventfd_ida);
29
31
 
30
32
 struct eventfd_ctx {
..
..
@@ -51,21 +53,21 @@
51
53
 	 * Deadlock or stack overflow issues can happen if we recurse here
52
54
 	 * through waitqueue wakeup handlers. If the caller users potentially
53
55
 	 * nested waitqueues with custom wakeup handlers, then it should
54
-	 * check eventfd_signal_allowed() before calling this function. If
55
-	 * it returns false, the eventfd_signal() call should be deferred to a
56
+	 * check eventfd_signal_count() before calling this function. If
57
+	 * it returns true, the eventfd_signal() call should be deferred to a
56
58
 	 * safe context.
57
59
 	 */
58
-	if (WARN_ON_ONCE(current->in_eventfd_signal))
60
+	if (WARN_ON_ONCE(this_cpu_read(eventfd_wake_count)))
59
61
 		return 0;
60
62
 
61
63
 	spin_lock_irqsave(&ctx->wqh.lock, flags);
62
-	current->in_eventfd_signal = 1;
64
+	this_cpu_inc(eventfd_wake_count);
63
65
 	if (ULLONG_MAX - ctx->count < n)
64
66
 		n = ULLONG_MAX - ctx->count;
65
67
 	ctx->count += n;
66
68
 	if (waitqueue_active(&ctx->wqh))
67
69
 		wake_up_locked_poll(&ctx->wqh, EPOLLIN | mask);
68
-	current->in_eventfd_signal = 0;
70
+	this_cpu_dec(eventfd_wake_count);
69
71
 	spin_unlock_irqrestore(&ctx->wqh.lock, flags);
70
72
 
71
73
 	return n;