add ax88772_rst

hc

2024-05-10 9999e48639b3cecb08ffb37358bcba3b48161b29

 kernel/fs/eventfd.c
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@@ -25,6 +25,8 @@
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 #include <linux/idr.h>
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 #include <linux/uio.h>
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+DEFINE_PER_CPU(int, eventfd_wake_count);
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+
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 static DEFINE_IDA(eventfd_ida);
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 struct eventfd_ctx {
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@@ -51,21 +53,21 @@
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 	 * Deadlock or stack overflow issues can happen if we recurse here
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 	 * through waitqueue wakeup handlers. If the caller users potentially
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 	 * nested waitqueues with custom wakeup handlers, then it should
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-	 * check eventfd_signal_allowed() before calling this function. If
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-	 * it returns false, the eventfd_signal() call should be deferred to a
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+	 * check eventfd_signal_count() before calling this function. If
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+	 * it returns true, the eventfd_signal() call should be deferred to a
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 	 * safe context.
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 	 */
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-	if (WARN_ON_ONCE(current->in_eventfd_signal))
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+	if (WARN_ON_ONCE(this_cpu_read(eventfd_wake_count)))
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 		return 0;
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 	spin_lock_irqsave(&ctx->wqh.lock, flags);
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-	current->in_eventfd_signal = 1;
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+	this_cpu_inc(eventfd_wake_count);
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 	if (ULLONG_MAX - ctx->count < n)
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 		n = ULLONG_MAX - ctx->count;
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 	ctx->count += n;
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 	if (waitqueue_active(&ctx->wqh))
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 		wake_up_locked_poll(&ctx->wqh, EPOLLIN | mask);
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-	current->in_eventfd_signal = 0;
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+	this_cpu_dec(eventfd_wake_count);
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 	spin_unlock_irqrestore(&ctx->wqh.lock, flags);
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 	return n;
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@@ -185,11 +187,14 @@
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 	return events;
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 }
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-static void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
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+void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
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 {
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-	*cnt = (ctx->flags & EFD_SEMAPHORE) ? 1 : ctx->count;
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+	lockdep_assert_held(&ctx->wqh.lock);
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+
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+	*cnt = ((ctx->flags & EFD_SEMAPHORE) && ctx->count) ? 1 : ctx->count;
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 	ctx->count -= *cnt;
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 }
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+EXPORT_SYMBOL_GPL(eventfd_ctx_do_read);
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 /**
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  * eventfd_ctx_remove_wait_queue - Read the current counter and removes wait queue.