在 2021/8/31 下午6:36, Xie Yongji 写道:
Export eventfd_wake_count so that some modules can use
the eventfd_signal_count() to check whether the
eventfd_signal() call should be deferred to a safe context.
Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
And this matches the comment inside eventfd_signal():
/*
* Deadlock or stack overflow issues can happen if we recurse here
* through waitqueue wakeup handlers. If the caller users
potentially
* nested waitqueues with custom wakeup handlers, then it should
* check eventfd_signal_count() before calling this function. If
* it returns true, the eventfd_signal() call should be
deferred to a
* safe context.
*/
So:
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
---
fs/eventfd.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/eventfd.c b/fs/eventfd.c
index e265b6dd4f34..1b3130b8d6c1 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -26,6 +26,7 @@
#include <linux/uio.h>
DEFINE_PER_CPU(int, eventfd_wake_count);
+EXPORT_PER_CPU_SYMBOL_GPL(eventfd_wake_count);
static DEFINE_IDA(eventfd_ida);
