eventfd currently emits a POLLHUP wakeup on f_ops->release() to generate a
"release" callback. This lets eventfd clients know if the eventfd is about
to go away and is very useful particularly for in-kernel clients. However,
as it stands today it is not possible to use this feature of eventfd in a
race-free way. This patch changes the POLLHUP code to use the locked variant
to rectify this problem.
Signed-off-by: Gregory Haskins <ghaskins@xxxxxxxxxx>
CC: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
---
fs/eventfd.c | 7 +------
1 files changed, 1 insertions(+), 6 deletions(-)
diff --git a/fs/eventfd.c b/fs/eventfd.c
index d9849a1..31d12de 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -105,12 +105,7 @@ static int eventfd_release(struct inode *inode, struct file *file)
{
struct eventfd_ctx *ctx = file->private_data;
- /*
- * No need to hold the lock here, since we are on the file cleanup
- * path and the ones still attached to the wait queue will be
- * serialized by wake_up_locked_poll().
- */
- wake_up_locked_poll(&ctx->wqh, POLLHUP);
+ wake_up_poll(&ctx->wqh, POLLHUP);
eventfd_ctx_put(ctx);
return 0;
}
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