From: Davide Libenzi <[email protected]> And give them a change to unregister from the wait queue.
This is turn allows eventfd users to use the eventfd file* w/out holding a live reference to it. After the eventfd user callbacks returns, any usage of the eventfd file* should be dropped. The eventfd user callback can acquire sleepy locks since it is invoked lockless. This is a feature, needed by KVM to avoid an awkward workaround when using eventfd. Signed-off-by: Davide Libenzi <[email protected]> Tested-by: Gregory Haskins <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Gregory Haskins <[email protected]> Signed-off-by: Avi Kivity <[email protected]> diff --git a/fs/eventfd.c b/fs/eventfd.c index 3f0e197..72f5f8d 100644 --- a/fs/eventfd.c +++ b/fs/eventfd.c @@ -61,7 +61,15 @@ EXPORT_SYMBOL_GPL(eventfd_signal); static int eventfd_release(struct inode *inode, struct file *file) { - kfree(file->private_data); + 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); + kfree(ctx); return 0; } -- To unsubscribe from this list: send the line "unsubscribe kvm-commits" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
