From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory Haskins Subject: [KVM PATCH v9 2/5] eventfd: use locked POLLHUP Date: Thu, 02 Jul 2009 11:38:06 -0400 Message-ID: <20090702153806.20186.76377.stgit@dev.haskins.net> References: <20090702153454.20186.99191.stgit@dev.haskins.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, mst@redhat.com, avi@redhat.com, davidel@xmailserver.org To: kvm@vger.kernel.org Return-path: Received: from victor.provo.novell.com ([137.65.250.26]:36919 "EHLO victor.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752712AbZGBPiJ (ORCPT ); Thu, 2 Jul 2009 11:38:09 -0400 In-Reply-To: <20090702153454.20186.99191.stgit@dev.haskins.net> Sender: kvm-owner@vger.kernel.org List-ID: 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 CC: Davide Libenzi --- 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; }