From patchwork Sat Jun 20 22:11:10 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Davide Libenzi X-Patchwork-Id: 31624 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n5KMHbum007819 for ; Sat, 20 Jun 2009 22:17:37 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755635AbZFTWRY (ORCPT ); Sat, 20 Jun 2009 18:17:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754900AbZFTWRU (ORCPT ); Sat, 20 Jun 2009 18:17:20 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:52093 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754779AbZFTWRS (ORCPT ); Sat, 20 Jun 2009 18:17:18 -0400 X-AuthUser: davidel@xmailserver.org Received: from makko.or.mcafeemobile.com by x35.xmailserver.org with [XMail 1.26 ESMTP Server] id for from ; Sat, 20 Jun 2009 18:16:50 -0400 Date: Sat, 20 Jun 2009 15:11:10 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@makko.or.mcafeemobile.com To: Gregory Haskins cc: mst@redhat.com, kvm@vger.kernel.org, Linux Kernel Mailing List , avi@redhat.com, paulmck@linux.vnet.ibm.com, Ingo Molnar Subject: Re: [PATCH 3/3] eventfd: add internal reference counting to fix notifier race conditions In-Reply-To: Message-ID: References: <20090619183534.31118.30934.stgit@dev.haskins.net> <20090619185138.31118.14916.stgit@dev.haskins.net> <4A3C004B.8010706@novell.com> <4A3C07FF.3000406@novell.com> <4A3C44DA.7000503@novell.com> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Sat, 20 Jun 2009, Davide Libenzi wrote: > How about the one below? Maybe with an interface that can be undone w/out a file* :) - Davide --- fs/eventfd.c | 34 +++++++++++++++++++++++++++++++++- include/linux/eventfd.h | 8 ++++++++ 2 files changed, 41 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Index: linux-2.6.mod/fs/eventfd.c =================================================================== --- linux-2.6.mod.orig/fs/eventfd.c 2009-06-20 13:08:22.000000000 -0700 +++ linux-2.6.mod/fs/eventfd.c 2009-06-20 15:07:18.000000000 -0700 @@ -17,8 +17,10 @@ #include #include #include +#include struct eventfd_ctx { + struct kref kref; wait_queue_head_t wqh; /* * Every time that a write(2) is performed on an eventfd, the @@ -59,9 +61,19 @@ int eventfd_signal(struct file *file, in } EXPORT_SYMBOL_GPL(eventfd_signal); +static void eventfd_free(struct kref *kref) +{ + struct eventfd_ctx *ctx = container_of(kref, struct eventfd_ctx, kref); + + kfree(ctx); +} + static int eventfd_release(struct inode *inode, struct file *file) { - kfree(file->private_data); + struct eventfd_ctx *ctx = file->private_data; + + wake_up_poll(&ctx->wqh, POLLHUP); + kref_put(&ctx->kref, eventfd_free); return 0; } @@ -201,6 +213,25 @@ struct file *eventfd_fget(int fd) } EXPORT_SYMBOL_GPL(eventfd_fget); +struct eventfd_kref *eventfd_refget(struct file *file) +{ + struct eventfd_ctx *ctx = file->private_data; + + if (file->f_op != &eventfd_fops) + return ERR_PTR(-EINVAL); + kref_get(&ctx->kref); + return (struct eventfd_kref *) ctx; +} +EXPORT_SYMBOL_GPL(eventfd_refget); + +void eventfd_refput(struct eventfd_kref *ref) +{ + struct eventfd_ctx *ctx = (struct eventfd_ctx *) ref; + + kref_put(&ctx->kref, eventfd_free); +} +EXPORT_SYMBOL_GPL(eventfd_refput); + SYSCALL_DEFINE2(eventfd2, unsigned int, count, int, flags) { int fd; @@ -217,6 +248,7 @@ SYSCALL_DEFINE2(eventfd2, unsigned int, if (!ctx) return -ENOMEM; + kref_init(&ctx->kref); init_waitqueue_head(&ctx->wqh); ctx->count = count; ctx->flags = flags; Index: linux-2.6.mod/include/linux/eventfd.h =================================================================== --- linux-2.6.mod.orig/include/linux/eventfd.h 2009-06-20 13:08:22.000000000 -0700 +++ linux-2.6.mod/include/linux/eventfd.h 2009-06-20 15:06:03.000000000 -0700 @@ -8,6 +8,8 @@ #ifndef _LINUX_EVENTFD_H #define _LINUX_EVENTFD_H +struct eventfd_kref; + #ifdef CONFIG_EVENTFD /* For O_CLOEXEC and O_NONBLOCK */ @@ -29,12 +31,18 @@ struct file *eventfd_fget(int fd); int eventfd_signal(struct file *file, int n); +struct eventfd_kref *eventfd_refget(struct file *file); +void eventfd_refput(struct eventfd_kref *ref); #else /* CONFIG_EVENTFD */ #define eventfd_fget(fd) ERR_PTR(-ENOSYS) static inline int eventfd_signal(struct file *file, int n) { return 0; } +static inline struct eventfd_kref *eventfd_refget(struct file *file) +{ return ERR_PTR(-ENOSYS); } +static inline void eventfd_refput(struct eventfd_kref *ref) +{ } #endif /* CONFIG_EVENTFD */