From patchwork Mon Jun 1 21:50:43 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 27301 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 n51LtDGt026970 for ; Mon, 1 Jun 2009 21:55:13 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756747AbZFAVwW (ORCPT ); Mon, 1 Jun 2009 17:52:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756595AbZFAVwR (ORCPT ); Mon, 1 Jun 2009 17:52:17 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:43437 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754687AbZFAVvB (ORCPT ); Mon, 1 Jun 2009 17:51:01 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out01.mta.xmission.com with esmtp (Exim 4.62) (envelope-from ) id 1MBFPb-0007xs-2p; Mon, 01 Jun 2009 15:51:19 -0600 Received: from [76.21.114.89] (helo=fess.ebiederm.org) by in02.mta.xmission.com with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.69) (envelope-from ) id 1MBFPK-00048X-BG; Mon, 01 Jun 2009 15:51:03 -0600 Received: from fess.ebiederm.org (localhost [127.0.0.1]) by fess.ebiederm.org (8.14.3/8.14.3/Debian-4) with ESMTP id n51Lox7A017133; Mon, 1 Jun 2009 14:50:59 -0700 Received: (from eric@localhost) by fess.ebiederm.org (8.14.3/8.14.3/Submit) id n51LoxUd017132; Mon, 1 Jun 2009 14:50:59 -0700 From: "Eric W. Biederman" To: Al Viro Cc: , , , , Hugh Dickins , Tejun Heo , Alexey Dobriyan , Linus Torvalds , Alan Cox , Greg Kroah-Hartman , Nick Piggin , Andrew Morton , Christoph Hellwig , "Eric W. Biederman" , "Eric W. Biederman" Date: Mon, 1 Jun 2009 14:50:43 -0700 Message-Id: <1243893048-17031-18-git-send-email-ebiederm@xmission.com> X-Mailer: git-send-email 1.6.3.1.54.g99dd.dirty In-Reply-To: References: X-XM-SPF: eid=; ; ; mid=; ; ; hst=in02.mta.xmission.com; ; ; ip=76.21.114.89; ; ; frm=ebiederm@xmission.com; ; ; spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Rcpt-To: viro@ZenIV.linux.org.uk, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, hugh@veritas.com, tj@kernel.org, adobriyan@gmail.com, torvalds@linux-foundation.org, alan@lxorguk.ukuu.org.uk, gregkh@suse.de, npiggin@suse.de, akpm@linux-foundation.org, hch@infradead.org, ebiederm@maxwell.aristanetworks.com, ebiederm@aristanetworks.com X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-DCC: XMission; sa04 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on sa04.xmission.com X-Spam-Level: X-Spam-Status: No, score=-2.5 required=8.0 tests=ALL_TRUSTED,BAYES_00, DCC_CHECK_NEGATIVE, T_TM2_M_HEADER_IN_MSG, T_TooManySym_01, UNTRUSTED_Relay, XMNoVowels,XM_SPF_Neutral autolearn=disabled version=3.2.5 X-Spam-Combo: ;Al Viro X-Spam-Relay-Country: X-Spam-Report: * -1.8 ALL_TRUSTED Passed through trusted hosts only via SMTP * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -2.6 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa04 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject * 0.0 XM_SPF_Neutral SPF-Neutral * 0.4 UNTRUSTED_Relay Comes from a non-trusted relay Subject: [PATCH 18/23] vfs: Teach epoll to use file_hotplug_lock X-SA-Exim-Version: 4.2.1 (built Thu, 25 Oct 2007 00:26:12 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Eric W. Biederman Signed-off-by: Eric W. Biederman --- fs/eventpoll.c | 39 ++++++++++++++++++++++++++++++++------- 1 files changed, 32 insertions(+), 7 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index a89f370..eabb167 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -627,8 +627,13 @@ static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, struct epitem *epi, *tmp; list_for_each_entry_safe(epi, tmp, head, rdllink) { - if (epi->ffd.file->f_op->poll(epi->ffd.file, NULL) & - epi->event.events) + int events = DEAD_POLLMASK; + + if (file_hotplug_read_trylock(epi->ffd.file)) { + events = epi->ffd.file->f_op->poll(epi->ffd.file, NULL); + file_hotplug_read_unlock(epi->ffd.file); + } + if (events & epi->event.events) return POLLIN | POLLRDNORM; else { /* @@ -1060,8 +1065,12 @@ static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head, list_del_init(&epi->rdllink); - revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL) & - epi->event.events; + revents = DEAD_POLLMASK; + if (file_hotplug_read_trylock(epi->ffd.file)) { + revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL); + file_hotplug_read_unlock(epi->ffd.file); + } + revents &= epi->event.events; /* * If the event mask intersect the caller-requested one, @@ -1248,10 +1257,17 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, if (!tfile) goto error_fput; + error = -EIO; + if (!file_hotplug_read_trylock(file)) + goto error_tgt_fput; + + if (!file_hotplug_read_trylock(tfile)) + goto error_file_unlock; + /* The target file descriptor must support poll */ error = -EPERM; if (!tfile->f_op || !tfile->f_op->poll) - goto error_tgt_fput; + goto error_tgt_unlock; /* * We have to check that the file structure underneath the file descriptor @@ -1260,7 +1276,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, */ error = -EINVAL; if (file == tfile || !is_file_epoll(file)) - goto error_tgt_fput; + goto error_tgt_unlock; /* * At this point it is safe to assume that the "private_data" contains @@ -1302,6 +1318,10 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, } mutex_unlock(&ep->mtx); +error_tgt_unlock: + file_hotplug_read_unlock(tfile); +error_file_unlock: + file_hotplug_read_unlock(file); error_tgt_fput: fput(tfile); error_fput: @@ -1338,13 +1358,16 @@ SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events, if (!file) goto error_return; + error = -EIO; + if (!file_hotplug_read_trylock(file)) + goto error_fput; /* * We have to check that the file structure underneath the fd * the user passed to us _is_ an eventpoll file. */ error = -EINVAL; if (!is_file_epoll(file)) - goto error_fput; + goto error_unlock; /* * At this point it is safe to assume that the "private_data" contains @@ -1355,6 +1378,8 @@ SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events, /* Time to fish for events ... */ error = ep_poll(ep, events, maxevents, timeout); +error_unlock: + file_hotplug_read_unlock(file); error_fput: fput(file); error_return: