From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Eric W. Biederman" Subject: [PATCH 18/23] vfs: Teach epoll to use file_hotplug_lock Date: Mon, 1 Jun 2009 14:50:43 -0700 Message-ID: <1243893048-17031-18-git-send-email-ebiederm@xmission.com> References: 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" To: Al Viro Return-path: 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 In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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: -- 1.6.3.1.54.g99dd.dirty