From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752539AbaBXJbS (ORCPT ); Mon, 24 Feb 2014 04:31:18 -0500 Received: from cantor2.suse.de ([195.135.220.15]:52777 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752476AbaBXJbP (ORCPT ); Mon, 24 Feb 2014 04:31:15 -0500 From: Jan Kara To: linux-fsdevel@vger.kernel.org Cc: poma , Richard Weinberger , LKML , eparis@parisplace.org, Jan Kara Subject: [PATCH 2/3] fanotify: Handle overflow in case of permission events Date: Mon, 24 Feb 2014 10:31:06 +0100 Message-Id: <1393234267-22937-3-git-send-email-jack@suse.cz> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1393234267-22937-1-git-send-email-jack@suse.cz> References: <1393234267-22937-1-git-send-email-jack@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the event queue overflows when we are handling permission event, we will never get response from userspace. So we must avoid waiting for it. Change fsnotify_add_notify_event() to return whether overflow has happened so that we can detect it in fanotify_handle_event() and act accordingly. Signed-off-by: Jan Kara --- fs/notify/fanotify/fanotify.c | 6 ++++-- fs/notify/notification.c | 14 ++++++++++---- 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 0e792f5e3147..7564a070e6e8 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -192,10 +192,12 @@ static int fanotify_handle_event(struct fsnotify_group *group, ret = fsnotify_add_notify_event(group, fsn_event, fanotify_merge); if (ret) { - BUG_ON(mask & FAN_ALL_PERM_EVENTS); + /* Permission events shouldn't be merged */ + BUG_ON(ret == 1 && mask & FAN_ALL_PERM_EVENTS); /* Our event wasn't used in the end. Free it. */ fsnotify_destroy_event(group, fsn_event); - ret = 0; + + return 0; } #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS diff --git a/fs/notify/notification.c b/fs/notify/notification.c index 6bec2f4918f9..6a4ba17c0395 100644 --- a/fs/notify/notification.c +++ b/fs/notify/notification.c @@ -80,7 +80,8 @@ void fsnotify_destroy_event(struct fsnotify_group *group, /* * Add an event to the group notification queue. The group can later pull this * event off the queue to deal with. The function returns 0 if the event was - * added to the queue, 1 if the event was merged with some other queued event. + * added to the queue, 1 if the event was merged with some other queued event, + * 2 if the queue of events has overflown. */ int fsnotify_add_notify_event(struct fsnotify_group *group, struct fsnotify_event *event, @@ -95,10 +96,14 @@ int fsnotify_add_notify_event(struct fsnotify_group *group, mutex_lock(&group->notification_mutex); if (group->q_len >= group->max_events) { + ret = 2; /* Queue overflow event only if it isn't already queued */ - if (list_empty(&group->overflow_event.list)) - event = &group->overflow_event; - ret = 1; + if (!list_empty(&group->overflow_event.list)) { + mutex_unlock(&group->notification_mutex); + return ret; + } + event = &group->overflow_event; + goto queue; } if (!list_empty(list) && merge) { @@ -109,6 +114,7 @@ int fsnotify_add_notify_event(struct fsnotify_group *group, } } +queue: group->q_len++; list_add_tail(&event->list, list); mutex_unlock(&group->notification_mutex); -- 1.8.1.4