| Message ID | 1381160190-13686-1-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index a506360..0c2f912 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -18,6 +18,12 @@ static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new) old->tgid == new->tgid) { switch (old->data_type) { case (FSNOTIFY_EVENT_PATH): +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + /* dont merge two permission events */ + if ((old->mask & FAN_ALL_PERM_EVENTS) && + (new->mask & FAN_ALL_PERM_EVENTS)) + return false; +#endif if ((old->path.mnt == new->path.mnt) && (old->path.dentry == new->path.dentry)) return true;
This is a note to let you know that I have just added a patch titled fanotify: dont merge permission events to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From c71a3a1ee282b68e2566f4d3bd2c70485538c142 Mon Sep 17 00:00:00 2001 From: Lino Sanfilippo <LinoSanfilippo@gmx.de> Date: Fri, 23 Mar 2012 02:42:23 +0100 Subject: [PATCH] fanotify: dont merge permission events commit 03a1cec1f17ac1a6041996b3e40f96b5a2f90e1b upstream. Boyd Yang reported a problem for the case that multiple threads of the same thread group are waiting for a reponse for a permission event. In this case it is possible that some of the threads are never woken up, even if the response for the event has been received (see http://marc.info/?l=linux-kernel&m=131822913806350&w=2). The reason is that we are currently merging permission events if they belong to the same thread group. But we are not prepared to wake up more than one waiter for each event. We do wait_event(group->fanotify_data.access_waitq, event->response || atomic_read(&group->fanotify_data.bypass_perm)); and after that event->response = 0; which is the reason that even if we woke up all waiters for the same event some of them may see event->response being already set 0 again, then go back to sleep and block forever. With this patch we avoid that more than one thread is waiting for a response by not merging permission events for the same thread group any more. Reported-by: Boyd Yang <boyd.yang@gmail.com> Signed-off-by: Lino Sanfilippo <LinoSanfilipp@gmx.de> Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- fs/notify/fanotify/fanotify.c | 6 ++++++ 1 file changed, 6 insertions(+) -- 1.8.3.2