On Tue, Jun 29, 2021 at 10:12 PM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
>
> FS_FAN_ERROR must be able to merge events even in the short window after
> they've been unqueued but prior to being read. Move the list_empty
This smells like trouble.
Breaking abstractions like this should be done for a very good reason
and I am not sure this is the case at hand.
More on this on merge_error_event patch.
Thanks,
Amir.
> check into the merge hooks, such that merge() is always invoked if
> existing.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
> ---
> fs/notify/fanotify/fanotify.c | 3 ++-
> fs/notify/inotify/inotify_fsnotify.c | 3 +++
> fs/notify/notification.c | 2 +-
> 3 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index aba06b84da91..769703ef2b9a 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -168,7 +168,8 @@ static int fanotify_merge(struct fsnotify_group *group,
> * the event structure we have created in fanotify_handle_event() is the
> * one we should check for permission response.
> */
> - if (fanotify_is_perm_event(new->mask))
> + if (list_empty(&group->notification_list) ||
> + fanotify_is_perm_event(new->mask))
> return 0;
>
> hlist_for_each_entry(old, hlist, merge_list) {
> diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
> index a003a64ff8ee..2f357b4933c2 100644
> --- a/fs/notify/inotify/inotify_fsnotify.c
> +++ b/fs/notify/inotify/inotify_fsnotify.c
> @@ -52,6 +52,9 @@ static int inotify_merge(struct fsnotify_group *group,
> struct list_head *list = &group->notification_list;
> struct fsnotify_event *last_event;
>
> + if (list_empty(list))
> + return 0;
> +
> last_event = list_entry(list->prev, struct fsnotify_event, list);
> return event_compare(last_event, event);
> }
> diff --git a/fs/notify/notification.c b/fs/notify/notification.c
> index 0d9ba592d725..1d06e0728a24 100644
> --- a/fs/notify/notification.c
> +++ b/fs/notify/notification.c
> @@ -111,7 +111,7 @@ int fsnotify_add_event(struct fsnotify_group *group,
> goto queue;
> }
>
> - if (!list_empty(list) && merge) {
> + if (merge) {
> ret = merge(group, event);
> if (ret) {
> spin_unlock(&group->notification_lock);
> --
> 2.32.0
>
