Current code has an assumtion that fsnotify_notify_queue_is_empty() is
called to verify that queue is not empty before trying to peek or remove
an event from queue.
Remove this assumption by moving the fsnotify_notify_queue_is_empty()
into the functions, allow them to return NULL value and check return
value by all callers.
This is a prep patch for multi event queues.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fanotify/fanotify_user.c | 26 +++++++++++-------
fs/notify/inotify/inotify_user.c | 5 ++--
fs/notify/notification.c | 42 ++++++++++++++----------------
include/linux/fsnotify_backend.h | 8 +++++-
4 files changed, 44 insertions(+), 37 deletions(-)
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 9e0c1afac8bd..16162207e886 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -100,24 +100,30 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group,
{
size_t event_size = FAN_EVENT_METADATA_LEN;
struct fanotify_event *event = NULL;
+ struct fsnotify_event *fsn_event;
unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
spin_lock(&group->notification_lock);
- if (fsnotify_notify_queue_is_empty(group))
+ fsn_event = fsnotify_peek_first_event(group);
+ if (!fsn_event)
goto out;
- if (fid_mode) {
- event_size += fanotify_event_info_len(fid_mode,
- FANOTIFY_E(fsnotify_peek_first_event(group)));
- }
+ event = FANOTIFY_E(fsn_event);
+ if (fid_mode)
+ event_size += fanotify_event_info_len(fid_mode, event);
if (event_size > count) {
event = ERR_PTR(-EINVAL);
goto out;
}
- event = FANOTIFY_E(fsnotify_remove_first_event(group));
+
+ /*
+ * Held the notification_lock the whole time, so this is the
+ * same event we peeked above.
+ */
+ fsnotify_remove_first_event(group);
if (fanotify_is_perm_event(event->mask))
FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED;
out:
@@ -573,6 +579,7 @@ static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t
static int fanotify_release(struct inode *ignored, struct file *file)
{
struct fsnotify_group *group = file->private_data;
+ struct fsnotify_event *fsn_event;
/*
* Stop new events from arriving in the notification queue. since
@@ -601,13 +608,12 @@ static int fanotify_release(struct inode *ignored, struct file *file)
* dequeue them and set the response. They will be freed once the
* response is consumed and fanotify_get_response() returns.
*/
- while (!fsnotify_notify_queue_is_empty(group)) {
- struct fanotify_event *event;
+ while ((fsn_event = fsnotify_remove_first_event(group))) {
+ struct fanotify_event *event = FANOTIFY_E(fsn_event);
- event = FANOTIFY_E(fsnotify_remove_first_event(group));
if (!(event->mask & FANOTIFY_PERM_EVENTS)) {
spin_unlock(&group->notification_lock);
- fsnotify_destroy_event(group, &event->fse);
+ fsnotify_destroy_event(group, fsn_event);
} else {
finish_permission_event(group, FANOTIFY_PERM(event),
FAN_ALLOW);
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index c71be4fb7dc5..a6c95bd64618 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -146,10 +146,9 @@ static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
size_t event_size = sizeof(struct inotify_event);
struct fsnotify_event *event;
- if (fsnotify_notify_queue_is_empty(group))
- return NULL;
-
event = fsnotify_peek_first_event(group);
+ if (!event)
+ return NULL;
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
diff --git a/fs/notify/notification.c b/fs/notify/notification.c
index 75d79d6d3ef0..001cfe7d2e4e 100644
--- a/fs/notify/notification.c
+++ b/fs/notify/notification.c
@@ -47,13 +47,6 @@ u32 fsnotify_get_cookie(void)
}
EXPORT_SYMBOL_GPL(fsnotify_get_cookie);
-/* return true if the notify queue is empty, false otherwise */
-bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group)
-{
- assert_spin_locked(&group->notification_lock);
- return list_empty(&group->notification_list) ? true : false;
-}
-
void fsnotify_destroy_event(struct fsnotify_group *group,
struct fsnotify_event *event)
{
@@ -141,33 +134,36 @@ void fsnotify_remove_queued_event(struct fsnotify_group *group,
}
/*
- * Remove and return the first event from the notification list. It is the
- * responsibility of the caller to destroy the obtained event
+ * Return the first event on the notification list without removing it.
+ * Returns NULL if the list is empty.
*/
-struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group)
+struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group)
{
- struct fsnotify_event *event;
-
assert_spin_locked(&group->notification_lock);
- pr_debug("%s: group=%p\n", __func__, group);
+ if (fsnotify_notify_queue_is_empty(group))
+ return NULL;
- event = list_first_entry(&group->notification_list,
- struct fsnotify_event, list);
- fsnotify_remove_queued_event(group, event);
- return event;
+ return list_first_entry(&group->notification_list,
+ struct fsnotify_event, list);
}
/*
- * This will not remove the event, that must be done with
- * fsnotify_remove_first_event()
+ * Remove and return the first event from the notification list. It is the
+ * responsibility of the caller to destroy the obtained event
*/
-struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group)
+struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group)
{
- assert_spin_locked(&group->notification_lock);
+ struct fsnotify_event *event = fsnotify_peek_first_event(group);
- return list_first_entry(&group->notification_list,
- struct fsnotify_event, list);
+ if (!event)
+ return NULL;
+
+ pr_debug("%s: group=%p event=%p\n", __func__, group, event);
+
+ fsnotify_remove_queued_event(group, event);
+
+ return event;
}
/*
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index e5409b83e731..7eb979bfc141 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -495,7 +495,13 @@ static inline void fsnotify_queue_overflow(struct fsnotify_group *group)
fsnotify_add_event(group, group->overflow_event, NULL);
}
-/* true if the group notification queue is empty */
+static inline bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group)
+{
+ assert_spin_locked(&group->notification_lock);
+
+ return list_empty(&group->notification_list);
+}
+
extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
/* return, but do not dequeue the first event on the notification queue */
extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group);
--
2.30.0
