efi_loader: implement event queue

Up to now we have only been using a flag queued for events. But this does
not satisfy the requirements of the UEFI spec. Events must be notified in
the sequence of decreasing TPL level and within a TPL level in the sequence
of signaling.

Implement a queue for signaled events.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 8a3f8fe..f0e1313 100644 (file)
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -256,6 +256,7 @@ struct efi_loaded_image_obj {
  * struct efi_event
  *
  * @link:              Link to list of all events
+ * @queue_link:                Link to the list of queued events
  * @type:              Type of event, see efi_create_event
  * @notify_tpl:                Task priority level of notifications
  * @nofify_function:   Function to call when the event is triggered
@@ -264,11 +265,11 @@ struct efi_loaded_image_obj {
  * @trigger_time:      Period of the timer
  * @trigger_next:      Next time to trigger the timer
  * @trigger_type:      Type of timer, see efi_set_timer
- * @is_queued:         The notification function is queued
  * @is_signaled:       The event occurred. The event is in the signaled state.
  */
 struct efi_event {
        struct list_head link;
+       struct list_head queue_link;
        uint32_t type;
        efi_uintn_t notify_tpl;
        void (EFIAPI *notify_function)(struct efi_event *event, void *context);
@@ -277,7 +278,6 @@ struct efi_event {
        u64 trigger_next;
        u64 trigger_time;
        enum efi_timer_delay trigger_type;
-       bool is_queued;
        bool is_signaled;
 };
 

diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index c146b47..fa01bbd 100644 (file)
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -27,6 +27,9 @@ LIST_HEAD(efi_obj_list);
 /* List of all events */
 LIST_HEAD(efi_events);
 
+/* List of queued events */
+LIST_HEAD(efi_event_queue);
+
 /* Flag to disable timer activity in ExitBootServices() */
 static bool timers_enabled = true;
 
@@ -164,31 +167,75 @@ const char *__efi_nesting_dec(void)
 }
 
 /**
+ * efi_event_is_queued() - check if an event is queued
+ *
+ * @event:     event
+ * Return:     true if event is queued
+ */
+static bool efi_event_is_queued(struct efi_event *event)
+{
+       return !!event->queue_link.next;
+}
+
+/**
+ * efi_process_event_queue() - process event queue
+ */
+static void efi_process_event_queue(void)
+{
+       while (!list_empty(&efi_event_queue)) {
+               struct efi_event *event;
+               efi_uintn_t old_tpl;
+
+               event = list_first_entry(&efi_event_queue, struct efi_event,
+                                        queue_link);
+               if (efi_tpl >= event->notify_tpl)
+                       return;
+               list_del(&event->queue_link);
+               event->queue_link.next = NULL;
+               event->queue_link.prev = NULL;
+               /* Events must be executed at the event's TPL */
+               old_tpl = efi_tpl;
+               efi_tpl = event->notify_tpl;
+               EFI_CALL_VOID(event->notify_function(event,
+                                                    event->notify_context));
+               efi_tpl = old_tpl;
+               if (event->type == EVT_NOTIFY_SIGNAL)
+                       event->is_signaled = 0;
+       }
+}
+
+/**
  * efi_queue_event() - queue an EFI event
  * @event:     event to signal
  *
  * This function queues the notification function of the event for future
  * execution.
  *
- * The notification function is called if the task priority level of the event
- * is higher than the current task priority level.
- *
- * For the SignalEvent service see efi_signal_event_ext.
- *
  */
 static void efi_queue_event(struct efi_event *event)
 {
-       if (event->notify_function) {
-               event->is_queued = true;
-               /* Check TPL */
-               if (efi_tpl >= event->notify_tpl)
-                       return;
-               event->is_queued = false;
-               EFI_CALL_VOID(event->notify_function(event,
-                                                    event->notify_context));
-       } else {
-               event->is_queued = false;
+       struct efi_event *item = NULL;
+
+       if (!event->notify_function)
+               return;
+
+       if (!efi_event_is_queued(event)) {
+               /*
+                * Events must be notified in order of decreasing task priority
+                * level. Insert the new event accordingly.
+                */
+               list_for_each_entry(item, &efi_event_queue, queue_link) {
+                       if (item->notify_tpl < event->notify_tpl) {
+                               list_add_tail(&event->queue_link,
+                                             &item->queue_link);
+                               event = NULL;
+                               break;
+                       }
+               }
+               if (event)
+                       list_add_tail(&event->queue_link, &efi_event_queue);
        }
+       efi_process_event_queue();
 }
 
 /**
@@ -237,20 +284,15 @@ void efi_signal_event(struct efi_event *event)
                        if (evt->is_signaled)
                                continue;
                        evt->is_signaled = true;
-                       if (evt->type & EVT_NOTIFY_SIGNAL &&
-                           evt->notify_function)
-                               evt->is_queued = true;
                }
                list_for_each_entry(evt, &efi_events, link) {
                        if (!evt->group || guidcmp(evt->group, event->group))
                                continue;
-                       if (evt->is_queued)
-                               efi_queue_event(evt);
+                       efi_queue_event(evt);
                }
        } else {
                event->is_signaled = true;
-               if (event->type & EVT_NOTIFY_SIGNAL)
-                       efi_queue_event(event);
+               efi_queue_event(event);
        }
 }
 
@@ -640,8 +682,6 @@ efi_status_t efi_create_event(uint32_t type, efi_uintn_t notify_tpl,
        evt->group = group;
        /* Disable timers on boot up */
        evt->trigger_next = -1ULL;
-       evt->is_queued = false;
-       evt->is_signaled = false;
        list_add_tail(&evt->link, &efi_events);
        *event = evt;
        return EFI_SUCCESS;
@@ -736,8 +776,6 @@ void efi_timer_check(void)
        u64 now = timer_get_us();
 
        list_for_each_entry(evt, &efi_events, link) {
-               if (evt->is_queued)
-                       efi_queue_event(evt);
                if (!timers_enabled)
                        continue;
                if (!(evt->type & EVT_TIMER) || now < evt->trigger_next)
@@ -755,6 +793,7 @@ void efi_timer_check(void)
                evt->is_signaled = false;
                efi_signal_event(evt);
        }
+       efi_process_event_queue();
        WATCHDOG_RESET();
 }
 
@@ -938,6 +977,9 @@ static efi_status_t EFIAPI efi_close_event(struct efi_event *event)
                        free(item);
                }
        }
+       /* Remove event from queue */
+       if (efi_event_is_queued(event))
+               list_del(&event->queue_link);
 
        list_del(&event->link);
        free(event);