SYSLINK:ipc:notify drv read fix

This patch fixes the bug in notify drv read where
the read thread wouldn't get blocked if the event
list is empty. This bug resulted in board freeze
in Zebu enviornment because the read thread was
blockign all other threads from getting scheduled.

Signed-off-by: Hari Kanigeri<h-kanigeri2@ti.com>

drivers/dsp/syslink/omap_notify/drv_notify.c

@@ -230,7 +230,6 @@ static int notify_drv_read(struct file *filp, char *dst, size_t size,
 	u32 i;
 	struct list_head *elem;
 	struct notify_drv_event_packet t_buf;
-
 	if (WARN_ON(notifydrv_state.is_setup == false)) {
 		ret_val = -EFAULT;
 		goto func_end;
@@ -252,34 +251,32 @@ static int notify_drv_read(struct file *filp, char *dst, size_t size,
 		ret_val = -EFAULT;
 		goto func_end;
 	}
-	if (list_empty(&(notifydrv_state.event_state[i].buf_list)) == false) {
-		/* Wait for the event */
-		ret_val = down_interruptible(
-			notifydrv_state.event_state[i].semhandle);
-		if (ret_val < 0) {
-			ret_val = -ERESTARTSYS;
-			goto func_end;
-		}
-		WARN_ON(mutex_lock_interruptible(notifydrv_state.gatehandle));
-		elem = ((struct list_head *)&(notifydrv_state.event_state[i]. \
-							buf_list))->next;
-		u_buf = container_of(elem, struct notify_drv_event_packet,
-				    element);
-		list_del(elem);
-		mutex_unlock(notifydrv_state.gatehandle);
-		if (u_buf == NULL) {
-			ret_val = -EFAULT;
-			goto func_end;
-		}
-		ret_val = copy_to_user((void *)dst, u_buf,
-			sizeof(struct notify_drv_event_packet));
-		kfree(u_buf);
-
-		if (WARN_ON(ret_val != 0))
-			ret_val = -EFAULT;
-		if (u_buf->is_exit == true)
-			up(notifydrv_state.event_state[i].tersemhandle);
+	/* Wait for the event */
+	ret_val = down_interruptible(
+		notifydrv_state.event_state[i].semhandle);
+	if (ret_val < 0) {
+		ret_val = -ERESTARTSYS;
+		goto func_end;
 	}
+	WARN_ON(mutex_lock_interruptible(notifydrv_state.gatehandle));
+	elem = ((struct list_head *)&(notifydrv_state.event_state[i]. \
+						buf_list))->next;
+	u_buf = container_of(elem, struct notify_drv_event_packet,
+			    element);
+	list_del(elem);
+	mutex_unlock(notifydrv_state.gatehandle);
+	if (u_buf == NULL) {
+		ret_val = -EFAULT;
+		goto func_end;
+	}
+	ret_val = copy_to_user((void *)dst, u_buf,
+		sizeof(struct notify_drv_event_packet));
+	kfree(u_buf);
+	if (WARN_ON(ret_val != 0))
+		ret_val = -EFAULT;
+	if (u_buf->is_exit == true)
+		up(notifydrv_state.event_state[i].tersemhandle);
+
 func_end:
 	return ret_val ;
 }