@@ -109,6 +109,9 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 	struct timestamp_event_queue *queue;
 	char debugfsname[32];
 
+	if (mutex_lock_interruptible(&ptp->tsevq_mux)) 
+		return -ERESTARTSYS;
+
 	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
 	if (!queue)
 		return -EINVAL;

@@ -132,15 +135,20 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 	debugfs_create_u32_array("mask", 0444, queue->debugfs_instance,
 				 &queue->dfs_bitmap);
 
+	mutex_unlock(&ptp->tsevq_mux);
 	return 0;
 }
 
 int ptp_release(struct posix_clock_context *pccontext)
 {
 	struct timestamp_event_queue *queue = pccontext->private_clkdata;
+	struct ptp_clock *ptp =
+		container_of(pccontext->clk, struct ptp_clock, clock);
 	unsigned long flags;
 
 	if (queue) {
+		if (mutex_lock_interruptible(&ptp->tsevq_mux)) 
+			return -ERESTARTSYS;
 		debugfs_remove(queue->debugfs_instance);
 		pccontext->private_clkdata = NULL;
 		spin_lock_irqsave(&queue->lock, flags);

@@ -148,6 +156,7 @@ int ptp_release(struct posix_clock_context *pccontext)
 		spin_unlock_irqrestore(&queue->lock, flags);
 		bitmap_free(queue->mask);
 		kfree(queue);
+		mutex_unlock(&ptp->tsevq_mux);
 	}
 	return 0;
 }

@@ -543,6 +552,8 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
 		cnt = EXTTS_BUFSIZE;
 
 	cnt = cnt / sizeof(struct ptp_extts_event);
+	if (mutex_lock_interruptible(&ptp->tsevq_mux)) 
+		return -ERESTARTSYS;
 
 	if (wait_event_interruptible(ptp->tsev_wq,
 				     ptp->defunct || queue_cnt(queue))) {

@@ -585,7 +596,6 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
 free_event:
 	kfree(event);
 exit:
-	if (result < 0)
-		ptp_release(pccontext);
+	mutex_unlock(&ptp->tsevq_mux);
 	return result;
 }

@@ -176,6 +176,7 @@ static void ptp_clock_release(struct device *dev)
 
 	ptp_cleanup_pin_groups(ptp);
 	kfree(ptp->vclock_index);
+	mutex_destroy(&ptp->tsevq_mux);
 	mutex_destroy(&ptp->pincfg_mux);
 	mutex_destroy(&ptp->n_vclocks_mux);
 	/* Delete first entry */

@@ -247,6 +248,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	if (!queue)
 		goto no_memory_queue;
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
+	mutex_init(&ptp->tsevq_mux);
 	queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
 	if (!queue->mask)
 		goto no_memory_bitmap;

@@ -356,6 +358,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	if (ptp->kworker)
 		kthread_destroy_worker(ptp->kworker);
 kworker_err:
+	mutex_destroy(&ptp->tsevq_mux);
 	mutex_destroy(&ptp->pincfg_mux);
 	mutex_destroy(&ptp->n_vclocks_mux);
 	bitmap_free(queue->mask);

@@ -44,6 +44,7 @@ struct ptp_clock {
 	struct pps_device *pps_source;
 	long dialed_frequency; /* remembers the frequency adjustment */
 	struct list_head tsevqs; /* timestamp fifo list */
+	struct mutex tsevq_mux; /* one process at a time reading the fifo */
 	struct mutex pincfg_mux; /* protect concurrent info->pin_config access */
 	wait_queue_head_t tsev_wq;
 	int defunct; /* tells readers to go away when clock is being removed */