drm/amdkfd: SMI report dropped event count

Add new SMI event to report the dropped event count.

When the event kfifo is full, drop count is not zero, or no enough space
left to store the event message, increase drop count.

After reading event out from kfifo, if event was dropped, drop_count is
not zero, generate a dropped event record and reset drop count to zero.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: James Zhu <James.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 23 insertions, 4 deletions

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
index 9b8169761ec5..c8d67d62ca3f 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
@@ -42,6 +42,7 @@ struct kfd_smi_client {
 	struct rcu_head rcu;
 	pid_t pid;
 	bool suser;
+	u32 drop_count;
 };
 
 #define KFD_MAX_KFIFO_SIZE	8192
@@ -103,12 +104,28 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
 	}
 	to_copy = min(size, to_copy);
 	ret = kfifo_out(&client->fifo, buf, to_copy);
-	spin_unlock(&client->lock);
 	if (ret <= 0) {
+		spin_unlock(&client->lock);
 		ret = -EAGAIN;
 		goto ret_err;
 	}
 
+	if (client->drop_count) {
+		char msg[KFD_SMI_EVENT_MSG_SIZE];
+		int len;
+
+		len = snprintf(msg, sizeof(msg), "%x ", KFD_SMI_EVENT_DROPPED_EVENT);
+		len += snprintf(msg + len, sizeof(msg) - len,
+				KFD_EVENT_FMT_DROPPED_EVENT(ktime_get_boottime_ns(),
+				client->pid, client->drop_count));
+		if (kfifo_avail(&client->fifo) >= len) {
+			kfifo_in(&client->fifo, msg, len);
+			client->drop_count = 0;
+		}
+	}
+
+	spin_unlock(&client->lock);
+
 	ret = copy_to_user(user, buf, to_copy);
 	if (ret) {
 		ret = -EFAULT;
@@ -182,13 +199,15 @@ static void add_event_to_kfifo(pid_t pid, struct kfd_node *dev,
 	list_for_each_entry_rcu(client, &dev->smi_clients, list) {
 		if (!kfd_smi_ev_enabled(pid, client, smi_event))
 			continue;
+
 		spin_lock(&client->lock);
-		if (kfifo_avail(&client->fifo) >= len) {
+		if (!client->drop_count && kfifo_avail(&client->fifo) >= len) {
 			kfifo_in(&client->fifo, event_msg, len);
 			wake_up_all(&client->wait_queue);
 		} else {
-			pr_debug("smi_event(EventID: %u): no space left\n",
-					smi_event);
+			client->drop_count++;
+			pr_debug("smi_event(EventID: %u): no space left drop_count %d\n",
+				 smi_event, client->drop_count);
 		}
 		spin_unlock(&client->lock);
 	}