firmware: arm_scmi: Account for failed debug initialization

When the SCMI debug subsystem fails to initialize, the related debug root
will be missing, and the underlying descriptor will be NULL.

Handle this fault condition in the SCMI debug helpers that maintain
metrics counters.

Fixes: 0b3d48c ("firmware: arm_scmi: Track basic SCMI communication debug metrics")
Signed-off-by: Cristian Marussi <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>

Author: cris-ma

drivers/firmware/arm_scmi/common.h

@@ -309,10 +309,28 @@ enum debug_counters {
 	SCMI_DEBUG_COUNTERS_LAST
 };
 
-static inline void scmi_inc_count(atomic_t *arr, int stat)
+/**
+ * struct scmi_debug_info  - Debug common info
+ * @top_dentry: A reference to the top debugfs dentry
+ * @name: Name of this SCMI instance
+ * @type: Type of this SCMI instance
+ * @is_atomic: Flag to state if the transport of this instance is atomic
+ * @counters: An array of atomic_c's used for tracking statistics (if enabled)
+ */
+struct scmi_debug_info {
+	struct dentry *top_dentry;
+	const char *name;
+	const char *type;
+	bool is_atomic;
+	atomic_t counters[SCMI_DEBUG_COUNTERS_LAST];
+};
+
+static inline void scmi_inc_count(struct scmi_debug_info *dbg, int stat)
 {
-	if (IS_ENABLED(CONFIG_ARM_SCMI_DEBUG_COUNTERS))
-		atomic_inc(&arr[stat]);
+	if (IS_ENABLED(CONFIG_ARM_SCMI_DEBUG_COUNTERS)) {
+		if (dbg)
+			atomic_inc(&dbg->counters[stat]);
+	}
 }
 
 static inline void scmi_dec_count(atomic_t *arr, int stat)

drivers/firmware/arm_scmi/driver.c

@@ -115,22 +115,6 @@ struct scmi_protocol_instance {
 
 #define ph_to_pi(h)	container_of(h, struct scmi_protocol_instance, ph)
 
-/**
- * struct scmi_debug_info  - Debug common info
- * @top_dentry: A reference to the top debugfs dentry
- * @name: Name of this SCMI instance
- * @type: Type of this SCMI instance
- * @is_atomic: Flag to state if the transport of this instance is atomic
- * @counters: An array of atomic_c's used for tracking statistics (if enabled)
- */
-struct scmi_debug_info {
-	struct dentry *top_dentry;
-	const char *name;
-	const char *type;
-	bool is_atomic;
-	atomic_t counters[SCMI_DEBUG_COUNTERS_LAST];
-};
-
 /**
  * struct scmi_info - Structure representing a SCMI instance
  *
@@ -1034,7 +1018,7 @@ scmi_xfer_command_acquire(struct scmi_chan_info *cinfo, u32 msg_hdr)
 		spin_unlock_irqrestore(&minfo->xfer_lock, flags);
 
 		scmi_bad_message_trace(cinfo, msg_hdr, MSG_UNEXPECTED);
-		scmi_inc_count(info->dbg->counters, ERR_MSG_UNEXPECTED);
+		scmi_inc_count(info->dbg, ERR_MSG_UNEXPECTED);
 
 		return xfer;
 	}
@@ -1062,7 +1046,7 @@ scmi_xfer_command_acquire(struct scmi_chan_info *cinfo, u32 msg_hdr)
 			msg_type, xfer_id, msg_hdr, xfer->state);
 
 		scmi_bad_message_trace(cinfo, msg_hdr, MSG_INVALID);
-		scmi_inc_count(info->dbg->counters, ERR_MSG_INVALID);
+		scmi_inc_count(info->dbg, ERR_MSG_INVALID);
 
 		/* On error the refcount incremented above has to be dropped */
 		__scmi_xfer_put(minfo, xfer);
@@ -1107,7 +1091,7 @@ static void scmi_handle_notification(struct scmi_chan_info *cinfo,
 			PTR_ERR(xfer));
 
 		scmi_bad_message_trace(cinfo, msg_hdr, MSG_NOMEM);
-		scmi_inc_count(info->dbg->counters, ERR_MSG_NOMEM);
+		scmi_inc_count(info->dbg, ERR_MSG_NOMEM);
 
 		scmi_clear_channel(info, cinfo);
 		return;
@@ -1123,7 +1107,7 @@ static void scmi_handle_notification(struct scmi_chan_info *cinfo,
 	trace_scmi_msg_dump(info->id, cinfo->id, xfer->hdr.protocol_id,
 			    xfer->hdr.id, "NOTI", xfer->hdr.seq,
 			    xfer->hdr.status, xfer->rx.buf, xfer->rx.len);
-	scmi_inc_count(info->dbg->counters, NOTIFICATION_OK);
+	scmi_inc_count(info->dbg, NOTIFICATION_OK);
 
 	scmi_notify(cinfo->handle, xfer->hdr.protocol_id,
 		    xfer->hdr.id, xfer->rx.buf, xfer->rx.len, ts);
@@ -1183,10 +1167,10 @@ static void scmi_handle_response(struct scmi_chan_info *cinfo,
 	if (xfer->hdr.type == MSG_TYPE_DELAYED_RESP) {
 		scmi_clear_channel(info, cinfo);
 		complete(xfer->async_done);
-		scmi_inc_count(info->dbg->counters, DELAYED_RESPONSE_OK);
+		scmi_inc_count(info->dbg, DELAYED_RESPONSE_OK);
 	} else {
 		complete(&xfer->done);
-		scmi_inc_count(info->dbg->counters, RESPONSE_OK);
+		scmi_inc_count(info->dbg, RESPONSE_OK);
 	}
 
 	if (IS_ENABLED(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT)) {
@@ -1296,7 +1280,7 @@ static int scmi_wait_for_reply(struct device *dev, const struct scmi_desc *desc,
 					"timed out in resp(caller: %pS) - polling\n",
 					(void *)_RET_IP_);
 				ret = -ETIMEDOUT;
-				scmi_inc_count(info->dbg->counters, XFERS_RESPONSE_POLLED_TIMEOUT);
+				scmi_inc_count(info->dbg, XFERS_RESPONSE_POLLED_TIMEOUT);
 			}
 		}
 
@@ -1321,7 +1305,7 @@ static int scmi_wait_for_reply(struct device *dev, const struct scmi_desc *desc,
 					    "RESP" : "resp",
 					    xfer->hdr.seq, xfer->hdr.status,
 					    xfer->rx.buf, xfer->rx.len);
-			scmi_inc_count(info->dbg->counters, RESPONSE_POLLED_OK);
+			scmi_inc_count(info->dbg, RESPONSE_POLLED_OK);
 
 			if (IS_ENABLED(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT)) {
 				scmi_raw_message_report(info->raw, xfer,
@@ -1336,7 +1320,7 @@ static int scmi_wait_for_reply(struct device *dev, const struct scmi_desc *desc,
 			dev_err(dev, "timed out in resp(caller: %pS)\n",
 				(void *)_RET_IP_);
 			ret = -ETIMEDOUT;
-			scmi_inc_count(info->dbg->counters, XFERS_RESPONSE_TIMEOUT);
+			scmi_inc_count(info->dbg, XFERS_RESPONSE_TIMEOUT);
 		}
 	}
 
@@ -1420,13 +1404,13 @@ static int do_xfer(const struct scmi_protocol_handle *ph,
 	    !is_transport_polling_capable(info->desc)) {
 		dev_warn_once(dev,
 			      "Polling mode is not supported by transport.\n");
-		scmi_inc_count(info->dbg->counters, SENT_FAIL_POLLING_UNSUPPORTED);
+		scmi_inc_count(info->dbg, SENT_FAIL_POLLING_UNSUPPORTED);
 		return -EINVAL;
 	}
 
 	cinfo = idr_find(&info->tx_idr, pi->proto->id);
 	if (unlikely(!cinfo)) {
-		scmi_inc_count(info->dbg->counters, SENT_FAIL_CHANNEL_NOT_FOUND);
+		scmi_inc_count(info->dbg, SENT_FAIL_CHANNEL_NOT_FOUND);
 		return -EINVAL;
 	}
 	/* True ONLY if also supported by transport. */
@@ -1461,19 +1445,19 @@ static int do_xfer(const struct scmi_protocol_handle *ph,
 	ret = info->desc->ops->send_message(cinfo, xfer);
 	if (ret < 0) {
 		dev_dbg(dev, "Failed to send message %d\n", ret);
-		scmi_inc_count(info->dbg->counters, SENT_FAIL);
+		scmi_inc_count(info->dbg, SENT_FAIL);
 		return ret;
 	}
 
 	trace_scmi_msg_dump(info->id, cinfo->id, xfer->hdr.protocol_id,
 			    xfer->hdr.id, "CMND", xfer->hdr.seq,
 			    xfer->hdr.status, xfer->tx.buf, xfer->tx.len);
-	scmi_inc_count(info->dbg->counters, SENT_OK);
+	scmi_inc_count(info->dbg, SENT_OK);
 
 	ret = scmi_wait_for_message_response(cinfo, xfer);
 	if (!ret && xfer->hdr.status) {
 		ret = scmi_to_linux_errno(xfer->hdr.status);
-		scmi_inc_count(info->dbg->counters, ERR_PROTOCOL);
+		scmi_inc_count(info->dbg, ERR_PROTOCOL);
 	}
 
 	if (info->desc->ops->mark_txdone)