libnvme: add support for ctrl diagnostic counters

Add support for retrieving ctrl diagnostic counters such as command_
error_count, reset_count and reconnect_count. These counters improve
visibility and can be useful for tools such as nvme-top to display
real-time statistics.

Unlike other sysfs attributes, these counters can change dynamically.
Annotate them with "!accessors:none" and provide custom implementations
to always retrieve the latest (non-cached) values.

Signed-off-by: Nilay Shroff <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Daniel Wagner <[email protected]>

Author: shroffni

libnvme/src/libnvme.ld

@@ -14,6 +14,9 @@ LIBNVME_3 {
 		libnvme_ctrl_get_subsysnqn;
 		libnvme_ctrl_get_subsystem;
 		libnvme_ctrl_get_transport_handle;
+		libnvme_ctrl_get_command_error_count;
+		libnvme_ctrl_get_reset_count;
+		libnvme_ctrl_get_reconnect_count;
 		libnvme_ctrl_identify;
 		libnvme_ctrl_match_config;
 		libnvme_ctrl_next_ns;

libnvme/src/nvme/private.h

@@ -298,6 +298,9 @@ struct libnvme_ctrl {			// !generate-accessors
 	bool unique_discovery_ctrl;
 	bool discovered;
 	bool persistent;
+	long command_error_count;	// !accessors:none
+	long reset_count;		// !accessors:none
+	long reconnect_count;		// !accessors:none
 	struct libnvme_fabrics_config cfg;
 };
 

libnvme/src/nvme/tree.c

@@ -1458,6 +1458,39 @@ __public const char *libnvme_ctrl_get_state(libnvme_ctrl_t c)
 	return c->state;
 }
 
+__public long libnvme_ctrl_get_command_error_count(libnvme_ctrl_t c)
+{
+	__cleanup_free char *error_count = NULL;
+
+	error_count = libnvme_get_ctrl_attr(c, "command_error_count");
+	if (error_count)
+		sscanf(error_count, "%ld", &c->command_error_count);
+
+	return c->command_error_count;
+}
+
+__public long libnvme_ctrl_get_reset_count(libnvme_ctrl_t c)
+{
+	__cleanup_free char *reset_count = NULL;
+
+	reset_count = libnvme_get_ctrl_attr(c, "reset_count");
+	if (reset_count)
+		sscanf(reset_count, "%ld", &c->reset_count);
+
+	return c->reset_count;
+}
+
+__public long libnvme_ctrl_get_reconnect_count(libnvme_ctrl_t c)
+{
+	__cleanup_free char *reconnect_count = NULL;
+
+	reconnect_count = libnvme_get_ctrl_attr(c, "reconnect_count");
+	if (reconnect_count)
+		sscanf(reconnect_count, "%ld", &c->reconnect_count);
+
+	return c->reconnect_count;
+}
+
 __public int libnvme_ctrl_identify(libnvme_ctrl_t c, struct nvme_id_ctrl *id)
 {
 	struct libnvme_transport_handle *hdl =

libnvme/src/nvme/tree.h

@@ -1007,6 +1007,31 @@ unsigned long long libnvme_ns_get_read_sectors(libnvme_ns_t n);
  */
 unsigned long long libnvme_ns_get_write_sectors(libnvme_ns_t n);
 
+/**
+ * libnvme_ctrl_get_command_error_count() - Get admin command error count
+ * @c: Controller instance
+ *
+ * Return: Number of times admin command issued to controller @c failed or
+ * returned error status
+ */
+long libnvme_ctrl_get_command_error_count(libnvme_ctrl_t c);
+
+/**
+ * libnvme_ctrl_get_reset_count() - Get controller reset count
+ * @c: Controller instance
+ *
+ * Return: Number of timer controller @c is reset
+ */
+long libnvme_ctrl_get_reset_count(libnvme_ctrl_t c);
+
+/**
+ * libnvme_ctrl_get_reconnect_count() - Get controller reconnect count
+ * @c: Controller instance
+ *
+ * Return: Number of times controller has to reconnect to the target
+ */
+long libnvme_ctrl_get_reconnect_count(libnvme_ctrl_t c);
+
 /**
  * libnvme_ctrl_identify() - Issues an 'identify controller' command
  * @c:	Controller instance