qcacmn: Add excessive logging detection

One of the most common stability issues encountered by the stability
team is watchdog bite due to excessive logging. Add a feature to track
logging to dmesg using a tumbling window and counter, and panic if the
configured maximum number of logs for that window is exceeded.

Change-Id: If83c6dfccb9d191b02a3a7166b065c0a0704f969
CRs-Fixed: 2338385

qdf/inc/qdf_time.h

@@ -115,6 +115,8 @@ static inline qdf_time_t qdf_system_ticks(void)
 	return __qdf_system_ticks();
 }
 
+#define qdf_system_ticks_per_sec __qdf_system_ticks_per_sec
+
 /**
  * qdf_system_ticks_to_msecs - convert ticks to milliseconds
  * @clock_ticks: Number of ticks

qdf/linux/src/i_qdf_time.h

@@ -122,6 +122,8 @@ static inline __qdf_time_t __qdf_system_ticks(void)
 	return jiffies;
 }
 
+#define __qdf_system_ticks_per_sec HZ
+
 /**
  * __qdf_system_ticks_to_msecs() - convert system ticks into milli seconds
  * @ticks: System ticks

utils/logging/src/wlan_logging_sock_svc.c

@@ -299,21 +299,61 @@ static int wlan_add_user_log_time_stamp(char *tbuf, size_t tbuf_sz, uint64_t ts)
 #endif /* QCA_WIFI_3_0_ADRASTEA */
 
 #ifdef CONFIG_MCL
+#ifdef WLAN_MAX_LOGS_PER_SEC
+static qdf_time_t __log_window_end_ticks;
+static qdf_atomic_t __log_window_count;
+
+/**
+ * assert_on_excessive_logging() - Check for and panic on excessive logging
+ *
+ * Track logging count using a quasi-tumbling window, 1 second long. If the max
+ * logging count for a given window is exceeded, panic.
+ *
+ * Return: None
+ */
+static void assert_on_excessive_logging(void)
+{
+	qdf_time_t now = qdf_system_ticks();
+
+	/*
+	 * If 'now' is more recent than the end of the window, reset.
+	 *
+	 * Note: This is not thread safe, and can result in more than one reset.
+	 * For our purposes, this is fine.
+	 */
+	if (qdf_system_time_after(now, __log_window_end_ticks)) {
+		__log_window_end_ticks = now + qdf_system_ticks_per_sec;
+		qdf_atomic_set(&__log_window_count, 0);
+	}
+
+	/* this _is_ thread safe, and results in at most one panic */
+	if (qdf_atomic_inc_return(&__log_window_count) == WLAN_MAX_LOGS_PER_SEC)
+		QDF_DEBUG_PANIC("Exceeded %d logs per second",
+				WLAN_MAX_LOGS_PER_SEC);
+}
+#else
+static inline void assert_on_excessive_logging(void) { }
+#endif /* WLAN_MAX_LOGS_PER_SEC */
+
 static inline void
 log_to_console(QDF_TRACE_LEVEL level, const char *timestamp, const char *msg)
 {
 	switch (level) {
 	case QDF_TRACE_LEVEL_FATAL:
 		pr_alert("%s %s\n", timestamp, msg);
+		assert_on_excessive_logging();
 		break;
 	case QDF_TRACE_LEVEL_ERROR:
 		pr_err("%s %s\n", timestamp, msg);
+		assert_on_excessive_logging();
 		break;
 	case QDF_TRACE_LEVEL_WARN:
 		pr_warn("%s %s\n", timestamp, msg);
+		assert_on_excessive_logging();
 		break;
 	case QDF_TRACE_LEVEL_INFO:
 		pr_info("%s %s\n", timestamp, msg);
+		assert_on_excessive_logging();
 		break;
 	case QDF_TRACE_LEVEL_INFO_HIGH:
 	case QDF_TRACE_LEVEL_INFO_MED: