scsi: qla2xxx: add ring buffer for tracing debug logs

Having this log in a ring buffer helps to diagnose qla2xxx driver and
firmware issues instead of having to reproduce the problem with
extended_logging enabled. This saves cycles and helps when it is hard
to reproduce problem.

Link: https://lore.kernel.org/r/1581557368-32080-1-git-send-email-rajan.shanmugavelu@oracle.comReviewed-by: Joe Jin <joe.jin@oracle.com>
Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Rajan Shanmugavelu <rajan.shanmugavelu@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_dbg.c

@@ -73,6 +73,8 @@
 #include "qla_def.h"
 
 #include <linux/delay.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/qla.h>
 
 static uint32_t ql_dbg_offset = 0x800;
 
@@ -2537,15 +2539,30 @@ ql_dbg(uint level, scsi_qla_host_t *vha, uint id, const char *fmt, ...)
 {
 	va_list va;
 	struct va_format vaf;
-
-	if (!ql_mask_match(level))
-		return;
+	char pbuf[64];
 
 	va_start(va, fmt);
 
 	vaf.fmt = fmt;
 	vaf.va = &va;
 
+	if (!ql_mask_match(level)) {
+		if (vha != NULL) {
+			const struct pci_dev *pdev = vha->hw->pdev;
+			/* <module-name> <msg-id>:<host> Message */
+			snprintf(pbuf, sizeof(pbuf), "%s [%s]-%04x:%ld: ",
+			    QL_MSGHDR, dev_name(&(pdev->dev)), id,
+			    vha->host_no);
+		} else {
+			snprintf(pbuf, sizeof(pbuf), "%s [%s]-%04x: : ",
+			    QL_MSGHDR, "0000:00:00.0", id);
+		}
+		pbuf[sizeof(pbuf) - 1] = 0;
+		trace_ql_dbg_log(pbuf, &vaf);
+		va_end(va);
+		return;
+	}
+
 	if (vha != NULL) {
 		const struct pci_dev *pdev = vha->hw->pdev;
 		/* <module-name> <pci-name> <msg-id>:<host> Message */

include/trace/events/qla.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#if !defined(_TRACE_QLA_H_) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_QLA_H_
+
+#include <linux/tracepoint.h>
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM qla
+
+#define QLA_MSG_MAX 256
+
+DECLARE_EVENT_CLASS(qla_log_event,
+	TP_PROTO(const char *buf,
+		struct va_format *vaf),
+
+	TP_ARGS(buf, vaf),
+
+	TP_STRUCT__entry(
+		__string(buf, buf)
+		__dynamic_array(char, msg, QLA_MSG_MAX)
+	),
+	TP_fast_assign(
+		__assign_str(buf, buf);
+		vsnprintf(__get_str(msg), QLA_MSG_MAX, vaf->fmt, *vaf->va);
+	),
+
+	TP_printk("%s %s", __get_str(buf), __get_str(msg))
+);
+
+DEFINE_EVENT(qla_log_event, ql_dbg_log,
+	TP_PROTO(const char *buf, struct va_format *vaf),
+	TP_ARGS(buf, vaf)
+);
+
+#endif /* _TRACE_QLA_H */
+
+#define TRACE_INCLUDE_FILE qla
+
+#include <trace/define_trace.h>