scsi: iscsi: Capture iscsi debug messages using tracepoints

This commit enhances iscsi initiator modules to capture iscsi debug
messages using linux kernel tracepoint facility:

https://www.kernel.org/doc/Documentation/trace/tracepoints.txt

The following tracepoint events have been created under the iscsi
tracepoint event group:

iscsi_dbg_conn - to capture connection debug messages (libiscsi module)

iscsi_dbg_session - to capture session debug messages (libiscsi module)

iscsi_dbg_eh - to capture error handling debug messages (libiscsi module)

iscsi_dbg_tcp - to capture iscsi tcp debug messages (libiscsi_tcp module)

iscsi_dbg_sw_tcp - to capture iscsi sw tcp debug messages (iscsi_tcp module)

iscsi_dbg_trans_session - to cpature iscsi transsport sess debug messages
	(scsi_transport_iscsi module)

iscsi_dbg_trans_conn - to capture iscsi transport conn debug messages
	(scsi_transport_iscsi module)

[mkp: typos]

Signed-off-by: Fred Herard <fred.herard@oracle.com>
Reviewed-by: Rajan Shanmugavelu <rajan.shanmugavelu@oracle.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 107 insertions, 0 deletions

diff --git a/include/trace/events/iscsi.h b/include/trace/events/iscsi.h
new file mode 100644
index 000000000000..87408faf6e4e
--- /dev/null
+++ b/include/trace/events/iscsi.h
@@ -0,0 +1,107 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM iscsi
+
+#if !defined(_TRACE_ISCSI_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_ISCSI_H
+
+#include <linux/tracepoint.h>
+
+/* max debug message length */
+#define ISCSI_MSG_MAX	256
+
+/*
+ * Declare tracepoint helper function.
+ */
+void iscsi_dbg_trace(void (*trace)(struct device *dev, struct va_format *),
+		     struct device *dev, const char *fmt, ...);
+
+/*
+ * Declare event class for iscsi debug messages.
+ */
+DECLARE_EVENT_CLASS(iscsi_log_msg,
+
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf),
+
+	TP_STRUCT__entry(
+		__string(dname, 	dev_name(dev)		)
+		__dynamic_array(char,	msg, ISCSI_MSG_MAX	)
+	),
+
+	TP_fast_assign(
+		__assign_str(dname, dev_name(dev));
+		vsnprintf(__get_str(msg), ISCSI_MSG_MAX, vaf->fmt, *vaf->va);
+	),
+
+	TP_printk("%s: %s",__get_str(dname),  __get_str(msg)
+	)
+);
+
+/*
+ * Define event to capture iscsi connection debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_conn,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi session debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_session,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi error handling debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_eh,
+        TP_PROTO(struct device *dev, struct va_format *vaf),
+
+        TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi tcp debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_tcp,
+        TP_PROTO(struct device *dev, struct va_format *vaf),
+
+        TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi sw tcp debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_sw_tcp,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi transport session debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_trans_session,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+/*
+ * Define event to capture iscsi transport connection debug messages.
+ */
+DEFINE_EVENT(iscsi_log_msg, iscsi_dbg_trans_conn,
+	TP_PROTO(struct device *dev, struct va_format *vaf),
+
+	TP_ARGS(dev, vaf)
+);
+
+#endif /* _TRACE_ISCSI_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>