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, 33 insertions, 1 deletions

diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 6fd2fe210fc3..ffae269819b3 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -37,6 +37,18 @@
 
 #define ISCSI_TRANSPORT_VERSION "2.0-870"
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/iscsi.h>
+
+/*
+ * Export tracepoint symbols to be used by other modules.
+ */
+EXPORT_TRACEPOINT_SYMBOL_GPL(iscsi_dbg_conn);
+EXPORT_TRACEPOINT_SYMBOL_GPL(iscsi_dbg_eh);
+EXPORT_TRACEPOINT_SYMBOL_GPL(iscsi_dbg_session);
+EXPORT_TRACEPOINT_SYMBOL_GPL(iscsi_dbg_tcp);
+EXPORT_TRACEPOINT_SYMBOL_GPL(iscsi_dbg_sw_tcp);
+
 static int dbg_session;
 module_param_named(debug_session, dbg_session, int,
 		   S_IRUGO | S_IWUSR);
@@ -59,6 +71,9 @@ MODULE_PARM_DESC(debug_conn,
 			iscsi_cls_session_printk(KERN_INFO, _session,	\
 						 "%s: " dbg_fmt,	\
 						 __func__, ##arg);	\
+		iscsi_dbg_trace(trace_iscsi_dbg_trans_session,		\
+				&(_session)->dev,			\
+				"%s " dbg_fmt, __func__, ##arg);	\
 	} while (0);
 
 #define ISCSI_DBG_TRANS_CONN(_conn, dbg_fmt, arg...)			\
@@ -66,7 +81,10 @@ MODULE_PARM_DESC(debug_conn,
 		if (dbg_conn)						\
 			iscsi_cls_conn_printk(KERN_INFO, _conn,		\
 					      "%s: " dbg_fmt,		\
-					      __func__, ##arg);	\
+					      __func__, ##arg);		\
+		iscsi_dbg_trace(trace_iscsi_dbg_trans_conn,		\
+				&(_conn)->dev,				\
+				"%s " dbg_fmt, __func__, ##arg);	\
 	} while (0);
 
 struct iscsi_internal {
@@ -4497,6 +4515,20 @@ int iscsi_unregister_transport(struct iscsi_transport *tt)
 }
 EXPORT_SYMBOL_GPL(iscsi_unregister_transport);
 
+void iscsi_dbg_trace(void (*trace)(struct device *dev, struct va_format *),
+		     struct device *dev, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+	trace(dev, &vaf);
+	va_end(args);
+}
+EXPORT_SYMBOL_GPL(iscsi_dbg_trace);
+
 static __init int iscsi_transport_init(void)
 {
 	int err;