Re: [PATCH] iscsi: Capture iscsi debug messages using tracepoints

[Douglas Gilbert <dgilbert-qazKcTl6WRFWk0Htik3J/w@public.gmane.org>]

Lee,
See about 3/4 of the way down your patch.

Summary: how about generalizing the message logging to tracefs so the
whole SCSI subsystem can use it?

Doug Gilbert


On 2018-11-26 8:01 p.m., Lee Duncan wrote:
> On 11/21/18 9:04 AM, fred.herard-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org wrote:
>> From: Fred Herard <fred.herard-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>>
>> 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 trasnsport sess debug messages
>> 	(scsi_transport_iscsi module)
>> iscsi_dbg_trans_conn - to capture iscsi tansport conn debug messages
>> 	(scsi_transport_iscsi module)
>>
>> Signed-off-by: Fred Herard <fred.herard-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>> Reviewed-by: Rajan Shanmugavelu <rajan.shanmugavelu-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>> ---
>>   drivers/scsi/iscsi_tcp.c            |   4 ++
>>   drivers/scsi/libiscsi.c             |  10 +++
>>   drivers/scsi/libiscsi_tcp.c         |   4 ++
>>   drivers/scsi/scsi_transport_iscsi.c |  34 ++++++++-
>>   include/trace/events/iscsi.h        | 107 ++++++++++++++++++++++++++++
>>   5 files changed, 158 insertions(+), 1 deletion(-)
>>   create mode 100644 include/trace/events/iscsi.h
>>
>> diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
>> index e11eff6b0e97..cf6475af72b1 100644
>> --- a/drivers/scsi/iscsi_tcp.c
>> +++ b/drivers/scsi/iscsi_tcp.c
>> @@ -44,6 +44,7 @@
>>   #include <scsi/scsi_host.h>
>>   #include <scsi/scsi.h>
>>   #include <scsi/scsi_transport_iscsi.h>
>> +#include <trace/events/iscsi.h>
>>   
>>   #include "iscsi_tcp.h"
>>   
>> @@ -72,6 +73,9 @@ MODULE_PARM_DESC(debug_iscsi_tcp, "Turn on debugging for iscsi_tcp module "
>>   			iscsi_conn_printk(KERN_INFO, _conn,	\
>>   					     "%s " dbg_fmt,	\
>>   					     __func__, ##arg);	\
>> +		iscsi_dbg_trace(trace_iscsi_dbg_sw_tcp,		\
>> +				&(_conn)->cls_conn->dev,	\
>> +				"%s " dbg_fmt, __func__, ##arg);\
>>   	} while (0);
>>   
>>   
>> diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
>> index cf8a15e54d83..088e90308c1f 100644
>> --- a/drivers/scsi/libiscsi.c
>> +++ b/drivers/scsi/libiscsi.c
>> @@ -40,6 +40,7 @@
>>   #include <scsi/scsi_transport.h>
>>   #include <scsi/scsi_transport_iscsi.h>
>>   #include <scsi/libiscsi.h>
>> +#include <trace/events/iscsi.h>
>>   
>>   static int iscsi_dbg_lib_conn;
>>   module_param_named(debug_libiscsi_conn, iscsi_dbg_lib_conn, int,
>> @@ -68,6 +69,9 @@ MODULE_PARM_DESC(debug_libiscsi_eh,
>>   			iscsi_conn_printk(KERN_INFO, _conn,	\
>>   					     "%s " dbg_fmt,	\
>>   					     __func__, ##arg);	\
>> +		iscsi_dbg_trace(trace_iscsi_dbg_conn,		\
>> +				&(_conn)->cls_conn->dev,	\
>> +				"%s " dbg_fmt, __func__, ##arg);\
>>   	} while (0);
>>   
>>   #define ISCSI_DBG_SESSION(_session, dbg_fmt, arg...)			\
>> @@ -76,6 +80,9 @@ MODULE_PARM_DESC(debug_libiscsi_eh,
>>   			iscsi_session_printk(KERN_INFO, _session,	\
>>   					     "%s " dbg_fmt,		\
>>   					     __func__, ##arg);		\
>> +		iscsi_dbg_trace(trace_iscsi_dbg_session, 		\
>> +				&(_session)->cls_session->dev,		\
>> +				"%s " dbg_fmt, __func__, ##arg);	\
>>   	} while (0);
>>   
>>   #define ISCSI_DBG_EH(_session, dbg_fmt, arg...)				\
>> @@ -84,6 +91,9 @@ MODULE_PARM_DESC(debug_libiscsi_eh,
>>   			iscsi_session_printk(KERN_INFO, _session,	\
>>   					     "%s " dbg_fmt,		\
>>   					     __func__, ##arg);		\
>> +		iscsi_dbg_trace(trace_iscsi_dbg_eh,			\
>> +				&(_session)->cls_session->dev,		\
>> +				"%s " dbg_fmt, __func__, ##arg);	\
>>   	} while (0);
>>   
>>   inline void iscsi_conn_queue_work(struct iscsi_conn *conn)
>> diff --git a/drivers/scsi/libiscsi_tcp.c b/drivers/scsi/libiscsi_tcp.c
>> index 63a1d69ff515..d641a72ae033 100644
>> --- a/drivers/scsi/libiscsi_tcp.c
>> +++ b/drivers/scsi/libiscsi_tcp.c
>> @@ -43,6 +43,7 @@
>>   #include <scsi/scsi_host.h>
>>   #include <scsi/scsi.h>
>>   #include <scsi/scsi_transport_iscsi.h>
>> +#include <trace/events/iscsi.h>
>>   
>>   #include "iscsi_tcp.h"
>>   
>> @@ -65,6 +66,9 @@ MODULE_PARM_DESC(debug_libiscsi_tcp, "Turn on debugging for libiscsi_tcp "
>>   			iscsi_conn_printk(KERN_INFO, _conn,	\
>>   					     "%s " dbg_fmt,	\
>>   					     __func__, ##arg);	\
>> +		iscsi_dbg_trace(trace_iscsi_dbg_tcp,		\
>> +				&(_conn)->cls_conn->dev,	\
>> +				"%s " dbg_fmt, __func__, ##arg);\
>>   	} while (0);
>>   
>>   static int iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
>> diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
>> index f6542c159ed6..58e0310ce258 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;
>> 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,

Could the "i" be dropped from the start of that name, that is:
     DECLARE_EVENT_CLASS(scsi_log_msg,

and that and the definition that follows be moved into
     include/trace/events/scsi.h ??

That would make it available to all the current SCSI upper level
drivers (e.g. the sg driver) and lower level drivers (e.g.
scsi_debug).

Doug Gilbert

-- 
You received this message because you are subscribed to the Google Groups "open-iscsi" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-iscsi+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To post to this group, send email to open-iscsi-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
Visit this group at https://groups.google.com/group/open-iscsi.
For more options, visit https://groups.google.com/d/optout.