Re: [RFC PATCH 07/10] scsi/trace: Use scsi_show_result trace point instead of printk

[Hannes Reinecke <hare@suse.de>]

On 08/08/2014 01:50 PM, Yoshihiro YUNOMAE wrote:
> Current SCSI trace has hostbyte table and driverbyte table, so we don't need to
> have the same table in scsi/constants.c.
>
> - Result examples
>
> <Before> (printk)
> sd 2:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
>
> <After> (ftrace)
> scsi_show_result: host_no=2 channel=0 id=0 lun=0 [sda] result=(driver=DRIVER_SENSE host=DID_OK)
>
> Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Doug Gilbert <dgilbert@interlog.com>
> Cc: Martin K. Petersen <martin.petersen@oracle.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
> Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> ---
>   drivers/scsi/constants.c    |   52 -------------------------------------------
>   drivers/scsi/scsi_trace.c   |   16 +++++++++++++
>   include/trace/events/scsi.h |   38 +++++++++++++++++++++++++++++++
>   3 files changed, 53 insertions(+), 53 deletions(-)
>
> diff --git a/drivers/scsi/constants.c b/drivers/scsi/constants.c
> index 6fad6b4..f7b7f32 100644
> --- a/drivers/scsi/constants.c
> +++ b/drivers/scsi/constants.c
> @@ -1488,55 +1488,3 @@ void scsi_print_sense(struct scsi_cmnd *cmd)
>   			   SCSI_SENSE_BUFFERSIZE);
>   }
>   EXPORT_SYMBOL(scsi_print_sense);
> -
> -#ifdef CONFIG_SCSI_CONSTANTS
> -
> -static const char * const hostbyte_table[]={
> -"DID_OK", "DID_NO_CONNECT", "DID_BUS_BUSY", "DID_TIME_OUT", "DID_BAD_TARGET",
> -"DID_ABORT", "DID_PARITY", "DID_ERROR", "DID_RESET", "DID_BAD_INTR",
> -"DID_PASSTHROUGH", "DID_SOFT_ERROR", "DID_IMM_RETRY", "DID_REQUEUE",
> -"DID_TRANSPORT_DISRUPTED", "DID_TRANSPORT_FAILFAST", "DID_TARGET_FAILURE",
> -"DID_NEXUS_FAILURE" };
> -#define NUM_HOSTBYTE_STRS ARRAY_SIZE(hostbyte_table)
> -
> -static const char * const driverbyte_table[]={
> -"DRIVER_OK", "DRIVER_BUSY", "DRIVER_SOFT",  "DRIVER_MEDIA", "DRIVER_ERROR",
> -"DRIVER_INVALID", "DRIVER_TIMEOUT", "DRIVER_HARD", "DRIVER_SENSE"};
> -#define NUM_DRIVERBYTE_STRS ARRAY_SIZE(driverbyte_table)
> -
> -void scsi_show_result(struct scsi_device *sdev, const char *name, int result)
> -{
> -	int hb = host_byte(result);
> -	int db = driver_byte(result);
> -	const char *hb_string;
> -	const char *db_string;
> -
> -	hb_string = (hb < NUM_HOSTBYTE_STRS) ? hostbyte_table[hb] : "invalid";
> -	db_string = (db < NUM_DRIVERBYTE_STRS) ?
> -		driverbyte_table[db] : "invalid";
> -
> -
> -	sdev_printk(KERN_INFO, sdev,
> -		    "[%s] Result: hostbyte=%s driverbyte=%s\n",
> -		    name, hb_string, db_string);
> -}
> -
> -#else
> -
> -void scsi_show_result(struct scsi_device *sdev, const char *name, int result)
> -{
> -	sdev_printk(KERN_INFO, sdev,
> -		    "[%s] Result: hostbyte=0x%02x driverbyte=0x%02x\n",
> -		    name, host_byte(result), driver_byte(result));
> -}
> -
> -#endif
> -EXPORT_SYMBOL(scsi_show_result);
> -
> -void scsi_print_result(struct scsi_cmnd *cmd)
> -{
> -	const char *devname = cmd->request->rq_disk ?
> -		cmd->request->rq_disk->disk_name : "scsi";
> -	scsi_show_result(cmd->device, devname, cmd->result);
> -}
> -EXPORT_SYMBOL(scsi_print_result);
> diff --git a/drivers/scsi/scsi_trace.c b/drivers/scsi/scsi_trace.c
> index 2bea4f0..6ffbc40 100644
> --- a/drivers/scsi/scsi_trace.c
> +++ b/drivers/scsi/scsi_trace.c
> @@ -19,6 +19,8 @@
>   #include <linux/trace_seq.h>
>   #include <trace/events/scsi.h>
>
> +#include <scsi/scsi_dbg.h>
> +
>   #define SERVICE_ACTION16(cdb) (cdb[1] & 0x1f)
>   #define SERVICE_ACTION32(cdb) ((cdb[8] << 8) | cdb[9])
>
> @@ -286,3 +288,17 @@ scsi_trace_parse_cdb(struct trace_seq *p, unsigned char *cdb, int len)
>   		return scsi_trace_misc(p, cdb, len);
>   	}
>   }
> +
> +void scsi_show_result(struct scsi_device *sdev, const char *name, int result)
> +{
> +	trace_scsi_show_result(sdev, name, result);
> +}
> +EXPORT_SYMBOL(scsi_show_result);
> +
> +void scsi_print_result(struct scsi_cmnd *cmd)
> +{
> +	const char *devname = cmd->request->rq_disk ?
> +		cmd->request->rq_disk->disk_name : "scsi";
> +	scsi_show_result(cmd->device, devname, cmd->result);
> +}
> +EXPORT_SYMBOL(scsi_print_result);
> diff --git a/include/trace/events/scsi.h b/include/trace/events/scsi.h
> index 8aecdc2..0675195 100644
> --- a/include/trace/events/scsi.h
> +++ b/include/trace/events/scsi.h
> @@ -123,7 +123,11 @@
>   		scsi_hostbyte_name(DID_IMM_RETRY),		\
>   		scsi_hostbyte_name(DID_REQUEUE),		\
>   		scsi_hostbyte_name(DID_TRANSPORT_DISRUPTED),	\
> -		scsi_hostbyte_name(DID_TRANSPORT_FAILFAST))
> +		scsi_hostbyte_name(DID_TRANSPORT_FAILFAST),	\
> +		scsi_hostbyte_name(DID_TARGET_FAILURE),		\
> +		scsi_hostbyte_name(DID_NEXUS_FAILURE),		\
> +		scsi_hostbyte_name(DID_ALLOC_FAILURE),		\
> +		scsi_hostbyte_name(DID_MEDIUM_ERROR))
>
>   #define scsi_driverbyte_name(result)	{ result, #result }
>   #define show_driverbyte_name(val)				\
> @@ -359,6 +363,38 @@ TRACE_EVENT(scsi_eh_wakeup,
>   	TP_printk("host_no=%u", __entry->host_no)
>   );
>
> +TRACE_EVENT(scsi_show_result,
> +
> +	TP_PROTO(struct scsi_device *sdev, const char *devname, int result),
> +
> +	TP_ARGS(sdev, devname, result),
> +
> +	TP_STRUCT__entry(
> +		__field( unsigned int,	host_no	)
> +		__field( unsigned int,	channel	)
> +		__field( unsigned int,	id	)
> +		__field( unsigned int,	lun	)
> +		__string(devname,	devname	)
> +		__field( int,		result	)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->host_no	= sdev->host->host_no;
> +		__entry->channel	= sdev->channel;
> +		__entry->id		= sdev->id;
> +		__entry->lun		= sdev->lun;
> +		__assign_str(devname, devname);
> +		__entry->result		= result;
> +	),
> +
> +	TP_printk("host_no=%u channel=%u id=%u lun=%u [%s] result=(driver=%s "\
> +		  "host=%s)",
> +		  __entry->host_no, __entry->channel, __entry->id, __entry->lun,
> +		  __get_str(devname),
> +		  show_driverbyte_name(driver_byte(__entry->result)),
> +		  show_hostbyte_name(host_byte(__entry->result)))
> +);
> +
>   #endif /*  _TRACE_SCSI_H */
>
>   /* This part must be outside protection */
>
> --
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>
Hmm.
I'm not sure this is the correct way.
Currently we have quite some code duplication in scsi_trace.c and 
constants.c, correct.
So I definitely would like to see them both merged.

But constants.c is influenced by CONFIG_SCSI_CONSTANTS, whereas
scsi_trace isn't, and the functions in constants.c are used 
throughout the scsi stack.
So I'd rather see to have scsi_trace to be updated to use the 
functions from constants.c, and remove the duplicate code in
scsi_trace.

At a later step we should be working on removing/replacing existing 
logging code in the SCSI stack with trace points, but that should be
reserved for a separate patchset.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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