Re: [RFC PATCH 3/4] vfio-ccw: Add a trace for asynchronous requests

[Steffen Maier <maier@linux.ibm.com>]

On 10/14/19 8:08 PM, Eric Farman wrote:
> Since the asynchronous requests are typically associated with
> error recovery, let's add a simple trace when one of those is
> issued to a device.
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> ---
>   drivers/s390/cio/vfio_ccw_fsm.c   |  4 ++++
>   drivers/s390/cio/vfio_ccw_trace.c |  1 +
>   drivers/s390/cio/vfio_ccw_trace.h | 26 ++++++++++++++++++++++++++
>   3 files changed, 31 insertions(+)
> 
> diff --git a/drivers/s390/cio/vfio_ccw_fsm.c b/drivers/s390/cio/vfio_ccw_fsm.c
> index d4119e4c4a8c..23648a9aa721 100644
> --- a/drivers/s390/cio/vfio_ccw_fsm.c
> +++ b/drivers/s390/cio/vfio_ccw_fsm.c
> @@ -341,6 +341,10 @@ static void fsm_async_request(struct vfio_ccw_private *private,
>   		/* should not happen? */
>   		cmd_region->ret_code = -EINVAL;
>   	}
> +
> +	trace_vfio_ccw_fsm_async_request(get_schid(private),
> +					 cmd_region->command,
> +					 cmd_region->ret_code);
>   }
> 
>   /*
> diff --git a/drivers/s390/cio/vfio_ccw_trace.c b/drivers/s390/cio/vfio_ccw_trace.c
> index b37bc68e7f18..37ecbf8be805 100644
> --- a/drivers/s390/cio/vfio_ccw_trace.c
> +++ b/drivers/s390/cio/vfio_ccw_trace.c
> @@ -9,5 +9,6 @@
>   #define CREATE_TRACE_POINTS
>   #include "vfio_ccw_trace.h"
> 
> +EXPORT_TRACEPOINT_SYMBOL(vfio_ccw_fsm_async_request);
>   EXPORT_TRACEPOINT_SYMBOL(vfio_ccw_fsm_event);
>   EXPORT_TRACEPOINT_SYMBOL(vfio_ccw_io_fctl);
> diff --git a/drivers/s390/cio/vfio_ccw_trace.h b/drivers/s390/cio/vfio_ccw_trace.h
> index 24a8152acfdf..4be2e36242e6 100644
> --- a/drivers/s390/cio/vfio_ccw_trace.h
> +++ b/drivers/s390/cio/vfio_ccw_trace.h
> @@ -17,6 +17,32 @@
> 
>   #include <linux/tracepoint.h>
> 
> +TRACE_EVENT(vfio_ccw_fsm_async_request,
> +	TP_PROTO(struct subchannel_id schid,
> +		 int command,
> +		 int errno),
> +	TP_ARGS(schid, command, errno),
> +
> +	TP_STRUCT__entry(
> +		__field_struct(struct subchannel_id, schid)

Not sure: Does this allow the user to filter for fields of struct subchannel_id 
or can the user express a filter on the entire combined struct subchannel_id?
In the preceding patch you have the 3 parts of schid as explicit separate trace 
fields in the tracepoint.

> +		__field(int, command)
> +		__field(int, errno)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->schid = schid;
> +		__entry->command = command;
> +		__entry->errno = errno;
> +	),
> +
> +	TP_printk("schid=%x.%x.%04x command=%d errno=%d",
> +		  __entry->schid.cssid,
> +		  __entry->schid.ssid,
> +		  __entry->schid.sch_no,
> +		  __entry->command,
> +		  __entry->errno)
> +);
> +
>   TRACE_EVENT(vfio_ccw_fsm_event,
>   	TP_PROTO(struct subchannel_id schid, int state, int event),
>   	TP_ARGS(schid, state, event),
> 


-- 
Mit freundlichen Gruessen / Kind regards
Steffen Maier

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