netdev - Re: [patch net-next 1/2] devlink: add hardware messages tracing facility

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Date:	Mon, 11 Jul 2016 12:08:14 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jiri Pirko <jiri@...nulli.us>
Cc:	netdev@...r.kernel.org, davem@...emloft.net, idosch@...lanox.com,
	yotamg@...lanox.com, eladr@...lanox.com, nogahf@...lanox.com,
	ogerlitz@...lanox.com, ivecera@...hat.com, mingo@...hat.com,
	jolsa@...nel.org
Subject: Re: [patch net-next 1/2] devlink: add hardware messages tracing
 facility

On Mon, 11 Jul 2016 15:18:47 +0200
Jiri Pirko <jiri@...nulli.us> wrote:

> From: Jiri Pirko <jiri@...lanox.com>
> 
> Define a tracepoint and allow user to trace messages going to and from
> hardware associated with devlink instance.
> 
> Signed-off-by: Jiri Pirko <jiri@...lanox.com>
> ---
>  include/net/devlink.h          |  8 +++++++
>  include/trace/events/devlink.h | 49 ++++++++++++++++++++++++++++++++++++++++++
>  net/core/devlink.c             |  9 ++++++++
>  3 files changed, 66 insertions(+)
>  create mode 100644 include/trace/events/devlink.h
> 
> diff --git a/include/net/devlink.h b/include/net/devlink.h
> index c99ffe8..865ade6 100644
> --- a/include/net/devlink.h
> +++ b/include/net/devlink.h
> @@ -115,6 +115,8 @@ struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size);
>  int devlink_register(struct devlink *devlink, struct device *dev);
>  void devlink_unregister(struct devlink *devlink);
>  void devlink_free(struct devlink *devlink);
> +void devlink_trace_hwmsg(const struct devlink *devlink, bool incoming,
> +			 unsigned long type, const u8 *buf, size_t len);
>  int devlink_port_register(struct devlink *devlink,
>  			  struct devlink_port *devlink_port,
>  			  unsigned int port_index);
> @@ -154,6 +156,12 @@ static inline void devlink_free(struct devlink *devlink)
>  	kfree(devlink);
>  }
>  
> +static inline void devlink_trace_hwmsg(const struct devlink *devlink,
> +				       bool incoming, unsigned long type,
> +				       const u8 *buf, size_t len);
> +{
> +}
> +
>  static inline int devlink_port_register(struct devlink *devlink,
>  					struct devlink_port *devlink_port,
>  					unsigned int port_index)
> diff --git a/include/trace/events/devlink.h b/include/trace/events/devlink.h
> new file mode 100644
> index 0000000..7918c57
> --- /dev/null
> +++ b/include/trace/events/devlink.h
> @@ -0,0 +1,49 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM devlink
> +
> +#if !defined(_TRACE_DEVLINK_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_DEVLINK_H
> +
> +#include <linux/device.h>
> +#include <net/devlink.h>
> +#include <linux/tracepoint.h>
> +
> +/*
> + * Tracepoint for devlink hardware message:
> + */
> +TRACE_EVENT(devlink_hwmsg,
> +	TP_PROTO(const struct devlink *devlink, bool incoming,
> +		 unsigned long type, const u8 *buf, size_t len),
> +
> +	TP_ARGS(devlink, incoming, type, buf, len),
> +
> +	TP_STRUCT__entry(
> +		__string(bus_name, devlink->dev->bus->name)
> +		__string(dev_name, dev_name(devlink->dev))
> +		__string(owner_name, devlink->dev->driver->owner->name)
> +		__field(bool, incoming)
> +		__field(unsigned long, type)
> +		__dynamic_array(u8, buf, len)
> +		__field(size_t, len)
> +	),
> +
> +	TP_fast_assign(
> +		__assign_str(bus_name, devlink->dev->bus->name);
> +		__assign_str(dev_name, dev_name(devlink->dev));
> +		__assign_str(owner_name, devlink->dev->driver->owner->name);
> +		__entry->incoming = incoming;
> +		__entry->type = type;
> +		memcpy(__get_dynamic_array(buf), buf, len);
> +		__entry->len = len;
> +	),
> +
> +	TP_printk("bus_name=%s dev_name=%s owner_name=%s incoming=%d type=%lu buf=0x[%*phD] len=%lu",
> +		  __get_str(bus_name), __get_str(dev_name),
> +		  __get_str(owner_name), __entry->incoming, __entry->type,
> +		  (int) __entry->len, __get_dynamic_array(buf), __entry->len)
> +);
> +
> +#endif /* _TRACE_DEVLINK_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/net/core/devlink.c b/net/core/devlink.c
> index b2e592a..8cfa3b0 100644
> --- a/net/core/devlink.c
> +++ b/net/core/devlink.c
> @@ -26,6 +26,8 @@
>  #include <net/net_namespace.h>
>  #include <net/sock.h>
>  #include <net/devlink.h>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/devlink.h>
>  
>  static LIST_HEAD(devlink_list);
>  
> @@ -1679,6 +1681,13 @@ void devlink_free(struct devlink *devlink)
>  }
>  EXPORT_SYMBOL_GPL(devlink_free);
>  
> +void devlink_trace_hwmsg(const struct devlink *devlink, bool incoming,
> +			 unsigned long type, const u8 *buf, size_t len)
> +{
> +	trace_devlink_hwmsg(devlink, incoming, type, buf, len);
> +}
> +EXPORT_SYMBOL_GPL(devlink_trace_hwmsg);
> +

Instead of having a function that always gets called even when tracing
isn't enabled, why not have the caller call the trace_devlink_hwmsg()
directly?

In the trace/devlink.h file you could encapsulate it with:

#if IS_ENABLED(CONFIG_NET_DEVLINK)

[...]

#else
static inline void trace_devlink_hwmsg(const struct devlink *devlink,
				       bool incoming, unsigned long type,
				       const u8 *buf, size_t len);
{
}
#endif

-- Steve

>  /**
>   *	devlink_port_register - Register devlink port
>   *