Re: [PATCH v8 16/24] drivers/fsi: Add tracepoints for low-level operations

[Steven Rostedt <rostedt@goodmis.org>]

On Tue,  6 Jun 2017 16:08:51 -0500
Christopher Bostic <cbostic@linux.vnet.ibm.com> wrote:

> From: Jeremy Kerr <jk@ozlabs.org>
> 
> Trace low level read and write FSI bus operations.
> 
> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
> Signed-off-by: Joel Stanley <joel@jms.id.au>
> Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
> ---
> v8 - type cast to 'int' to clean up build warnings
> ---
>  drivers/fsi/fsi-core.c     |  27 +++++++---
>  include/trace/events/fsi.h | 127 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 148 insertions(+), 6 deletions(-)
>  create mode 100644 include/trace/events/fsi.h
> 
> diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
> index 3681365..db54561 100644
> --- a/drivers/fsi/fsi-core.c
> +++ b/drivers/fsi/fsi-core.c
> @@ -23,6 +23,9 @@
>  
>  #include "fsi-master.h"
>  
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/fsi.h>
> +
>  #define FSI_SLAVE_CONF_NEXT_MASK	GENMASK(31, 31)
>  #define FSI_SLAVE_CONF_SLOTS_MASK	GENMASK(23, 16)
>  #define FSI_SLAVE_CONF_SLOTS_SHIFT	16
> @@ -542,11 +545,16 @@ static int fsi_master_read(struct fsi_master *master, int link,
>  {
>  	int rc;
>  
> +	trace_fsi_master_read(master, link, slave_id, addr, size);
> +
>  	rc = fsi_check_access(addr, size);
> -	if (rc)
> -		return rc;
> +	if (!rc)
> +		rc = master->read(master, link, slave_id, addr, val, size);
> +
> +	trace_fsi_master_rw_result(master, link, slave_id, addr, size,
> +			false, val, rc);
>  
> -	return master->read(master, link, slave_id, addr, val, size);
> +	return rc;
>  }
>  
>  static int fsi_master_write(struct fsi_master *master, int link,
> @@ -554,11 +562,16 @@ static int fsi_master_write(struct fsi_master *master, int link,
>  {
>  	int rc;
>  
> +	trace_fsi_master_write(master, link, slave_id, addr, size, val);
> +
>  	rc = fsi_check_access(addr, size);
> -	if (rc)
> -		return rc;
> +	if (!rc)
> +		rc = master->write(master, link, slave_id, addr, val, size);
>  
> -	return master->write(master, link, slave_id, addr, val, size);
> +	trace_fsi_master_rw_result(master, link, slave_id, addr, size,
> +			true, val, rc);
> +
> +	return rc;
>  }
>  
>  static int fsi_master_link_enable(struct fsi_master *master, int link)
> @@ -574,6 +587,8 @@ static int fsi_master_link_enable(struct fsi_master *master, int link)
>   */
>  static int fsi_master_break(struct fsi_master *master, int link)
>  {
> +	trace_fsi_master_break(master, link);
> +
>  	if (master->send_break)
>  		return master->send_break(master, link);
>  
> diff --git a/include/trace/events/fsi.h b/include/trace/events/fsi.h
> new file mode 100644
> index 0000000..697ee66
> --- /dev/null
> +++ b/include/trace/events/fsi.h
> @@ -0,0 +1,127 @@
> +
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM fsi
> +
> +#if !defined(_TRACE_FSI_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_FSI_H
> +
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(fsi_master_read,
> +	TP_PROTO(const struct fsi_master *master, int link, int id,
> +			uint32_t addr, size_t size),
> +	TP_ARGS(master, link, id, addr, size),
> +	TP_STRUCT__entry(
> +		__field(int,	master_idx)
> +		__field(int,	link)
> +		__field(int,	id)
> +		__field(__u32,	addr)
> +		__field(size_t,	size)
> +	),
> +	TP_fast_assign(
> +		__entry->master_idx = master->idx;
> +		__entry->link = link;
> +		__entry->id = id;
> +		__entry->addr = addr;
> +		__entry->size = size;
> +	),
> +	TP_printk("fsi%d:%02d:%02d %08x[%zd]",
> +		__entry->master_idx,
> +		__entry->link,
> +		__entry->id,
> +		__entry->addr,
> +		__entry->size
> +	)
> +);
> +
> +TRACE_EVENT(fsi_master_write,
> +	TP_PROTO(const struct fsi_master *master, int link, int id,
> +			uint32_t addr, size_t size, const void *data),
> +	TP_ARGS(master, link, id, addr, size, data),
> +	TP_STRUCT__entry(
> +		__field(int,	master_idx)
> +		__field(int,	link)
> +		__field(int,	id)
> +		__field(__u32,	addr)
> +		__field(size_t,	size)
> +		__field(__u32,	data)
> +	),
> +	TP_fast_assign(
> +		__entry->master_idx = master->idx;
> +		__entry->link = link;
> +		__entry->id = id;
> +		__entry->addr = addr;
> +		__entry->size = size;
> +		__entry->data = 0;
> +		memcpy(&__entry->data, data, size);


Um, can size ever be greater than 4? If so, this is a bug.

I think you may want to use a dynamic array here.

	TP_STRUCT__entry(
		[..]
		__dynamic_array(char, data, size)
	[..]

	TP_fast_assign(
		[..]
		memcpy(__get_dynamic_array(data), data, size);
	[..]

	TP_printk(...
		[..]
		__entry->size,
		__get_dynamic_array(data)

You may also want to look at __print_array() too.

Same with below.

-- Steve


> +	),
> +	TP_printk("fsi%d:%02d:%02d %08x[%zd] <= {%*ph}",
> +		__entry->master_idx,
> +		__entry->link,
> +		__entry->id,
> +		__entry->addr,
> +		__entry->size,
> +		(int)__entry->size, &__entry->data
> +	)
> +);
> +
> +TRACE_EVENT(fsi_master_rw_result,
> +	TP_PROTO(const struct fsi_master *master, int link, int id,
> +			uint32_t addr, size_t size,
> +			bool write, const void *data, int ret),
> +	TP_ARGS(master, link, id, addr, size, write, data, ret),
> +	TP_STRUCT__entry(
> +		__field(int,	master_idx)
> +		__field(int,	link)
> +		__field(int,	id)
> +		__field(__u32,	addr)
> +		__field(size_t,	size)
> +		__field(bool,	write)
> +		__field(__u32,	data)
> +		__field(int,	ret)
> +	),
> +	TP_fast_assign(
> +		__entry->master_idx = master->idx;
> +		__entry->link = link;
> +		__entry->id = id;
> +		__entry->addr = addr;
> +		__entry->size = size;
> +		__entry->write = write;
> +		__entry->data = 0;
> +		__entry->ret = ret;
> +		if (__entry->write || !__entry->ret)
> +			memcpy(&__entry->data, data, size);
> +	),
> +	TP_printk("fsi%d:%02d:%02d %08x[%zd] %s {%*ph} ret %d",
> +		__entry->master_idx,
> +		__entry->link,
> +		__entry->id,
> +		__entry->addr,
> +		__entry->size,
> +		__entry->write ? "<=" : "=>",
> +		(int)__entry->size, &__entry->data,
> +		__entry->ret
> +	)
> +);
> +
> +TRACE_EVENT(fsi_master_break,
> +	TP_PROTO(const struct fsi_master *master, int link),
> +	TP_ARGS(master, link),
> +	TP_STRUCT__entry(
> +		__field(int,	master_idx)
> +		__field(int,	link)
> +	),
> +	TP_fast_assign(
> +		__entry->master_idx = master->idx;
> +		__entry->link = link;
> +	),
> +	TP_printk("fsi%d:%d",
> +		__entry->master_idx,
> +		__entry->link
> +	)
> +);
> +
> +
> +#endif /* _TRACE_FSI_H */
> +
> +#include <trace/define_trace.h>