linux-kernel - Re: [PATCH 1/2] perf: convert: fix duplicate field names and avoid reserved keywords.

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Message-ID: <54BF8A97.6050402@huawei.com>
Date:	Wed, 21 Jan 2015 19:16:39 +0800
From:	Wang Nan <wangnan0@...wei.com>
To:	<jolsa@...hat.com>
CC:	<jeremie.galarneau@...icios.com>, <bigeasy@...utronix.de>,
	<lizefan@...wei.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] perf: convert: fix duplicate field names and avoid
 reserved keywords.

Hi Jiri,

I found that only this patch is not enough. When converting such tracepoints,
it uses add_tracepoint_fields_values(..., struct format_field *fields ...),
and fields->name is still the original one.

If 'struct format_field' has a field like 'dup_name' we can make things simpler.
However, struct format_field is part of traceevent, not only used by perf.

I have no enough time to think on it. Jiri, could you please give me some hints
so I can implement another patch tomorrow?

Thank you.

On 2015/1/21 11:23, Wang Nan wrote:
> Some parameters of syscall tracepoints named as 'nr', 'event', etc.
> When dealing with them, perf convert to ctf meets some problem:
> 
>  1. If a parameter with name 'nr', it will duplicate syscall's
>     common field 'nr'. One such syscall is io_submit().
> 
>  2. If a parameter with name 'event', it is denied to be inserted
>     because 'event' is a babeltrace keywork. One such syscall is
>     epoll_ctl.
> 
> This patch appends '_dupl_X' suffix to avoid problem 1, prepend a '_'
> prefix to avoid problem 2.
> 
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> ---
>  tools/perf/util/data-convert-bt.c | 65 ++++++++++++++++++++++++++++++++++++---
>  1 file changed, 61 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
> index ddecce8..b0a042d 100644
> --- a/tools/perf/util/data-convert-bt.c
> +++ b/tools/perf/util/data-convert-bt.c
> @@ -567,6 +567,38 @@ static int process_sample_event(struct perf_tool *tool,
>  	return cs ? 0 : -1;
>  }
>  
> +/* If dup < 0, add a prefix. Else, add _dupl_X suffix. */
> +static char *change_name(char *name, char *orig_name, int dup)
> +{
> +	char *new_name = NULL;
> +	size_t len;
> +
> +	if (!name)
> +		name = orig_name;
> +
> +	if (dup >= 10)
> +		goto out;
> +
> +	if (dup < 0)
> +		len = strlen(name) + sizeof("_");
> +	else
> +		len = strlen(orig_name) + sizeof("_dupl_X");
> +
> +	new_name = malloc(len);
> +	if (!new_name)
> +		goto out;
> +
> +	if (dup < 0)
> +		snprintf(new_name, len, "_%s", name);
> +	else
> +		snprintf(new_name, len, "%s_dupl_%d", orig_name, dup);
> +
> +out:
> +	if (name != orig_name)
> +		free(name);
> +	return new_name;
> +}
> +
>  static int add_tracepoint_fields_types(struct ctf_writer *cw,
>  				       struct format_field *fields,
>  				       struct bt_ctf_event_class *event_class)
> @@ -577,6 +609,9 @@ static int add_tracepoint_fields_types(struct ctf_writer *cw,
>  	for (field = fields; field; field = field->next) {
>  		struct bt_ctf_field_type *type;
>  		unsigned long flags = field->flags;
> +		struct bt_ctf_field_type *f = NULL;
> +		char *name;
> +		int dup = 1;
>  
>  		pr2("  field '%s'\n", field->name);
>  
> @@ -595,14 +630,36 @@ static int add_tracepoint_fields_types(struct ctf_writer *cw,
>  		if (flags & FIELD_IS_ARRAY)
>  			type = bt_ctf_field_type_array_create(type, field->arraylen);
>  
> -		ret = bt_ctf_event_class_add_field(event_class, type,
> -				field->name);
> +		/* Check name duplication */
> +		name = field->name;
> +		while (f = bt_ctf_event_class_get_field_by_name(event_class, name)) {
> +			bt_ctf_field_type_put(f);
> +			name = change_name(name, field->name, dup++);
> +			if (!name) {
> +				pr_err("Failed to create dup name for '%s'\n", field->name);
> +				return -1;
> +			}
> +		}
> +
> +		ret = bt_ctf_event_class_add_field(event_class, type, name);
> +		/* if failed, we may hit a keywork. try again with a '_' prefix */
> +		if (ret) {
> +			name = change_name(name, field->name, -1);
> +			if (!name) {
> +				pr_err("Failed to alloc name for '_%s'\n", field->name);
> +				return -1;
> +			}
> +			ret = bt_ctf_event_class_add_field(event_class, type, name);
> +		}
> +		if (name != field->name)
> +			free(name);
>  
>  		if (flags & FIELD_IS_ARRAY)
>  			bt_ctf_field_type_put(type);
>  
>  		if (ret) {
> -			pr_err("Failed to add field '%s\n", field->name);
> +			pr_err("Failed to add field '%s': %d\n",
> +					field->name, ret);
>  			return -1;
>  		}
>  	}
> @@ -646,7 +703,7 @@ static int add_generic_types(struct ctf_writer *cw, struct perf_evsel *evsel,
>  	do {								\
>  		pr2("  field '%s'\n", n);				\
>  		if (bt_ctf_event_class_add_field(cl, t, n)) {		\
> -			pr_err("Failed to add field '%s;\n", n);	\
> +			pr_err("Failed to add field '%s';\n", n);	\
>  			return -1;					\
>  		}							\
>  	} while (0)
> 


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