linux-kernel - Re: [tip:perf/core] perf probe: Add --list option for listing current probe events

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Date:	Tue, 01 Dec 2009 23:56:15 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Wang Liming <liming.wang@...driver.com>
CC:	mingo@...hat.com, peterz@...radead.org, fweisbec@...il.com,
	linux-kernel@...r.kernel.org, acme@...hat.com, rostedt@...dmis.org,
	jbaron@...hat.com, tglx@...utronix.de, fche@...hat.com,
	jkenisto@...ibm.com, hch@...radead.org, ananth@...ibm.com,
	srikar@...ux.vnet.ibm.com, prasad@...ux.vnet.ibm.com
Subject: Re: [tip:perf/core] perf probe: Add --list option for listing current
 probe events

Wang Liming wrote:
> Hi Masami,
> 
> tip-bot for Masami Hiramatsu wrote:
>> Commit-ID:  4de189fe6e5ad8241f6f8709d2e2ba4c3aeae33a
>> Gitweb:    
>> http://git.kernel.org/tip/4de189fe6e5ad8241f6f8709d2e2ba4c3aeae33a
>> Author:     Masami Hiramatsu <mhiramat@...hat.com>
>> AuthorDate: Mon, 30 Nov 2009 19:20:17 -0500
>> Committer:  Ingo Molnar <mingo@...e.hu>
>> CommitDate: Tue, 1 Dec 2009 08:20:02 +0100
>>
>> perf probe: Add --list option for listing current probe events
>>
>> Add --list option for listing currently defined probe events
>> in the kernel. This shows events in below format;
>>
>>  [group:event]    <perf-probe probe-definition>
>>
>> for example:
>>
>>  [probe:schedule_0]    schedule+30 cpu
>>
>> Note that source file/line information is not supported yet.
>> So even if you added a probe by line, it will be shown in
>> <symbol+offset>.
> ...
>> +
>> +    /* Scan event and group name. */
>> +    ret = sscanf(argv[0], "%c:%m[^/ \t]/%m[^ \t]",
>> +             &pr, group, event);
> "%m" are typos?

No, %m is glibc extension of sscanf modifier, which allocate
memory for scanned string in sscanf. You can see "man sscanf"
if your glibc is not so old (hopefully..). Please refer below;

http://www.kernel.org/doc/man-pages/online/pages/man3/scanf.3.html#NOTES

Anyway, thank you for reviewing!

>> +    if (ret != 3)
>> +        semantic_error("Failed to parse event name: %s", argv[0]);
>> +    pr_debug("Group:%s Event:%s probe:%c\n", *group, *event, pr);
>> +
>> +    if (!pp)
>> +        goto end;
>> +
>> +    pp->retprobe = (pr == 'r');
>> +
>> +    /* Scan function name and offset */
>> +    ret = sscanf(argv[1], "%m[^+]+%d", &pp->function, &pp->offset);
> the same error? fix attached below.
> 
> -- 
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index e42f3ac..8d46521 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -199,8 +199,8 @@ void parse_trace_kprobe_event(const char *str, char
> **group, char **event,
>          semantic_error("Too less arguments.");
> 
>      /* Scan event and group name. */
> -    ret = sscanf(argv[0], "%c:%m[^/ \t]/%m[^ \t]",
> -             &pr, group, event);
> +    ret = sscanf(argv[0], "%c:%s[^/ \t]/%s[^ \t]",
> +             &pr, *group, *event);
>      if (ret != 3)
>          semantic_error("Failed to parse event name: %s", argv[0]);
>      pr_debug("Group:%s Event:%s probe:%c\n", *group, *event, pr);
> @@ -211,7 +211,7 @@ void parse_trace_kprobe_event(const char *str, char
> **group, char **event,
>      pp->retprobe = (pr == 'r');
> 
>      /* Scan function name and offset */
> -    ret = sscanf(argv[1], "%m[^+]+%d", &pp->function, &pp->offset);
> +    ret = sscanf(argv[1], "%s[^+]+%d", pp->function, &pp->offset);
>      if (ret == 1)
>          pp->offset = 0;
> 
> 
> 
> 

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@...hat.com

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