linux-kernel - Re: [PATCH v3 1/7] perf probe: Improve detection of file/function name in the probe pattern

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Message-ID: <20150428134612.GJ16849@kernel.org>
Date:	Tue, 28 Apr 2015 10:46:12 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
Cc:	masami.hiramatsu.pt@...achi.com, ananth@...ibm.com,
	mpe@...erman.id.au, sukadev@...ux.vnet.ibm.com,
	srikar@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v3 1/7] perf probe: Improve detection of file/function
 name in the probe pattern

Em Tue, Apr 28, 2015 at 05:35:34PM +0530, Naveen N. Rao escreveu:
> Currently, perf probe considers patterns including a '.' to be a file.
> However, this causes problems on powerpc ABIv1 where all functions have
> a leading '.':
> 
>   $ perf probe -F | grep schedule_timeout_interruptible
>   .schedule_timeout_interruptible
>   $ perf probe .schedule_timeout_interruptible
>   Semantic error :File always requires line number or lazy pattern.
>     Error: Command Parse Error.

Just gave this a real quick look, saw no problems, but I'll defer this
to Masami, a reviewed-by tag from him, ok Masami?

- Arnaldo
 
> Fix this:
> - by checking the probe pattern in more detail, and
> - skipping leading dot if one exists when creating/deleting events.
> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
> Reviewed-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
> ---
> Changes:
> - Folded initial part of patch 04 [now 03] into this per Masami.
> - Moved to using a bool file_spec and some whitespace changes.
> 
> 
>  tools/perf/util/probe-event.c | 29 ++++++++++++++++++++++++++---
>  1 file changed, 26 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index d8bb616..a8c19d5 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1077,6 +1077,7 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
>  	struct perf_probe_point *pp = &pev->point;
>  	char *ptr, *tmp;
>  	char c, nc = 0;
> +	bool file_spec = false;
>  	/*
>  	 * <Syntax>
>  	 * perf probe [EVENT=]SRC[:LN|;PTN]
> @@ -1105,6 +1106,23 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
>  		arg = tmp;
>  	}
>  
> +	/*
> +	 * Check arg is function or file name and copy it.
> +	 *
> +	 * We consider arg to be a file spec if and only if it satisfies
> +	 * all of the below criteria::
> +	 * - it does not include any of "+@%",
> +	 * - it includes one of ":;", and
> +	 * - it has a period '.' in the name.
> +	 *
> +	 * Otherwise, we consider arg to be a function specification.
> +	 */
> +	if (!strpbrk(arg, "+@%") && (ptr = strpbrk(arg, ";:")) != NULL) {
> +		/* This is a file spec if it includes a '.' before ; or : */
> +		if (memchr(arg, '.', ptr - arg))
> +			file_spec = true;
> +	}
> +
>  	ptr = strpbrk(arg, ";:+@%");
>  	if (ptr) {
>  		nc = *ptr;
> @@ -1115,10 +1133,9 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
>  	if (tmp == NULL)
>  		return -ENOMEM;
>  
> -	/* Check arg is function or file and copy it */
> -	if (strchr(tmp, '.'))	/* File */
> +	if (file_spec)
>  		pp->file = tmp;
> -	else			/* Function */
> +	else
>  		pp->function = tmp;
>  
>  	/* Parse other options */
> @@ -2265,6 +2282,9 @@ static int get_new_event_name(char *buf, size_t len, const char *base,
>  {
>  	int i, ret;
>  
> +	if (*base == '.')
> +		base++;
> +
>  	/* Try no suffix */
>  	ret = e_snprintf(buf, len, "%s", base);
>  	if (ret < 0) {
> @@ -2751,6 +2771,9 @@ int del_perf_probe_events(struct strlist *dellist)
>  			event = str;
>  		}
>  
> +		if (event && *event == '.')
> +			event++;
> +
>  		ret = e_snprintf(buf, 128, "%s:%s", group, event);
>  		if (ret < 0) {
>  			pr_err("Failed to copy event.");
> -- 
> 2.3.5
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