linux-kernel - Re: [BUG] perf probe segfaulting when asked for variable it doesn't find

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Date:	Thu, 29 May 2014 18:56:03 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Ingo Molnar <mingo@...hat.com>, Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] perf probe segfaulting when asked for variable it doesn't
 find

(2014/05/29 6:44), Arnaldo Carvalho de Melo wrote:
> Masami-san,
> 
> 	While trying:
> 
> [root@zoo ~]# perf probe 'vfs_getname=getname_flags:65 pathname=result->name:string'
> Failed to find the location of result at this address.
>  Perhaps, it has been optimized out.
> Failed to find 'result' in this function.
>   Error: Failed to add events. (-2)
> [root@zoo ~]# perf probe 'vfs_getname=getname_flags:65 pathname=result->name:string'
> Added new event:
> Segmentation fault (core dumped)
> 
> I got segfaulted while in the past I would get the much nicer:
> 
> [root@zoo ~]# perf probe 'vfs_getname=getname_flags:65 pathname=result->name:string'
> Failed to find the location of result at this address.
>  Perhaps, it has been optimized out.
> Failed to find 'result' in this function.
>   Error: Failed to add events. (-2)
> [root@zoo ~]#

Oops, I got that. Bad SEGV was reproduced here too.
And I've found an error-handling miss in the convert_variable(),
I'll send a patch for fixing it.
Thank you very much for bisecting and finding my fault.

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com


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