From: ebiederm@xmission.com (Eric W. Biederman)
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jiri Olsa <jolsa@redhat.com>,
acme@redhat.com, mingo@elte.hu, paulus@samba.org,
cjashfor@linux.vnet.ibm.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/9] perf: Add sysfs format attribute for pmu device
Date: Tue, 24 Jan 2012 11:40:28 -0800 [thread overview]
Message-ID: <m139b4khxv.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <1327418538.2446.61.camel@twins> (Peter Zijlstra's message of "Tue, 24 Jan 2012 16:22:18 +0100")
Peter Zijlstra <a.p.zijlstra@chello.nl> writes:
> On Mon, 2012-01-23 at 16:33 +0100, Jiri Olsa wrote:
>>
>> > > +static ssize_t perf_default_event_format(struct pmu *pmu, char *page)
>> > > +{
>> > > + ssize_t ret;
>> > > +
>> > > + ret = sprintf(page, "config config:0-63\n");
>> > > + ret += sprintf(page + ret, "config1 config1:0-63\n");
>> > > + ret += sprintf(page + ret, "config2 config2:0-63\n");
>> >
>> > This looks like abuse of sysfs. The rule is one value per file.
>> > When you start adding newlines I can't see how this format attribute can
>> > be considered one value.
>>
>> ops, missed that rule.. I think we can carry the syntax files
>> within perf, or have it builtin somehow.. or procfs? :) PeterZ?
>
> There's plenty of exceptions to this rule though and touching procfs is
> even less appreciated.
There may be exceptions but certainly not plenty of exceptions.
There is also a practical scaling problem. You have to be careful
with how big you make that value before you have problems.
Perhaps what you want is a directory with a bunch of sysfs attributes?
All I know is I see buffer overflows waiting to happen whenever I look
at the code snippet above.
Eric
next prev parent reply other threads:[~2012-01-24 19:38 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-15 15:30 [RFC 0/3] perf tool: Add new event group management Jiri Olsa
2011-12-15 15:30 ` [PATCH 1/3] perf, tool: Add parser generator for events parsing Jiri Olsa
2011-12-16 14:02 ` Peter Zijlstra
2011-12-16 14:03 ` Peter Zijlstra
2011-12-20 10:31 ` Jiri Olsa
2011-12-20 10:47 ` Peter Zijlstra
2011-12-20 11:30 ` Peter Zijlstra
2011-12-20 11:39 ` Peter Zijlstra
2011-12-21 16:16 ` new syntax for perf event Jiri Olsa
2012-01-05 9:17 ` Jiri Olsa
2012-01-05 14:10 ` Peter Zijlstra
2012-01-09 15:28 ` Jiri Olsa
2012-01-09 15:43 ` Peter Zijlstra
2012-01-16 12:31 ` [RFCv3 0/9] perf tool: parser generator for events parsing Jiri Olsa
2012-01-16 12:31 ` [PATCH 1/9] perf, tool: Make perf_evlist__splice_list_tail global Jiri Olsa
2012-01-16 12:31 ` [PATCH 2/9] perf, tool: Remove unused functions from debugfs object Jiri Olsa
2012-01-16 12:31 ` [PATCH 3/9] perf, tool: Add sysfs mountpoint interface Jiri Olsa
2012-01-16 12:31 ` [PATCH 4/9] perf, tool: Add bitmap_or function into bitmap object Jiri Olsa
2012-01-16 12:31 ` [PATCH 5/9] perf: Add sysfs format attribute for pmu device Jiri Olsa
2012-01-23 15:13 ` Eric W. Biederman
2012-01-23 15:33 ` Jiri Olsa
2012-01-24 15:22 ` Peter Zijlstra
2012-01-24 19:40 ` Eric W. Biederman [this message]
2012-01-25 8:54 ` Jiri Olsa
2012-01-26 16:26 ` Peter Zijlstra
2012-01-27 12:32 ` Jiri Olsa
2012-01-16 12:31 ` [PATCH 6/9] perf, tool: Add parser generator for events parsing Jiri Olsa
2012-01-24 16:02 ` Peter Zijlstra
2012-01-25 8:42 ` Jiri Olsa
2012-01-16 12:31 ` [PATCH 7/9] perf, tool: Add config options support for event parsing Jiri Olsa
2012-01-16 12:31 ` [PATCH 8/9] perf, tool: Add perf pmu object to access pmu format definition Jiri Olsa
2012-01-16 12:31 ` [PATCH 9/9] perf, tool: Add support to specify pmu style event Jiri Olsa
2012-01-24 15:22 ` [RFCv3 0/9] perf tool: parser generator for events parsing Peter Zijlstra
2012-01-24 16:26 ` Peter Zijlstra
2012-01-25 0:53 ` Greg KH
2012-01-25 10:49 ` Peter Zijlstra
2012-01-25 14:37 ` Jiri Olsa
2012-01-26 16:23 ` Peter Zijlstra
2012-01-26 16:27 ` Greg KH
2012-01-25 17:01 ` Greg KH
2012-01-27 14:34 ` [PATCHv4 " Jiri Olsa
2012-01-27 14:34 ` [PATCH 1/9] perf, tool: Make perf_evlist__splice_list_tail global Jiri Olsa
2012-02-07 19:31 ` [tip:perf/core] perf evlist: Make splice_list_tail method public tip-bot for Jiri Olsa
2012-01-27 14:34 ` [PATCH 2/9] perf, tool: Remove unused functions from debugfs object Jiri Olsa
2012-02-17 9:51 ` [tip:perf/core] perf tools: " tip-bot for Jiri Olsa
2012-01-27 14:34 ` [PATCH 3/9] perf, tool: Add sysfs mountpoint interface Jiri Olsa
2012-02-17 9:52 ` [tip:perf/core] perf tools: " tip-bot for Jiri Olsa
2012-01-27 14:34 ` [PATCH 4/9] perf, tool: Add bitmap_or function into bitmap object Jiri Olsa
2012-02-17 9:53 ` [tip:perf/core] perf tools: " tip-bot for Jiri Olsa
2012-01-27 14:34 ` [PATCH 5/9] perf: Adding sysfs group format attribute for pmu device Jiri Olsa
2012-01-27 21:08 ` Corey Ashford
2012-01-27 21:19 ` Peter Zijlstra
2012-02-01 0:47 ` Corey Ashford
2012-01-30 9:52 ` Jiri Olsa
2012-02-01 1:25 ` Corey Ashford
2012-02-01 13:13 ` Jiri Olsa
2012-02-01 14:18 ` Peter Zijlstra
2012-02-01 14:31 ` Jiri Olsa
2012-02-01 14:40 ` Peter Zijlstra
2012-02-01 13:36 ` Peter Zijlstra
2012-02-02 0:33 ` Corey Ashford
2012-01-27 14:34 ` [PATCH 6/9] perf, tool: Add parser generator for events parsing Jiri Olsa
2012-01-27 14:34 ` [PATCH 7/9] perf, tool: Add config options support for event parsing Jiri Olsa
2012-01-27 14:34 ` [PATCH 8/9] perf, tool: Add perf pmu object to access pmu format definition Jiri Olsa
2012-01-27 14:34 ` [PATCH 9/9] perf, tool: Add support to specify pmu style event Jiri Olsa
2012-02-13 13:13 ` [PATCHv4 0/9] perf tool: parser generator for events parsing Jiri Olsa
2012-02-14 16:28 ` Peter Zijlstra
2012-02-14 16:43 ` Peter Zijlstra
2012-02-14 20:20 ` Peter Zijlstra
2012-02-14 20:57 ` Peter Zijlstra
2012-02-14 21:03 ` Peter Zijlstra
2012-02-15 9:24 ` Jiri Olsa
2012-02-15 11:18 ` Peter Zijlstra
2012-02-15 13:32 ` Jiri Olsa
2012-02-15 13:39 ` Peter Zijlstra
2012-02-15 9:04 ` Jiri Olsa
2012-02-15 11:03 ` Peter Zijlstra
2011-12-22 19:32 ` [PATCH 1/3] perf, tool: Add " Vince Weaver
2011-12-19 14:37 ` Jiri Olsa
2011-12-20 10:29 ` [PATCHv2 0/2] perf tool: " Jiri Olsa
2011-12-20 10:29 ` [PATCHv2 1/2] perf, tool: Add " Jiri Olsa
2011-12-20 10:29 ` [PATCHv2 2/2] perf, tool: Add more automated tests for event parsing Jiri Olsa
2011-12-20 17:37 ` [PATCH 1/3] perf, tool: Add parser generator for events parsing Arnaldo Carvalho de Melo
2011-12-21 9:55 ` Jiri Olsa
2011-12-15 15:30 ` [PATCH 2/3] perf, tool: Add new event group management Jiri Olsa
2011-12-20 17:47 ` Arnaldo Carvalho de Melo
2011-12-20 21:20 ` Peter Zijlstra
2011-12-21 11:54 ` Arnaldo Carvalho de Melo
2011-12-15 15:30 ` [PATCH 3/3] perf, tool: Add more automated tests for event parsing Jiri Olsa
2011-12-20 17:38 ` Arnaldo Carvalho de Melo
2011-12-21 8:47 ` [tip:perf/core] perf test: " tip-bot for Jiri Olsa
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