linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=m139b4khxv.fsf@fess.ebiederm.org \
    --to=ebiederm@xmission.com \
    --cc=a.p.zijlstra@chello.nl \
    --cc=acme@redhat.com \
    --cc=cjashfor@linux.vnet.ibm.com \
    --cc=jolsa@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@elte.hu \
    --cc=paulus@samba.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).