Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error reporting

From	Alexander Shishkin <alexander.shishkin@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error reporting
Date	2015-09-15 17:30 +0200
Message-ID	<q90lb-mc-7@gated-at.bofh.it> (permalink)
References	<q7z3I-6Aq-7@gated-at.bofh.it> <q7z3I-6Aq-19@gated-at.bofh.it> <q8Ioh-8kx-3@gated-at.bofh.it> <q8Zfr-7ex-13@gated-at.bofh.it> <q8ZyP-7BR-55@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Johannes Berg <johannes@sipsolutions.net> writes:

> On Tue, 2015-09-15 at 17:15 +0300, Alexander Shishkin wrote:
>> 
>> > It seems to me that current->ext_err_code needs to be cleared on 
>> > each system call entry (except for your special prctl() of 
>> > course!).
>> 
>> I'd say, it should be up to the program to decide for how long they 
>> want to keep the extended error code around.
>> 
>
> I'm not convinced that works - imagine a library wanting to use the
> prctl(), but the main application isn't doing that. Should the library
> clear it before every call, to be sure it's not getting stale data?
> etc.

In other words, a syscall that's capable of throwing an extended error
does clear the current::ext_err_code every time, but not other
syscalls. Otherwise it will indeed get very confusing.

Regards,
--
Alex
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Thread

[PATCH RFC v3 0/6] Introduce extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-09-11 18:10 +0200
  [PATCH RFC v3 1/6] exterr: Introduce extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-09-11 18:10 +0200
    Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error  reporting Jonathan Corbet <corbet@lwn.net> - 2015-09-14 22:20 +0200
      Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-09-15 16:20 +0200
        Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error  reporting Johannes Berg <johannes@sipsolutions.net> - 2015-09-15 16:40 +0200
          Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-09-15 17:30 +0200
            Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error  reporting Jonathan Corbet <corbet@lwn.net> - 2015-09-15 18:40 +0200
              Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error  reporting Johannes Berg <johannes@sipsolutions.net> - 2015-09-15 19:10 +0200
    Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error  reporting Jonathan Corbet <corbet@lwn.net> - 2015-09-15 00:00 +0200
  [PATCH RFC v3 6/6] perf tools: Use extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-09-11 18:10 +0200
  [PATCH RFC v3 2/6] perf: Use extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-09-11 18:10 +0200

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