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

From	Johannes Berg <johannes@sipsolutions.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH RFC v3 1/6] exterr: Introduce extended syscall error reporting
Date	2015-09-15 19:10 +0200
Message-ID	<q91TY-2GF-13@gated-at.bofh.it> (permalink)
References	(2 earlier) <q8Ioh-8kx-3@gated-at.bofh.it> <q8Zfr-7ex-13@gated-at.bofh.it> <q8ZyP-7BR-55@gated-at.bofh.it> <q90lb-mc-7@gated-at.bofh.it> <q91qW-1Tn-25@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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> I think that anything other than the errno "grab it now or lose it"
> behavior will prove confusing.  I don't think there is any other way to
> know that a given error report corresponds to a specific system call.
> Library calls can mess it up.  Kernel changes adding extended reporting to
> new system calls can mess it up.  Applications cannot possibly be expected
> to know which system calls might change the error-reporting status, they
> *have* to assume all of them will.
> 

Yeah I was about to say something similar - an application that expects
a certain syscall to have extended errors will get confused if running
on an older kernel where that syscall in fact does *not* have extended
errors (and thus also doesn't clear extended errors) and therefore the
extended error from a previous syscall could still be lingering on (for
example because the application didn't care to fetch it for that previo
us syscall.)

johannes
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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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