From: Vince Weaver <vincent.weaver@maine.edu>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Dave Jones <davej@redhat.com>, trinity@vger.kernel.org
Subject: Re: [PATCH 1/2] Add an IGNORE_ENOSYS flag and use it
Date: Wed, 28 May 2014 11:38:36 -0400 (EDT) [thread overview]
Message-ID: <alpine.DEB.2.10.1405281134320.6109@vincent-weaver-1.umelst.maine.edu> (raw)
In-Reply-To: <1401247674.5468.2.camel@concordia>
On Wed, 28 May 2014, Michael Ellerman wrote:
> On Tue, 2014-05-27 at 01:02 -0400, Vince Weaver wrote:
> > On Tue, 27 May 2014, Michael Ellerman wrote:
> >
> > > On Mon, 2014-05-26 at 20:41 -0400, Dave Jones wrote:
> > > > On Mon, May 26, 2014 at 10:32:01PM +1000, Michael Ellerman wrote:
> > > > > Some syscalls return ENOSYS depending on their arguments. We don't want
> > > > > to stop calling them just because we hit one of those cases. Add a flag
> > > > > to specify this behaviour so we don't have to keep special-casing those
> > > > > calls in mkcall().
> > > >
> > > > I was hopeful this list wouldn't grow, but that doesn't seem to be
> > > > the case. Begrudgingly, I applied this. It's going to be a lot
> > > > cleaner to maintain if people keep doing this.
> > >
> > > Yeah it's annoying for sure, maybe perf will be the last one, but at least
> > > there's a clean way to handle it if not.
> >
> > As the author of the man page that you probably got the perf ENOSYS info
> > from, I have to put out there that perf_event_open() has really
> > inconsistent and confusing error return values, and they vary among the
> > various architectures.
>
> Actually I didn't read the man page, but thanks for reminding me that it
> exists. And yes I am aware of your dislike of the perf interface.
I had just recently contributed an improved "ERRORS" section to the
perf_event_open manpage that tries to be complete, but I'm sure I missed
some corner cases. It does document the odd choice of returning ENOSYS in
the PERF_SAMPLE_STACK_USER case.
It's a shame there isn't some sort of automated tool that could spit out
all possible system call return values, it would make it a lot easier to
keep things consistent.
Vince
prev parent reply other threads:[~2014-05-28 15:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-26 12:32 [PATCH 1/2] Add an IGNORE_ENOSYS flag and use it Michael Ellerman
2014-05-26 12:32 ` [PATCH 2/2] Mark perf_event_open() with IGNORE_ENOSYS Michael Ellerman
2014-05-27 0:41 ` [PATCH 1/2] Add an IGNORE_ENOSYS flag and use it Dave Jones
2014-05-27 1:05 ` Michael Ellerman
2014-05-27 5:02 ` Vince Weaver
2014-05-28 3:27 ` Michael Ellerman
2014-05-28 15:38 ` Vince Weaver [this message]
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