Re: [PATCH] [BZ #19402] Clear list of acquired robust mutexes in the child process after forking.

[Torvald Riegel <triegel at redhat dot com>]

On Mon, 2017-01-23 at 15:57 +0100, Florian Weimer wrote:
> On 01/13/2017 04:37 PM, Torvald Riegel wrote:
> > On Fri, 2017-01-13 at 14:11 +0100, Florian Weimer wrote:
> >> On 12/23/2016 10:31 PM, Torvald Riegel wrote:
> >>>> Can we add a test case for this?
> >>> What do you have in mind?  Checking that the list is reset to zero after
> >>> fork?  Do we need a test for that if we have documented the need to do
> >>> that in the code?
> >>
> >> What about the attached patch?
> >
> > That looks fine generally, with the following exceptions / comments:
> >
> > According to the feedback so far we got for
> > http://austingroupbugs.net/view.php?id=1112 the trylock-based test is
> > actually UB.  There should be a comment making that clear (ie, that we
> > rely on something we know about our current implementation to test
> > this).
> >
> > If this was a multi-threaded test program, it would be invalid because
> > non-async-signal-safe functions are executed in the child before exec()
> > is called.  In a single-threaded program, it's not quite clear to me
> > what POSIX really wants.  There's indication that only AS-safe functions
> > should be called, but IIRC that's not explicitly stated.
> > Florian says we still need to support this as an extension.  If so, this
> > should be made clear in the test (using a suitable comment).
> 
> I added a comment and an additional test which uses an error-checking mutex.
> 
> Test case still passes on current master.  Okay to commit?

LGTM.