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Date:   Thu, 6 Apr 2023 15:17:55 +0200
From:   Petr Vorel <pvorel@suse.cz>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Naresh Kamboju <naresh.kamboju@linaro.org>,
        open list <linux-kernel@vger.kernel.org>,
        LTP List <ltp@lists.linux.it>, llvm@lists.linux.dev,
        chrubis <chrubis@suse.cz>, Nathan Chancellor <nathan@kernel.org>,
        Anders Roxell <anders.roxell@linaro.org>,
        Daniel =?iso-8859-2?Q?D=EDaz?= <daniel.diaz@linaro.org>,
        Benjamin Copeland <ben.copeland@linaro.org>,
        Tudor Cretu <tudor.cretu@arm.com>
Subject: Re: LTP: list of failures on 32bit and compat mode
Message-ID: <20230406131755.GA1608262@pevik>
Reply-To: Petr Vorel <pvorel@suse.cz>
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> On Thu, Apr 6, 2023, at 14:48, Petr Vorel wrote:
> >> On Thu, Apr 6, 2023, at 12:56, Petr Vorel wrote:

> >> Ah, I see. This must be the padding code then, not the time64
> >> conversion:

> >> +int recvmmsg(int fd, struct mmsghdr *msgvec, unsigned int vlen, unsigned int flags, struct timespec *timeout)
> >> +{
> >> +#if LONG_MAX > INT_MAX
> >> +       struct mmsghdr *mh = msgvec;
> >> +       unsigned int i;
> >> +       for (i = vlen; i; i--, mh++)
> >> +               mh->msg_hdr.__pad1 = mh->msg_hdr.__pad2 = 0;
> >> +#endif

> > I suppose this is a suggestion for fix in LTP. I'd expect is should go into
> > testcases/kernel/syscalls/sendmmsg/sendmmsg_var.h into static inline int
> > sys_recvmmsg(...)

> > But that at least on glibc 64bit compilation does not see __pad1 member:

> > ../sendmmsg/sendmmsg_var.h: In function ‘sys_recvmmsg’:
> > ../sendmmsg/sendmmsg_var.h:47:28: error: ‘struct msghdr’ has no member 
> > named ‘__pad1’
> >    47 |                 mh->msg_hdr.__pad1 = mh->msg_hdr.__pad2 = 0;
> >       |                            ^

> Sorry, I should have been clearer, the snippet I cited is
> from the musl sources, and the __pad access is what causes the
> segfault. The fix is to catch the fault on ltp, same as for the
> time64 conversions.

Thanks! I've just searched in musl as well, because it didn't make sense to me
it'd be a code for LTP.

"to catch the fault on ltp" I wonder if it's not actually musl bug.

Kind regards,
Petr


>       Arnd