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Date:   Sat, 18 Jan 2020 10:14:48 +1100
From:   Aleksa Sarai <cyphar@cyphar.com>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Sargun Dhillon <sargun@sargun.me>, linux-kernel@vger.kernel.org,
        containers@lists.linux-foundation.org, linux-api@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, tycho@tycho.ws, jannh@google.com,
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        viro@zeniv.linux.org.uk, gpascutto@mozilla.com,
        ealvarez@mozilla.com, fweimer@redhat.com, jld@mozilla.com,
        arnd@arndb.de
Subject: Re: [PATCH v8 2/3] pid: Introduce pidfd_getfd syscall
Message-ID: <20200117231448.btck3qzepvtz5lcp@yavin>
References: <20200103162928.5271-1-sargun@sargun.me>
 <20200103162928.5271-3-sargun@sargun.me>
 <20200117230602.GA31944@bombadil.infradead.org>
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On 2020-01-17, Matthew Wilcox <willy@infradead.org> wrote:
> On Fri, Jan 03, 2020 at 08:29:27AM -0800, Sargun Dhillon wrote:
> > +SYSCALL_DEFINE3(pidfd_getfd, int, pidfd, int, fd,
> > +		unsigned int, flags)
> > +{
> > +	struct pid *pid;
> > +	struct fd f;
> > +	int ret;
> > +
> > +	/* flags is currently unused - make sure it's unset */
> > +	if (flags)
> > +		return -EINVAL;
>=20
> Is EINVAL the right errno here?  Often we use ENOSYS for bad flags to
> syscalls.

I don't think that's right -- every syscall I've seen gives you -EINVAL
for invalid flags (not to mention -ENOSYS would mean userspace would be
confused as to whether the syscall is actually supported by the kernel).

--=20
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>

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