Re: [PATCH v8 2/3] pid: Introduce pidfd_getfd syscall

[Aleksa Sarai]

On 2020-01-17, Matthew Wilcox <willy@xxxxxxxxxxxxx> 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;
> 
> 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).

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

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