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

On 2020-01-17, Matthew Wilcox [off-list ref] wrote:

On Fri, Jan 03, 2020 at 08:29:27AM -0800, Sargun Dhillon wrote:

quoted

+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/>