[PATCH v2 6/7] ptrace: introduce PTRACE_SET_SYSCALL_INFO request

[Oleg Nesterov]

On 01/16, Dmitry V. Levin wrote:
>
> The idea is to use "op" to specify the operation, and "flags" to specify
> future extensions to the operation.

OK,

> That is, the zero check implied by copy_struct_from_user() is not really
> needed here since the compatibility is tracked by "op" and "flags":

OK, but then why this patch uses copy_struct_from_user() ?

Why can't we simply do

	if (user_size != PTRACE_SYSCALL_INFO_SIZE_VER0)
		return -EINVAL;

	if (copy_from_user(..., user_size))
		return EFAULT;

now, until we add the extensions ?

Oleg.