Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752171AbaFLStm (ORCPT ); Thu, 12 Jun 2014 14:49:42 -0400 Received: from mail-qa0-f51.google.com ([209.85.216.51]:57315 "EHLO mail-qa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751624AbaFLStj (ORCPT ); Thu, 12 Jun 2014 14:49:39 -0400 MIME-Version: 1.0 Reply-To: mtk.manpages@gmail.com In-Reply-To: <20140612180501.GB15795@redhat.com> References: <1398682853-7541-1-git-send-email-khandual@linux.vnet.ibm.com> <53625681.8010905@redhat.com> <53670F35.6010502@linux.vnet.ibm.com> <53725FF6.6060004@redhat.com> <537316DB.4060701@linux.vnet.ibm.com> <53734B7D.4010504@redhat.com> <53996A20.3030300@linux.vnet.ibm.com> <20140612180501.GB15795@redhat.com> From: "Michael Kerrisk (man-pages)" Date: Thu, 12 Jun 2014 20:49:18 +0200 Message-ID: Subject: Re: [PATCH v2] ptrace: Clarify PTRACE_GETREGSET/PTRACE_SETREGSET, documentation in uapi header To: Oleg Nesterov Cc: Anshuman Khandual , Pedro Alves , Peter Zijlstra , lkml , "H. Peter Anvin" , suresh.b.siddha@intel.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 12, 2014 at 8:05 PM, Oleg Nesterov wrote: > On 06/12, Anshuman Khandual wrote: >> >> > --- a/include/uapi/linux/ptrace.h >> > +++ b/include/uapi/linux/ptrace.h >> > @@ -39,12 +39,17 @@ >> > * payload are exactly the same layout. >> > * >> > * This interface usage is as follows: >> > - * struct iovec iov = { buf, len}; >> > + * struct iovec iov = { buf, len }; >> > * >> > * ret = ptrace(PTRACE_GETREGSET/PTRACE_SETREGSET, pid, NT_XXX_TYPE, &iov); >> > * >> > - * On the successful completion, iov.len will be updated by the kernel, >> > - * specifying how much the kernel has written/read to/from the user's iov.buf. >> > + * On entry, iov describes the buffer's address and length. The buffer's length >> > + * must be a multiple of the size of a single register in the register set. The >> > + * kernel never reads or writes more than iov.len, and caps the buffer length to >> > + * the register set's size. In other words, the kernel reads or writes >> > + * min(iov.len, regset size). > > I think this should be self-obvious ;) otherwise why do we need to pass > the length of the buffer? > > But of course I won't argue with the additional documentation, perhaps you > can re-send this patch to akpm? Usually ptrace changes are routed via -mm > tree. > > But if we update the kernel header, then probably it would be more important > to update the man-page. To me the description of GETREGSET looks good, but > probably it could also mention that buflen should be multiple of regsize (as > you did above). Add Michael. Can someone send a patch, then? Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/