From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vitaly Mayatskikh Subject: Re: [PATCH 1/2] Introduce check_readable_bytes() Date: Thu, 14 May 2009 19:57:46 +0200 Message-ID: <87iqk3zhwl.wl%vmayatsk@redhat.com> References: <1242317939-15392-1-git-send-email-v.mayatskih@gmail.com> <1242317939-15392-2-git-send-email-v.mayatskih@gmail.com> <20090514173858.GA10059@dhcp231-156.rdu.redhat.com> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Cc: Vitaly Mayatskikh , sandeen@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Josef Bacik Return-path: Received: from fg-out-1718.google.com ([72.14.220.155]:37315 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751592AbZENR5s (ORCPT ); Thu, 14 May 2009 13:57:48 -0400 In-Reply-To: <20090514173858.GA10059@dhcp231-156.rdu.redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: At Thu, 14 May 2009 13:40:09 -0400, Josef Bacik wrote: > > + volatile char c; > > + int ret = 0; > > + long page_begin = (unsigned long)uaddr & PAGE_MASK; > > + long page_end = ((unsigned long)uaddr + size) & PAGE_MASK; > > + long ptr = page_begin; > > + > > Firstly page_begin/page_end/ptr should all be unsigned long. Secondly page_end > should be uaddr+size-1. > > > + if (unlikely(size == 0)) > > + goto out; > > + > > + while (!ret && ptr <= page_end) { > > + ret = __get_user(c, (const char __user*)ptr); > > + if (!ret) > > + ptr += PAGE_SIZE; > > + } > > + > > + if (likely(!ret)) > > + ret = size; > > + else > > + ret = (ptr == page_begin) ? > > + -EFAULT : (const char __user *)ptr - uaddr; > > This isn't quite right either, we do some pointer math, and return that and its > casted as an int? That seems like a bad idea in general. Thanks, Did you like the approach in general? -- wbr, Vitaly