Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758505Ab3EOJfe (ORCPT ); Wed, 15 May 2013 05:35:34 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:56762 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754985Ab3EOJfd convert rfc822-to-8bit (ORCPT ); Wed, 15 May 2013 05:35:33 -0400 X-IronPort-AV: E=Sophos;i="4.87,677,1363104000"; d="scan'208";a="7275575" Message-ID: <5193564F.9090408@cn.fujitsu.com> Date: Wed, 15 May 2013 17:33:03 +0800 From: Zhang Yanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.8) Gecko/20121012 Thunderbird/10.0.8 MIME-Version: 1.0 To: HATAYAMA Daisuke CC: vgoyal@redhat.com, ebiederm@xmission.com, akpm@linux-foundation.org, cpw@sgi.com, kumagai-atsushi@mxc.nes.nec.co.jp, lisa.mitchell@hp.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, jingbai.ma@hp.com, linux-mm@kvack.org, riel@redhat.com, walken@google.com, hughd@google.com, kosaki.motohiro@jp.fujitsu.com Subject: Re: [PATCH v6 1/8] vmcore: clean up read_vmcore() References: <20130515090507.28109.28956.stgit@localhost6.localdomain6> <20130515090545.28109.86085.stgit@localhost6.localdomain6> In-Reply-To: <20130515090545.28109.86085.stgit@localhost6.localdomain6> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/05/15 17:34:14, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/05/15 17:34:16 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3653 Lines: 133 于 2013年05月15日 17:05, HATAYAMA Daisuke 写道: > Rewrite part of read_vmcore() that reads objects in vmcore_list in the > same way as part reading ELF headers, by which some duplicated and > redundant codes are removed. > > Signed-off-by: HATAYAMA Daisuke > Acked-by: Vivek Goyal This cleanup really makes the code more clear. Just one minor nitpick below. Acked-by: Zhang Yanfei > --- > > fs/proc/vmcore.c | 68 ++++++++++++++++-------------------------------------- > 1 files changed, 20 insertions(+), 48 deletions(-) > > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c > index 17f7e08..ab0c92e 100644 > --- a/fs/proc/vmcore.c > +++ b/fs/proc/vmcore.c > @@ -118,27 +118,6 @@ static ssize_t read_from_oldmem(char *buf, size_t count, > return read; > } > > -/* Maps vmcore file offset to respective physical address in memroy. */ > -static u64 map_offset_to_paddr(loff_t offset, struct list_head *vc_list, > - struct vmcore **m_ptr) > -{ > - struct vmcore *m; > - u64 paddr; > - > - list_for_each_entry(m, vc_list, list) { > - u64 start, end; > - start = m->offset; > - end = m->offset + m->size - 1; > - if (offset >= start && offset <= end) { > - paddr = m->paddr + offset - start; > - *m_ptr = m; > - return paddr; > - } > - } > - *m_ptr = NULL; > - return 0; > -} > - > /* Read from the ELF header and then the crash dump. On error, negative value is > * returned otherwise number of bytes read are returned. > */ > @@ -147,8 +126,8 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer, > { > ssize_t acc = 0, tmp; > size_t tsz; > - u64 start, nr_bytes; > - struct vmcore *curr_m = NULL; > + u64 start; > + struct vmcore *m = NULL; > > if (buflen == 0 || *fpos >= vmcore_size) > return 0; > @@ -174,33 +153,26 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer, > return acc; > } > > - start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m); > - if (!curr_m) > - return -EINVAL; > - > - while (buflen) { > - tsz = min_t(size_t, buflen, PAGE_SIZE - (start & ~PAGE_MASK)); > - > - /* Calculate left bytes in current memory segment. */ > - nr_bytes = (curr_m->size - (start - curr_m->paddr)); > - if (tsz > nr_bytes) > - tsz = nr_bytes; > - > - tmp = read_from_oldmem(buffer, tsz, &start, 1); > - if (tmp < 0) > - return tmp; > - buflen -= tsz; > - *fpos += tsz; > - buffer += tsz; > - acc += tsz; > - if (start >= (curr_m->paddr + curr_m->size)) { > - if (curr_m->list.next == &vmcore_list) > - return acc; /*EOF*/ > - curr_m = list_entry(curr_m->list.next, > - struct vmcore, list); > - start = curr_m->paddr; > + list_for_each_entry(m, &vmcore_list, list) { > + if (*fpos < m->offset + m->size) { > + tsz = m->offset + m->size - *fpos; > + if (buflen < tsz) > + tsz = buflen; if (tsz > buflen) tsz = buflen; seems better. Or you can use a min_t here: tsz = min_t(size_t, m->offset + m->size - *fpos, buflen); > + start = m->paddr + *fpos - m->offset; > + tmp = read_from_oldmem(buffer, tsz, &start, 1); > + if (tmp < 0) > + return tmp; > + buflen -= tsz; > + *fpos += tsz; > + buffer += tsz; > + acc += tsz; > + > + /* leave now if filled buffer already */ > + if (buflen == 0) > + return acc; > } > } > + > return acc; > } > > > -- 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/