From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754642Ab3LDIUR (ORCPT ); Wed, 4 Dec 2013 03:20:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:12881 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753735Ab3LDIUP (ORCPT ); Wed, 4 Dec 2013 03:20:15 -0500 Date: Wed, 4 Dec 2013 16:19:38 +0800 From: Baoquan He To: Vivek Goyal Cc: mjg59@srcf.ucam.org, greg@kroah.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, ebiederm@xmission.com, hpa@zytor.com Subject: Re: [PATCH 4/6] kexec: A new system call, kexec_file_load, for in kernel kexec Message-ID: <20131204081938.GE3298@localhost.localdomain> References: <1384969851-7251-1-git-send-email-vgoyal@redhat.com> <1384969851-7251-5-git-send-email-vgoyal@redhat.com> <20131204015657.GD3298@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131204015657.GD3298@localhost.localdomain> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/04/13 at 09:56am, Baoquan He wrote: > On 11/20/13 at 12:50pm, Vivek Goyal wrote: > > + * that kexec_mutex is held. > > + */ > > I think kexec_add_buffer is guaranteed to be called before allocating > control pages, why not updating image->control_page after each time > kexec_add_buffer is called. Then when control page is needed, effective > address in crash_kernel region can be given. This can be a little more > efficient. Check again, it's not a good idea. Because buf_align is different when kexec_add_buffer is called. Sometime the bug_align is larger than 4k. Please ignore this comment. > > > +int kexec_add_buffer(struct kimage *image, char *buffer, > > + unsigned long bufsz, unsigned long memsz, > > + unsigned long buf_align, unsigned long buf_min, > > + unsigned long buf_max, int top_down, unsigned long *load_addr) > > +{ > > + > > + unsigned long nr_segments = image->nr_segments, new_nr_segments; > > + struct kexec_segment *ksegment; > > + struct kexec_buf *kbuf; > > + > > + /* Currently adding segment this way is allowed only in file mode */ > > + if (!image->file_mode) > > + return -EINVAL; > > + > > + if (nr_segments >= KEXEC_SEGMENT_MAX) > > + return -EINVAL; > > + > > + /* > > + * Make sure we are not trying to add buffer after allocating > > + * control pages. All segments need to be placed first before > > + * any control pages are allocated. As control page allocation > > + * logic goes through list of segments to make sure there are > > + * no destination overlaps. > > + */ > > + WARN_ONCE(!list_empty(&image->control_pages), "Adding kexec buffer" > > + " after allocating control pages\n"); > > + > > + kbuf = kzalloc(sizeof(struct kexec_buf), GFP_KERNEL); > > + if (!kbuf) > > + return -ENOMEM; > > +