From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5BBAEC77B7A for ; Wed, 31 May 2023 07:50:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234800AbjEaHtn (ORCPT ); Wed, 31 May 2023 03:49:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53220 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234784AbjEaHtR (ORCPT ); Wed, 31 May 2023 03:49:17 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D61AAA0 for ; Wed, 31 May 2023 00:48:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685519319; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=lN0vUYVvRFjvHRoECulLsT+QfP7ftEVA/sIPfwf8rQA=; b=Z5iG+cl85+VEXCz4FJ1VwvqMoad6lgET/0Jz5Pk+klyHk/C465J/zN0RLM2+P6XvplXuHR wArS+1wAQphEUeVyi4ilI9F+7xdJmLLyIz5nXKugncTMeYya8ie4H6317D5qf4zZ/YSqFb vGcIbGhlTLqUzgjV/YHwgwdnHmtCPXY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-402-Q2H1UejbNMiemtkarHc2zQ-1; Wed, 31 May 2023 03:48:35 -0400 X-MC-Unique: Q2H1UejbNMiemtkarHc2zQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1F9C3858F0F; Wed, 31 May 2023 07:48:35 +0000 (UTC) Received: from localhost (ovpn-12-54.pek2.redhat.com [10.72.12.54]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4601B2166B25; Wed, 31 May 2023 07:48:33 +0000 (UTC) Date: Wed, 31 May 2023 15:48:30 +0800 From: Baoquan He To: Zhen Lei Cc: Eric Biederman , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Michael Holzheu , Andrew Morton Subject: Re: [PATCH 4/6] kexec: improve the readability of crash_shrink_memory() Message-ID: References: <20230527123439.772-1-thunder.leizhen@huawei.com> <20230527123439.772-5-thunder.leizhen@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230527123439.772-5-thunder.leizhen@huawei.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/27/23 at 08:34pm, Zhen Lei wrote: > The major adjustments are: > 1. end = start + new_size. > The 'end' here is not an accurate representation, because it is not the > new end of crashk_res, but the start of ram_res, difference 1. So > eliminate it and replace it with ram_res->start. > 2. Use 'ram_res->start' and 'ram_res->end' as arguments to > crash_free_reserved_phys_range() to indicate that the memory covered by > 'ram_res' is released from the crashk. And keep it close to > insert_resource(). > 3. Replace 'if (start == end)' with 'if (!new_size)', clear indication that > all crashk memory will be shrunken. > > No functional change. > > Signed-off-by: Zhen Lei LGTM, Acked-by: Baoquan He > --- > kernel/kexec_core.c | 15 +++++---------- > 1 file changed, 5 insertions(+), 10 deletions(-) > > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > index bcc86a250ab3bf9..69fe92141b0b62d 100644 > --- a/kernel/kexec_core.c > +++ b/kernel/kexec_core.c > @@ -1108,7 +1108,6 @@ ssize_t crash_get_memory_size(void) > int crash_shrink_memory(unsigned long new_size) > { > int ret = 0; > - unsigned long start, end; > unsigned long old_size; > struct resource *ram_res; > > @@ -1119,9 +1118,7 @@ int crash_shrink_memory(unsigned long new_size) > ret = -ENOENT; > goto unlock; > } > - start = crashk_res.start; > - end = crashk_res.end; > - old_size = (end == 0) ? 0 : end - start + 1; > + old_size = !crashk_res.end ? 0 : resource_size(&crashk_res); > new_size = roundup(new_size, KEXEC_CRASH_MEM_ALIGN); > if (new_size >= old_size) { > ret = (new_size == old_size) ? 0 : -EINVAL; > @@ -1134,22 +1131,20 @@ int crash_shrink_memory(unsigned long new_size) > goto unlock; > } > > - end = start + new_size; > - crash_free_reserved_phys_range(end, crashk_res.end); > - > - ram_res->start = end; > + ram_res->start = crashk_res.start + new_size; > ram_res->end = crashk_res.end; > ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM; > ram_res->name = "System RAM"; > > - if (start == end) { > + if (!new_size) { > release_resource(&crashk_res); > crashk_res.start = 0; > crashk_res.end = 0; > } else { > - crashk_res.end = end - 1; > + crashk_res.end = ram_res->start - 1; > } > > + crash_free_reserved_phys_range(ram_res->start, ram_res->end); > insert_resource(&iomem_resource, ram_res); > > unlock: > -- > 2.25.1 >