From patchwork Fri Jan 28 19:56:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Waiman Long X-Patchwork-Id: 12729012 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B020CC433FE for ; Fri, 28 Jan 2022 19:57:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 16AF66B00FE; Fri, 28 Jan 2022 14:57:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 119DE6B0102; Fri, 28 Jan 2022 14:57:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EFCA06B0106; Fri, 28 Jan 2022 14:57:30 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0170.hostedemail.com [216.40.44.170]) by kanga.kvack.org (Postfix) with ESMTP id DD7BC6B00FE for ; Fri, 28 Jan 2022 14:57:30 -0500 (EST) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 9D61118209A93 for ; Fri, 28 Jan 2022 19:57:30 +0000 (UTC) X-FDA: 79080755460.19.B40EDED Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf16.hostedemail.com (Postfix) with ESMTP id 3E816180002 for ; Fri, 28 Jan 2022 19:57:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1643399849; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=z7PkS3p7o3c1KlQT9mE47JFulyDrby+E1xl/snWb8i0=; b=ZmdZqs0qj1/Nqe1eOgebpdN7IIG08owjDtRMU0p6RzzEj3zqsHl0ZJYgokLJLTUx5QLAHa djCL3agpOZ5JGXg5FfHgkFw9ZGR6sd1qEeanYtnvyTpnquVThnBu0ojENNWZwZohprABjY wVfaluFUYc00bq6QlAdud4l8nV+TG8g= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-463-iCC205RvNbe_8lZYT7eujw-1; Fri, 28 Jan 2022 14:57:26 -0500 X-MC-Unique: iCC205RvNbe_8lZYT7eujw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C9FE31083F6D; Fri, 28 Jan 2022 19:57:24 +0000 (UTC) Received: from llong.com (unknown [10.22.33.1]) by smtp.corp.redhat.com (Postfix) with ESMTP id D155C5DB82; Fri, 28 Jan 2022 19:57:23 +0000 (UTC) From: Waiman Long To: Johannes Weiner , Michal Hocko , Vladimir Davydov , Andrew Morton Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Rafael Aquini , Waiman Long Subject: [PATCH 1/2] mm/page_owner: Introduce SNPRINTF() macro that includes length error check Date: Fri, 28 Jan 2022 14:56:41 -0500 Message-Id: <20220128195642.416743-2-longman@redhat.com> In-Reply-To: <20220128195642.416743-1-longman@redhat.com> References: <20220128195642.416743-1-longman@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Stat-Signature: rou6kyitf3npesmno3tzodbhhy4smc78 X-Rspam-User: nil Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=ZmdZqs0q; spf=none (imf16.hostedemail.com: domain of longman@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=longman@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3E816180002 X-HE-Tag: 1643399850-71403 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In print_page_owner(), there is a repetitive check after each snprintf() to make sure that the final length is less than the buffer size. Simplify the code and make it easier to read by embedding the buffer length check and increment inside the macro. Signed-off-by: Waiman Long --- mm/page_owner.c | 50 +++++++++++++++++++++++-------------------------- 1 file changed, 23 insertions(+), 27 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index 99e360df9465..c52ce9d6bc3b 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -325,12 +325,20 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m, seq_putc(m, '\n'); } +#define SNPRINTF(_buf, _size, _len, _err, _fmt, ...) \ + do { \ + _len += snprintf(_buf + _len, _size - _len, _fmt, \ + ##__VA_ARGS__); \ + if (_len >= _size) \ + goto _err; \ + } while (0) + static ssize_t print_page_owner(char __user *buf, size_t count, unsigned long pfn, struct page *page, struct page_owner *page_owner, depot_stack_handle_t handle) { - int ret, pageblock_mt, page_mt; + int ret = 0, pageblock_mt, page_mt; char *kbuf; count = min_t(size_t, count, PAGE_SIZE); @@ -338,44 +346,32 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, if (!kbuf) return -ENOMEM; - ret = snprintf(kbuf, count, - "Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_ts %llu ns\n", - page_owner->order, page_owner->gfp_mask, - &page_owner->gfp_mask, page_owner->pid, - page_owner->ts_nsec, page_owner->free_ts_nsec); - - if (ret >= count) - goto err; + SNPRINTF(kbuf, count, ret, err, + "Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_ts %llu ns\n", + page_owner->order, page_owner->gfp_mask, + &page_owner->gfp_mask, page_owner->pid, + page_owner->ts_nsec, page_owner->free_ts_nsec); /* Print information relevant to grouping pages by mobility */ pageblock_mt = get_pageblock_migratetype(page); page_mt = gfp_migratetype(page_owner->gfp_mask); - ret += snprintf(kbuf + ret, count - ret, - "PFN %lu type %s Block %lu type %s Flags %pGp\n", - pfn, - migratetype_names[page_mt], - pfn >> pageblock_order, - migratetype_names[pageblock_mt], - &page->flags); - - if (ret >= count) - goto err; + SNPRINTF(kbuf, count, ret, err, + "PFN %lu type %s Block %lu type %s Flags %pGp\n", + pfn, migratetype_names[page_mt], + pfn >> pageblock_order, + migratetype_names[pageblock_mt], + &page->flags); ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0); if (ret >= count) goto err; - if (page_owner->last_migrate_reason != -1) { - ret += snprintf(kbuf + ret, count - ret, + if (page_owner->last_migrate_reason != -1) + SNPRINTF(kbuf, count, ret, err, "Page has been migrated, last migrate reason: %s\n", migrate_reason_names[page_owner->last_migrate_reason]); - if (ret >= count) - goto err; - } - ret += snprintf(kbuf + ret, count - ret, "\n"); - if (ret >= count) - goto err; + SNPRINTF(kbuf, count, ret, err, "\n"); if (copy_to_user(buf, kbuf, ret)) ret = -EFAULT;