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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B847DC432C1 for ; Tue, 24 Sep 2019 09:09:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8AC6820872 for ; Tue, 24 Sep 2019 09:09:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="D1W13TV9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2504103AbfIXJJo (ORCPT ); Tue, 24 Sep 2019 05:09:44 -0400 Received: from frisell.zx2c4.com ([192.95.5.64]:49451 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2504086AbfIXJJo (ORCPT ); Tue, 24 Sep 2019 05:09:44 -0400 Received: by frisell.zx2c4.com (ZX2C4 Mail Server) with ESMTP id dc158a12; Tue, 24 Sep 2019 08:24:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=zx2c4.com; h=from:to:cc :subject:date:message-id:mime-version:content-transfer-encoding; s=mail; bh=u6Qv1urxbVN4KEZOHZSn+suLjNY=; b=D1W13TV9yrrZcXg5+xUO TLD65mmdS+8GAmgtxbY2A3svs4a1lbwwbqqbTb+SluV7MLQF+PQTT9hyY2BI7ua3 3SZ9r9FNPo86bpuI9/hbAvOdjAVVrYRfQMTFc2gQfodNHMyJGNRERb7ylDkY69A3 ghtvyBZyzaEyGBlkiuOL3QNqQIlbyaTAXKd0LA/bYuwG9UrBXkRQnw4riMTcfPOt wQtdTDKKyuWprgOLfrFQSlD/Lk43LoBPpYK8mPkfWDLXDt7nfPSj3lGOXR939n48 bf2xpTAU5F6BYTH+nrcNCRf9nHv0qUfAbrFLUaKp4///x9OvHmRwyREP+8LbBlPK +w== Received: by frisell.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 3b8a643f (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256:NO); Tue, 24 Sep 2019 08:24:06 +0000 (UTC) From: "Jason A. Donenfeld" To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Jason A. Donenfeld" Subject: [PATCH] net: print proper warning on dst underflow Date: Tue, 24 Sep 2019 11:09:37 +0200 Message-Id: <20190924090937.13001-1-Jason@zx2c4.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Proper warnings with stack traces make it much easier to figure out what's doing the double free and create more meaningful bug reports from users. Signed-off-by: Jason A. Donenfeld --- net/core/dst.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/core/dst.c b/net/core/dst.c index 1325316d9eab..193af526e908 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -172,7 +172,7 @@ void dst_release(struct dst_entry *dst) int newrefcnt; newrefcnt = atomic_dec_return(&dst->__refcnt); - if (unlikely(newrefcnt < 0)) + if (WARN_ONCE(newrefcnt < 0, "dst_release underflow")) net_warn_ratelimited("%s: dst:%p refcnt:%d\n", __func__, dst, newrefcnt); if (!newrefcnt) @@ -187,7 +187,7 @@ void dst_release_immediate(struct dst_entry *dst) int newrefcnt; newrefcnt = atomic_dec_return(&dst->__refcnt); - if (unlikely(newrefcnt < 0)) + if (WARN_ONCE(newrefcnt < 0, "dst_release_immediate underflow")) net_warn_ratelimited("%s: dst:%p refcnt:%d\n", __func__, dst, newrefcnt); if (!newrefcnt) -- 2.21.0