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 A77D5C05021 for ; Fri, 10 Nov 2023 17:54:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230169AbjKJRyV (ORCPT ); Fri, 10 Nov 2023 12:54:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230119AbjKJRxT (ORCPT ); Fri, 10 Nov 2023 12:53:19 -0500 Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E77742C22; Fri, 10 Nov 2023 09:01:27 -0800 (PST) Received: by mail.gandi.net (Postfix) with ESMTPA id C14F360005; Fri, 10 Nov 2023 17:01:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1699635686; 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; bh=xEm3o8VU+39ALGHyQKeorPBmsousXOC90k2SfHr6l+8=; b=akEddODtZEANlh32ZjSuOqfH9OK2OytJ70Ew/Ly8Ab5NURRRE4ozxB0zfFCHCcZ7wuloAO 5XVpuDCbWUHw41I5C0TYDWV1e/cTXvG8jxDVqUMuEBnePr96w8Vrm5bMLAwhVooARZ/vEd rDfqqXPNDLxEXcaLHDkmJf+4mCesbVL1xmEx+jc2ZRBU1E7a8k6yMtJi9qnJuSGXi7jOL4 ka3EMTDWJGjasU4jtE03UiaQWb0hAma7qFqL6OLBWSP5DWPcScArcPnSuNCdobgYVrklqG 43PH6RASlV6flnurH5hzK7/5gk9GL1hseswLHho4YDPcDpD6wU573tpPfxpC4g== From: Herve Codina To: Greg Kroah-Hartman , "Rafael J. Wysocki" , Saravana Kannan , Geert Uytterhoeven Cc: linux-kernel@vger.kernel.org, Allan Nielsen , Horatiu Vultur , Steen Hegelund , Thomas Petazzoni , Herve Codina , stable@vger.kernel.org Subject: [PATCH 1/1] driver core: Avoid using fwnode in __fwnode_link_del() Date: Fri, 10 Nov 2023 18:01:20 +0100 Message-ID: <20231110170121.769221-1-herve.codina@bootlin.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-GND-Sasl: herve.codina@bootlin.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A refcount issue can appeared in __fwnode_link_del() due to the pr_debug() call: WARNING: CPU: 0 PID: 901 at lib/refcount.c:25 refcount_warn_saturate+0xe5/0x110 Call Trace: ? refcount_warn_saturate+0xe5/0x110 ? __warn+0x81/0x130 ? refcount_warn_saturate+0xe5/0x110 ? report_bug+0x191/0x1c0 ? srso_alias_return_thunk+0x5/0x7f ? prb_read_valid+0x1b/0x30 ? handle_bug+0x3c/0x80 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? refcount_warn_saturate+0xe5/0x110 kobject_get+0x68/0x70 of_node_get+0x1e/0x30 of_fwnode_get+0x28/0x40 fwnode_full_name_string+0x34/0x90 fwnode_string+0xdb/0x140 vsnprintf+0x17b/0x630 va_format.isra.0+0x71/0x130 vsnprintf+0x17b/0x630 vprintk_store+0x162/0x4d0 ? srso_alias_return_thunk+0x5/0x7f ? srso_alias_return_thunk+0x5/0x7f ? srso_alias_return_thunk+0x5/0x7f ? try_to_wake_up+0x9c/0x620 ? rwsem_mark_wake+0x1b2/0x310 vprintk_emit+0xe4/0x2b0 _printk+0x5c/0x80 __dynamic_pr_debug+0x131/0x160 ? srso_alias_return_thunk+0x5/0x7f __fwnode_link_del+0x25/0xa0 fwnode_links_purge+0x39/0xb0 of_node_release+0xd9/0x180 kobject_put+0x7b/0x190 ... Indeed, an of_node is destroyed and so, of_node_release() is called because the of_node refcount reached 0. of_node_release() calls fwnode_links_purge() to purge the links and ended with __fwnode_link_del() calls. __fwnode_link_del calls pr_debug() to print the fwnodes (of_nodes) involved in the link and so this call is done while one of them is no more available (ie the one related to the of_node_release() call) Remove the pr_debug() call to avoid the use of the links fwnode while destroying the fwnode itself. Fixes: ebd6823af378 ("driver core: Add debug logs when fwnode links are added/deleted") Cc: stable@vger.kernel.org Signed-off-by: Herve Codina --- drivers/base/core.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index f4b09691998e..62088c663014 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -109,8 +109,6 @@ int fwnode_link_add(struct fwnode_handle *con, struct fwnode_handle *sup) */ static void __fwnode_link_del(struct fwnode_link *link) { - pr_debug("%pfwf Dropping the fwnode link to %pfwf\n", - link->consumer, link->supplier); list_del(&link->s_hook); list_del(&link->c_hook); kfree(link); -- 2.41.0