From nobody Sun Feb 8 17:36:25 2026 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 69473EB64D8 for ; Tue, 20 Jun 2023 13:23:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233037AbjFTNXO (ORCPT ); Tue, 20 Jun 2023 09:23:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231329AbjFTNWy (ORCPT ); Tue, 20 Jun 2023 09:22:54 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26E201BC0 for ; Tue, 20 Jun 2023 06:22:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1687267328; x=1718803328; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=ioFas3xTWzb8p1vfOgeqS8+ZIZhYvxBAQPoT1srDwhE=; b=nOnClQV/m7RrmLVcfehPfOf5h5q2TnkgefqZxaS4N8dlRbNDQlE71mmS shEGREAy4VcGL4DNtCRB3CBKJf7290afzhyv5DjUhIJinoIwxxn8myqM2 IlKwcI/I2WiRkQZRJMtjZllevgsadzs6ewzhymTFbeFEO6Ea7J5Wn/qxd mJAFngqHSb4v+SuaHvzX4MN91o1pbzGXlC14mNwWsjgH8qGeun9bDsY3k s1p7AvmBra70Cb380PZ1MPv6bHGOuA5JUzu8dox/v+pZGPRgLmEoRfrLh 4IHidO+1OzESyVqfyvbS/nD7radZEcEn5EPDZCRFGV/rrs6321u2hlMSA g==; X-IronPort-AV: E=McAfee;i="6600,9927,10747"; a="349588298" X-IronPort-AV: E=Sophos;i="6.00,257,1681196400"; d="scan'208";a="349588298" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jun 2023 06:20:07 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10747"; a="691427007" X-IronPort-AV: E=Sophos;i="6.00,257,1681196400"; d="scan'208";a="691427007" Received: from sannilnx-dsk.jer.intel.com ([10.12.231.107]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jun 2023 06:20:04 -0700 From: Alexander Usyskin To: Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Tomas Winkler , Alexander Usyskin , Vitaly Lubart , Andy Shevchenko Subject: [PATCH 2/2] mtd: call external _get and _put in right order Date: Tue, 20 Jun 2023 16:19:05 +0300 Message-Id: <20230620131905.648089-3-alexander.usyskin@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230620131905.648089-1-alexander.usyskin@intel.com> References: <20230620131905.648089-1-alexander.usyskin@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" MTD provider provides mtd_info object to mtd subsystem. With kref patch the mtd_info object can be alive after provider released mtd device. Fix calling order in _get and _put functions to allow mtd provider to safely alloc and release mtd object. Execute: 1) call external _get 2) get_module 3) add internal kref in the get function and opposite order in the put one. The _put_device callback should be the last in put as the master struct memory may be freed in this callback. Signed-off-by: Alexander Usyskin --- drivers/mtd/mtdcore.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 84bd1878367d..a5bc60013edf 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -1227,21 +1227,20 @@ int __get_mtd_device(struct mtd_info *mtd) struct mtd_info *master =3D mtd_get_master(mtd); int err; =20 - if (!try_module_get(master->owner)) - return -ENODEV; - - kref_get(&mtd->refcnt); - if (master->_get_device) { err =3D master->_get_device(mtd); - - if (err) { - kref_put(&mtd->refcnt, mtd_device_release); - module_put(master->owner); + if (err) return err; - } } =20 + if (!try_module_get(master->owner)) { + if (master->_put_device) + master->_put_device(master); + return -ENODEV; + } + + kref_get(&mtd->refcnt); + while (mtd->parent) { if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) || mtd->parent !=3D master) kref_get(&mtd->parent->refcnt); @@ -1338,13 +1337,14 @@ void __put_mtd_device(struct mtd_info *mtd) mtd =3D parent; } =20 - if (master->_put_device) - master->_put_device(master); + if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER)) + kref_put(&master->refcnt, mtd_device_release); =20 module_put(master->owner); =20 - if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER)) - kref_put(&master->refcnt, mtd_device_release); + /* must be the last as master can be freed in the _put_device */ + if (master->_put_device) + master->_put_device(master); } EXPORT_SYMBOL_GPL(__put_mtd_device); =20 --=20 2.34.1