From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793211522; b=BlDJHO7z7iK4SlXSdPxX8Lx5qc9HoxIgnUxDcRkUaM4k2t16SMiXYuVp6owXW10JApqt 6jf75kEtIRslt9GvEKpehmO1Tv3xk95Tj9lo6mAvqVbCgO2R1WDmBWFP2i2eo/MzOZuGT pZd29x92a7Icyzsp3ziySp0l+LT2NUpwRVr22J1eAwW2xtwZUdOnqFlzK5LLi7QYqFDvU AYk+kALa0Z+ceR17tYmADsJ92ZJswKFxYV1e4GK0pi/0RoSUA+k/VNuchDOJkXBZv9B4d MYTtuftGLJwqWdMsriw14167B5VdUkcJCaKQOXptPts6msHpOw1V3qBXpJ2sOBhP9zA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793211522; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=5pP99jXXM8c63mYdseTcadOhP73EDMDe/gpeIFskLR4=; b=aPtftOjRQxWojhSoatmgQPT8hL8tlKK2FaKIhLclCHD1Emz3boL8dPT4pebYBBap6nz6 7MFpD8L8K9671+kbDs4rq/4k0WS/YRCFJlAMHheOxhhQO3FKf39i05tZ3pk2K3pftWNYE oUsKHdDxsPCpcLq/kSocfMOVNMqannr4pr6UB0R9nkrUAejVsQi2GRf4yGluMcXzp93qY h5uAxW9/nQfuYufMy38r0IAqIiGheqTOTTYSAB9ahmt/naIBlTsdf0rPFeU9BEUK6STZA SBmno0GmjGddLYAhj0mh9hoiyMBvk1qSajKPZ3j23gN5tRAWVQXjO41mBTfFM6VvABw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=jJIMMREG; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B22EE606A31C; Wed, 28 Oct 2026 18:18:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=jJIMMREG Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0BB211F01825; Wed, 28 Oct 2026 18:18:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793211521; bh=5pP99jXXM8c63mYdseTcadOhP73EDMDe/gpeIFskLR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jJIMMREGRQ9LQaVCp/xFvBVEqnfIvZWYjhTlCs+HCBpRnDfvL2D8fLOErOunINqJA BsbDuTsUcPD5huJG07i+NLrIL0X5WmO+caQu1iGBIb3T5Eq5a+FwRzRK2o1B5kQbRI JwIk4to2eKo0MRIUtYyCigy8NMVGxbDxr5rv+zfw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tomas Winkler , Alexander Usyskin , Zhang Xiaoxu , Miquel Raynal Subject: [PATCH 5.15 405/571] mtd: Clean refcounting with MTD_PARTITIONED_MASTER Date: Wed, 28 Oct 2026 17:59:12 +0100 Message-ID: <20261028170017.621276350@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Miquel Raynal commit 264725e35fbc3b67e053a405e022393a6017e6da upstream. The logic is way too convoluted, let's clean the kref_get/put section to clarify what this block does when using CONFIG_MTD_PARTITIONED_MASTER: - Iterate through all the parent mtd devices - Grab a reference over them all but the master - Only grab the master whith CONFIG_MTD_PARTITIONED_MASTER Same logic must apply in the put path, otherwise it would be broken. Cc: Tomas Winkler Cc: Alexander Usyskin Cc: Zhang Xiaoxu Fixes: 19bfa9ebebb5 ("mtd: use refcount to prevent corruption") Signed-off-by: Miquel Raynal Tested-by: Alexander Usyskin Link: https://lore.kernel.org/linux-mtd/20230731090903.770277-1-miquel.raynal@bootlin.com Signed-off-by: Greg Kroah-Hartman --- drivers/mtd/mtdcore.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -1175,14 +1175,15 @@ int __get_mtd_device(struct mtd_info *mt return -ENODEV; } - kref_get(&mtd->refcnt); - - while (mtd->parent) { - if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) || mtd->parent != master) - kref_get(&mtd->parent->refcnt); + while (mtd) { + if (mtd != master) + kref_get(&mtd->refcnt); mtd = mtd->parent; } + if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER)) + kref_get(&master->refcnt); + return 0; } EXPORT_SYMBOL_GPL(__get_mtd_device); @@ -1238,10 +1239,12 @@ void __put_mtd_device(struct mtd_info *m { struct mtd_info *master = mtd_get_master(mtd); - while (mtd != master) { + while (mtd) { + /* kref_put() can relese mtd, so keep a reference mtd->parent */ struct mtd_info *parent = mtd->parent; - kref_put(&mtd->refcnt, mtd_device_release); + if (mtd != master) + kref_put(&mtd->refcnt, mtd_device_release); mtd = parent; }