From nobody Tue Oct 7 05:33:22 2025 Received: from cstnet.cn (smtp81.cstnet.cn [159.226.251.81]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2C37610A1E; Mon, 14 Jul 2025 09:20:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.81 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752484832; cv=none; b=KqlA07g6ao5YJ28XE8U81zolTCn/p6PgOBlkbKwn3qeRPFplpU6k8YRcgmby//SbNQnAlVfjGP77xQeywciIEtxtdjyxjyMxhD1X1vGh5XTkCmNHxyXJuTPlYKkNRhTy5HbMDBul28bLxS6/6uVxlfwc1VWe1bk/g9U3L/vBark= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752484832; c=relaxed/simple; bh=L7BcJGw5ym6qPfgaTER92wS3T7ZHpzuHID6PqQyX3Gc=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=KiIiWc37y0pUBU6mc2W5ee7Kh1pdoTzHKYYkutgqI9m2sKIUAB66YpFh/zRr290IWa0RHwdCW+jjxB6Vqt126ZV5TpubWjcpeOcxH5miOO09dlyG0q2aYzIgHhZieS73T2R76w08IJHbRQMs+01v9eTbAlupTN050J8Wjh7mLWg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.81 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from icess-ProLiant-DL380-Gen10.. (unknown [211.71.28.34]) by APP-03 (Coremail) with SMTP id rQCowAD3h3kTy3RotjvpAw--.2702S2; Mon, 14 Jul 2025 17:17:10 +0800 (CST) From: Ma Ke To: dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, rrichter@amd.com, ming.li@zohomail.com, zijun.hu@oss.qualcomm.com, fabio.m.de.francesco@linux.intel.com Cc: linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, Ma Ke , stable@vger.kernel.org Subject: [PATCH] cxl/region: Balance device refcount when destroying devices Date: Mon, 14 Jul 2025 17:16:54 +0800 Message-Id: <20250714091654.3206432-1-make24@iscas.ac.cn> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: rQCowAD3h3kTy3RotjvpAw--.2702S2 X-Coremail-Antispam: 1UD129KBjvJXoWxJF18Kr1fXF4kZr4DZF4fXwb_yoW8GrWkp3 yUCFWUuryrCF109rnxZayUZry5uFWDuayrurW8J34Fg3s5J3y0yrWUA3Z0gF17A392qF1U ZrnFyF18CayUW3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPj14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAac4AC62xK8xCEY4vEwIxC4wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC 0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr0_Gr 1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IE rcIFxwACI402YVCY1x02628vn2kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCY02Avz4vE14 v_GFWl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AK xVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrx kI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v2 6r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8Jw CI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUYPEfUUUU U X-CM-SenderInfo: ppdnvj2u6l2u1dvotugofq/ Content-Type: text/plain; charset="utf-8" Using device_find_child() to lookup the proper device to destroy causes an unbalance in device refcount, since device_find_child() calls an implicit get_device() to increment the device's reference count before returning the pointer. cxl_port_find_switch_decoder() directly converts this pointer to a cxl_decoder and returns it without releasing the reference properly. We should call put_device() to decrement reference count. As comment of device_find_child() says, 'NOTE: you will need to drop the reference with put_device() after use'. Found by code review. Cc: stable@vger.kernel.org Fixes: d6879d8cfb81 ("cxl/region: Add function to find a port's switch deco= der by range") Signed-off-by: Ma Ke --- drivers/cxl/core/region.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 6e5e1460068d..cae16d761261 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -3234,6 +3234,9 @@ cxl_port_find_switch_decoder(struct cxl_port *port, s= truct range *hpa) struct device *cxld_dev =3D device_find_child(&port->dev, hpa, match_decoder_by_range); =20 + /* Drop the refcnt bumped implicitly by device_find_child */ + put_device(cxld_dev); + return cxld_dev ? to_cxl_decoder(cxld_dev) : NULL; } =20 --=20 2.25.1