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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 937B1C4450A for ; Tue, 14 Jul 2026 12:59:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=3LmDNA6n/wCEDx/4MyjN30bZMYHbGggBnQ4KmGwZnlo=; b=rWGSV1fW+YzYMJddMx5cB8RTIl WjO4zYV5TUk3bEI9PmrfXMSdTb3sgr9A4O/26egb+vGNYtard9W0EXg17ejRUIxKUVvkm5qz+xd08 Aw6GP6v51ut4EGZCmo0U2DfgD8oYgwzZBNN8gQoI8d1m9FYp6rBbxzWpvxtiVGLIiGt0kpBQGEWvm 4J3V1oWq6rd8M7axU0w2biwwuYTklGacwKcFbVcknODUIsGnAuiKMnxq9BsPL4i4L7rNwVCKS2fiW F4B1qCu3xDQ3DdZjyFxlc72TZoAvhncyfxkXdvonyvztOdXRO4ACQu8Z5aeBgCQkPyyBNCJp4/VN3 TJSh2D+w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wjcjN-0000000C3NR-3Qbz; Tue, 14 Jul 2026 12:59:25 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wjcir-0000000C2k2-0HYA for linux-arm-kernel@lists.infradead.org; Tue, 14 Jul 2026 12:58:53 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 7B096601EC; Tue, 14 Jul 2026 12:58:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E4641F01558; Tue, 14 Jul 2026 12:58:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784033932; bh=3LmDNA6n/wCEDx/4MyjN30bZMYHbGggBnQ4KmGwZnlo=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=dF12FFJwKAiZFOaMtFvPtKhWr+aYeTKRlsw8xEsL9I5qldKsqghWC1XwHwKHC0wSD JPno6CSXl+kWg0mwee4nWBRZb7EugBQxI8q8Hrfne/TCCr35XKGY+gTLywexnkIhxm u/dYt3iEtXxzSgTmfU0LrQnws2oJpBe3VT5pRmAx6Db9M2eRRwC3exvhaDlSvcHYDt 6mb35FHo0iR/Vi23bxytD/MX3yiF+OlLsEHV4ryhAv0MdMYkEx80i/U1LZn7oHi6ns 7VBHPttQWhVyuwte79LNbu/XFhhsY/mUaGqBbw2RNZcYDx0OGVnryCqIzSFlKFWd1G SSVp2bVhfFyVg== From: Sudeep Holla Date: Tue, 14 Jul 2026 13:56:34 +0100 Subject: [PATCH v6 15/16] firmware: arm_scmi: Fix SCMI device destroy lifetimes MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260714-scmi_core_fixes-v6-15-3afe499d46e3@kernel.org> References: <20260714-scmi_core_fixes-v6-0-3afe499d46e3@kernel.org> In-Reply-To: <20260714-scmi_core_fixes-v6-0-3afe499d46e3@kernel.org> To: arm-scmi@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Cristian Marussi X-Mailer: b4 0.15.2 X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org scmi_child_dev_find() drops the reference returned by device_find_child() before returning the scmi_device pointer. A concurrent unregister can then release the device while the destroy path is still using the returned pointer. Make the lookup helper return the device_find_child() reference and keep it until scmi_device_destroy() has finished unregistering the child. Also split device_unregister() in __scmi_device_destroy() so the SCMI bus ID is not made reusable until after device_del() has removed the old scmi_dev.N name from sysfs. This avoids a new SCMI device reusing the same ID while the old device is still registered. The final device release callback is also a possible cleanup path when SCMI children are deleted by driver core recursion rather than __scmi_device_destroy(). Release the SCMI bus ID from a common helper used by destroy, register-failure and final-release paths, and clear scmi_dev->id after freeing it so the final release cannot free the same ID again. Fixes: 9ca67840c0dd ("firmware: arm_scmi: Balance device refcount when destroying devices") Reported-by: Sashiko Signed-off-by: Sudeep Holla --- drivers/firmware/arm_scmi/bus.c | 39 +++++++++++++++++++++++---------------- 1 file changed, 23 insertions(+), 16 deletions(-) diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c index a14df82a9310..e1f66c08c81d 100644 --- a/drivers/firmware/arm_scmi/bus.c +++ b/drivers/firmware/arm_scmi/bus.c @@ -237,8 +237,9 @@ static int scmi_match_by_id_table(struct device *dev, const void *data) return scmi_dev_match_by_id_table(scmi_dev, id_table); } -static struct scmi_device *scmi_child_dev_find(struct device *parent, - int prot_id, const char *name) +/* Returns a device_find_child() reference which must be dropped by caller. */ +static struct scmi_device * +scmi_child_dev_find_get(struct device *parent, int prot_id, const char *name) { struct scmi_device_id id_table[2] = { 0 }; struct device *dev; @@ -250,9 +251,6 @@ static struct scmi_device *scmi_child_dev_find(struct device *parent, if (!dev) return NULL; - /* Drop the refcnt bumped implicitly by device_find_child */ - put_device(dev); - return to_scmi_dev(dev); } @@ -390,17 +388,22 @@ void scmi_driver_unregister(struct scmi_driver *driver) } EXPORT_SYMBOL_GPL(scmi_driver_unregister); -static void scmi_device_release_syspower(struct scmi_device *scmi_dev) +static void scmi_device_release_resources(struct scmi_device *scmi_dev) { if (scmi_dev->protocol_id == SCMI_PROTOCOL_SYSTEM) cmpxchg(&scmi_syspower_registered, scmi_dev, NULL); + + if (scmi_dev->id) { + ida_free(&scmi_bus_id, scmi_dev->id); + scmi_dev->id = 0; + } } static void scmi_device_release(struct device *dev) { struct scmi_device *scmi_dev = to_scmi_dev(dev); - scmi_device_release_syspower(scmi_dev); + scmi_device_release_resources(scmi_dev); of_node_put(dev->of_node); kfree_const(scmi_dev->name); kfree(scmi_dev); @@ -413,9 +416,9 @@ static void __scmi_device_destroy(struct scmi_device *scmi_dev) dev_name(&scmi_dev->dev), scmi_dev->protocol_id, scmi_dev->name); - scmi_device_release_syspower(scmi_dev); - ida_free(&scmi_bus_id, scmi_dev->id); - device_unregister(&scmi_dev->dev); + device_del(&scmi_dev->dev); + scmi_device_release_resources(scmi_dev); + put_device(&scmi_dev->dev); } static struct scmi_device * @@ -433,9 +436,11 @@ __scmi_device_create(struct device_node *np, struct device *parent, * each DT defined protocol at probe time, and the concurrent * registration of SCMI drivers. */ - scmi_dev = scmi_child_dev_find(parent, protocol, name); - if (scmi_dev) + scmi_dev = scmi_child_dev_find_get(parent, protocol, name); + if (scmi_dev) { + put_device(&scmi_dev->dev); return scmi_dev; + } scmi_dev = kzalloc_obj(*scmi_dev); if (!scmi_dev) @@ -479,13 +484,13 @@ __scmi_device_create(struct device_node *np, struct device *parent, return scmi_dev; put_dev: + scmi_device_release_resources(scmi_dev); put_device(&scmi_dev->dev); - ida_free(&scmi_bus_id, id); return NULL; free_name: kfree_const(scmi_dev->name); free_dev: - scmi_device_release_syspower(scmi_dev); + scmi_device_release_resources(scmi_dev); kfree(scmi_dev); return NULL; } @@ -567,9 +572,11 @@ void scmi_device_destroy(struct device *parent, int protocol, const char *name) { struct scmi_device *scmi_dev; - scmi_dev = scmi_child_dev_find(parent, protocol, name); - if (scmi_dev) + scmi_dev = scmi_child_dev_find_get(parent, protocol, name); + if (scmi_dev) { __scmi_device_destroy(scmi_dev); + put_device(&scmi_dev->dev); + } } EXPORT_SYMBOL_GPL(scmi_device_destroy); -- 2.43.0