From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0DE8C4FB9BA; Tue, 13 Oct 2026 12:23:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791894194; cv=none; b=a2tP2zxl0xA1uncdxsCxxl2I1nvkmt/XVr/tGRmxiiALmGbc2qU/0sjO77uBZ9W2Z38qZ1ifMzbCR6lJs7W89NEFvgYRgwVDeNT0wEuFaZjEZp660WApREq5tJawBHigoZRRtSCVo7bTNi8darbfkaILW+HzbmuJ9r+nshnbZss= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791894194; c=relaxed/simple; bh=e4yijun1v4+RcAUJkTASIPCznc/JFjG92ADpT5DfDKw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kAZCnFmOA6YpoiNjZ7LuBMeioyDgLW6kUhB147ssAA2QUq4OLy2R+WcK0F1Vxqgbg7/pxIF1Vv/8OmKoSibdSecN7xtQTJhmVhdfYpOqCUg3JSufBEFjRjfuk7kNxgWAxkolsMcj9GsvHphDMkUntg80yF2RuIfHZbhnW98rjBU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aM+HDUR7; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="aM+HDUR7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 64FF81F000FF; Tue, 13 Oct 2026 12:23:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791894192; bh=TVm3jdv7fgF8UONPZbe/BVE5Vuu5pwq+RXfHGZiEBt8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=aM+HDUR70w1qitLEjmTo3VwzauzeO8fq2XOK4FOsJYCPMFIo0qY9wbDSk3za+mtl/ udUl6Yvf9SdZw98WwWwDz/X5Qfvd+43Zmnez2INFfPxE2ZB9YGpJyxeilmG8Ugea9f y8qfI6DrRx9DWbGY2EcNPKCFmULwE0AEFjNEyxNs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , Sudeep Holla , Sasha Levin Subject: [PATCH 6.18 476/621] firmware: arm_scmi: Fix SCMI device destroy lifetimes Date: Tue, 13 Oct 2026 13:37:51 +0200 Message-ID: <20261013112932.130457466@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112920.855194808@linuxfoundation.org> References: <20261013112920.855194808@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sudeep Holla [ Upstream commit 6abe8fe36b29ff51d1a42c2f338972883f4751a5 ] 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 Link: https://patch.msgid.link/20260714-scmi_core_fixes-v6-15-3afe499d46e3@kernel.org Signed-off-by: Sudeep Holla Signed-off-by: Sasha Levin --- 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 169fbcba7c3cb..1115e8398668e 100644 --- a/drivers/firmware/arm_scmi/bus.c +++ b/drivers/firmware/arm_scmi/bus.c @@ -258,8 +258,9 @@ static int scmi_match_by_id_table(struct device *dev, const void *data) return __scmi_dev_match_by_id_table(scmi_dev, id_table, false); } -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; @@ -271,9 +272,6 @@ 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); } @@ -415,17 +413,22 @@ 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); @@ -438,9 +441,9 @@ 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 * @@ -458,9 +461,11 @@ __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) @@ -504,13 +509,13 @@ __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; } @@ -592,9 +597,11 @@ 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); -- 2.53.0