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 75F993DCDAC for ; Wed, 8 Jul 2026 09:00:39 +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=1783501241; cv=none; b=lIrq0CP4vEorXwjZYJCka/6M+OecIwq6UpPtakhHCFbK8jOp15KiXb0nSbym8/oXd6KdFoWEG+kZN202GQf9oZIEZo7dW7GEw1JV3ZXY9O6m25N7WIapbEzNYhq8DCc4YhV4LR9zfjDKeh5Y9WMJ2dh1KqUWontfxnvmIxs4Xms= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783501241; c=relaxed/simple; bh=kdKRkywuPTu45EEDZZPr3FBsixv1h/6Dw39RWsmiMZI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=bAhjrEc0bZ2o0vpeQGA/y5FXJ0XgyQakmq1MeqJUjDFmjWL88IwKeQZBhqEL5Ry30Rg0Z7a4Z8NREpDbDkD5qnnVQ+HfnZxT/8WxF65rmL4wOS+XIFLvm03lmoBbp1wD17F6pPk2gv6scqNX5qXw7qpPaFlglnHBAG5sM1fJKqI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PkOlbRxv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PkOlbRxv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB8E91F000E9; Wed, 8 Jul 2026 09:00:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783501239; bh=3LmDNA6n/wCEDx/4MyjN30bZMYHbGggBnQ4KmGwZnlo=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=PkOlbRxvYBy07ZQfhwTUPtOOyauaQURLx32jDAzDzQIt8wbtBl6pp7rUkbEpa87pu Dtbj2UnVfQp25A3c5ke3n8xPgB3kkiJ9BV6nm+3eia+5iBzzLrWbDD3suUA4kSqmP3 Hzwm+ipIGKaDLvCW6iVTjy82o588QuDibIsNSHkBDT6Jj5UoLWhbvBcRAutLgyiURr c8auVr5GPJ0ESEjwR43qh/JWazmB5UB3o0CpqIMX8ESasSABsdEtTPhUakmf7rE8E3 XFf+0rxPNaZ9lajywMnAM3nQWstobUyJEWoI3ecODMlVPBm3bV9i3hJDfLZV1B2MIX qmimIkoNUAmAQ== From: Sudeep Holla Date: Wed, 08 Jul 2026 10:00:11 +0100 Subject: [PATCH v4 15/16] firmware: arm_scmi: Fix SCMI device destroy lifetimes Precedence: bulk X-Mailing-List: arm-scmi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260708-scmi_core_fixes-v4-15-53142cd60b63@kernel.org> References: <20260708-scmi_core_fixes-v4-0-53142cd60b63@kernel.org> In-Reply-To: <20260708-scmi_core_fixes-v4-0-53142cd60b63@kernel.org> To: arm-scmi@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Cristian Marussi X-Mailer: b4 0.15.2 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