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 9767E36165F for ; Wed, 1 Jul 2026 16:53:20 +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=1782924801; cv=none; b=DTtiwrYN4marpszU/r+trxgfpZlgjC3vNXh1gAlL4VT/FIzXRzQMzXug6UON/tkJc0rtZ8dNj38zccBCAI6nIJcpQNbdSmjhs83mrZUcVKj4+zFFxLFrtD5Lb355Z3kS6Ro7xj3KIK9MDA+7DWZ4nKSR9fOIR8EGVcLMfv8IOCo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782924801; c=relaxed/simple; bh=wix0Xh1YQutzSBWTyKn7+sahuxEeGpjwiQBOQw/nlfc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Af6jky6KaOZ84oLi8hbE9h1NIyrOyn+HJvFRZykJHXMIYfKQOiem0IBEKQXTkWBGW52PV+ia1/C98xR+pfX92VZrGA8ZoqtpW7/amLe3dlr/F0tBskDLj7BGAJiguuWCTtEBMYso5oDN5B/JJaT8pNiEgQXFq6cCkpG57pDRKNk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G7NSELVW; 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="G7NSELVW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDBAB1F00A3A; Wed, 1 Jul 2026 16:53:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782924800; bh=WI8N45gPmQ8iJjB+GBzTf6cfCJJQqV/EJ7frAbCwTn0=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=G7NSELVWGhn1RRD/UspFPix48SEfW9DsnTHHdzwPeUCzJlyqr5ysZ2XwiNC/g9yjM WH0TRv2ATNPdmReEyfwYqsFBxM64UNnNzkqG+QmoeI91rZk7Yira2gApWhQ9Opmr7E dMpCHmiMT7kWhuklMVrGGZ8pw4RIB9B193qtG6myEVk729TU6cVRI/Me0A/WwvgBrD EKyZEF7TpIb7Dad0flVx/xIzEepVldt+3n/DAcNajIDhHCL2afAJKpodkw+Hv1nEK2 QJ9nZmzzG46EpQEBNR0AhTO9T2Bn5xrq1FyP/zdV9bBzeDzmOaRVPbMxwrrrWjJG3T tpD+HpHhkSsmg== From: Sudeep Holla Date: Wed, 01 Jul 2026 17:52:25 +0100 Subject: [PATCH v2 04/14] 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: <20260701-scmi_core_fixes-v2-4-1f5e85553f73@kernel.org> References: <20260701-scmi_core_fixes-v2-0-1f5e85553f73@kernel.org> In-Reply-To: <20260701-scmi_core_fixes-v2-0-1f5e85553f73@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. Fixes: 46edb8d1322c ("firmware: arm_scmi: provide the mandatory device release callback") 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 | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c index d4beefa4234f..e1deb1b3011d 100644 --- a/drivers/firmware/arm_scmi/bus.c +++ b/drivers/firmware/arm_scmi/bus.c @@ -250,8 +250,9 @@ 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; @@ -263,9 +264,6 @@ 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); } @@ -422,8 +420,9 @@ static void __scmi_device_destroy(struct scmi_device *scmi_dev) if (scmi_dev->protocol_id == SCMI_PROTOCOL_SYSTEM) atomic_set(&scmi_syspower_registered, 0); + device_del(&scmi_dev->dev); ida_free(&scmi_bus_id, scmi_dev->id); - device_unregister(&scmi_dev->dev); + put_device(&scmi_dev->dev); } static struct scmi_device * @@ -440,9 +439,11 @@ __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; + } /* * Ignore any possible subsequent failures while creating the device @@ -492,8 +493,8 @@ __scmi_device_create(struct device_node *np, struct device *parent, return scmi_dev; put_dev: + ida_free(&scmi_bus_id, scmi_dev->id); put_device(&scmi_dev->dev); - ida_free(&scmi_bus_id, id); return NULL; } @@ -574,9 +575,11 @@ 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