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 EB5633624A5; Sat, 12 Sep 2026 10:01:47 +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=1789207309; cv=none; b=fbyOnGFYoJtFCn93iF5TQPnuqPbES93AzNGmJow9oyVM4ubBB7ZCGWqfYmeR5lsuRs3kiGg6jblgPK6jhCF1R5PHVWssYTPMXEM+/mSn3v53Qm4HiOOqZb7YVFygn1lGiAkrChQ3mglz5iBy5k+JniEuJCWIPaMWwuPiXswe8us= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789207309; c=relaxed/simple; bh=iEJ3GxaTgse/Ky1r1/xrs4g7tVnWEJzfte7pi2hlbps=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=j6WHCgx1Nhp1eA/vX8gRXl+TDd+wpVxsgtnC0hvsJeHTrvzkUWJTHTPhTEMaUvfJHRwB6zLQ+/N++aiFFS4x5WYgHGH/MsokSfSPgdbT/rvDsqkAJvR4DavCt0lQtWM6GwftL3JdkgN9HBVqna4uNmxapQxsqFzUv9mz9E23GIw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ttN3T2mu; 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="ttN3T2mu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A47901F000FF; Sat, 12 Sep 2026 10:01:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789207307; bh=U/mPFnkC69srbgUuV5OzsG5wqc0hj5bz4QonE4xY9X0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ttN3T2muc199+mgT3+/B2dw+5e0VeB3lF+66H7m0CoY641JRNkt5lRYN/hUzyYE1v RO9/SlL40v5/Giq/ONHt+mKf+sHG6c7udgReS2YbQ+u3b0r1yiR5IhRHlZ3aQuulL/ yPOcwPofEgUM7E26o3YZoixP1ZQ5LZtSSXX0aJrE= 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 0386/1518] firmware: arm_scmi: Drop handle on protocol bind failures Date: Sat, 12 Sep 2026 08:42:35 +0200 Message-ID: <20260912065632.192707843@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065623.398859879@linuxfoundation.org> References: <20260912065623.398859879@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 e3a5c30d233ca5d3e799a80da806554c703bda13 ] The SCMI bus notifier acquires an SCMI handle when the driver core emits BUS_NOTIFY_BIND_DRIVER, before invoking the protocol driver probe callback. The protocol probe path only checks whether sdev->handle is set. If device_link_add() fails after the handle has been acquired, the protocol device can still bind with a valid handle but without the dependency link to the SCMI parent. A concurrent parent unbind can then miss the child and tear down the SCMI instance while the child still holds a handle into it. If the protocol driver probe later fails, for example with -EPROBE_DEFER, the driver core emits BUS_NOTIFY_DRIVER_NOT_BOUND rather than BUS_NOTIFY_UNBOUND_DRIVER. The SCMI notifier only released the handle on BUS_NOTIFY_UNBOUND_DRIVER, so each failed protocol-device bind leaked the SCMI instance users refcount and left sdev->handle set after the failed probe. Make the link helper report failure and drop the acquired handle if the link cannot be created. Also handle BUS_NOTIFY_DRIVER_NOT_BOUND in the same cleanup path used for unbind so failed probes balance the earlier BUS_NOTIFY_BIND_DRIVER acquisition. Fixes: 971fc0665f13 ("firmware: arm_scmi: Move handle get/set helpers") Reported-by: Sashiko Link: https://patch.msgid.link/20260714-scmi_core_fixes-v6-10-3afe499d46e3@kernel.org Signed-off-by: Sudeep Holla Signed-off-by: Sasha Levin --- drivers/firmware/arm_scmi/driver.c | 31 ++++++++++++++++++++++-------- 1 file changed, 23 insertions(+), 8 deletions(-) diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index a84765b7405bf..55f14953f2ebd 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -2541,21 +2541,31 @@ static int scmi_handle_put(const struct scmi_handle *handle) return 0; } -static void scmi_device_link_add(struct device *consumer, +static bool scmi_device_link_add(struct device *consumer, struct device *supplier) { struct device_link *link; link = device_link_add(consumer, supplier, DL_FLAG_AUTOREMOVE_CONSUMER); - WARN_ON(!link); + return !WARN_ON(!link); +} + +static void scmi_clear_handle(struct scmi_device *scmi_dev) +{ + if (!scmi_dev->handle) + return; + + scmi_handle_put(scmi_dev->handle); + scmi_dev->handle = NULL; } static void scmi_set_handle(struct scmi_device *scmi_dev) { scmi_dev->handle = scmi_handle_get(&scmi_dev->dev); - if (scmi_dev->handle) - scmi_device_link_add(&scmi_dev->dev, scmi_dev->handle->dev); + if (scmi_dev->handle && + !scmi_device_link_add(&scmi_dev->dev, scmi_dev->handle->dev)) + scmi_clear_handle(scmi_dev); } static int __scmi_xfer_info_init(struct scmi_info *sinfo, @@ -2838,6 +2848,7 @@ static int scmi_bus_notifier(struct notifier_block *nb, { struct scmi_info *info = bus_nb_to_scmi_info(nb); struct scmi_device *sdev = to_scmi_dev(data); + const char *status; /* Skip devices of different SCMI instances */ if (sdev->dev.parent != info->dev) @@ -2847,18 +2858,22 @@ static int scmi_bus_notifier(struct notifier_block *nb, case BUS_NOTIFY_BIND_DRIVER: /* setup handle now as the transport is ready */ scmi_set_handle(sdev); + status = "about to be BOUND."; + break; + case BUS_NOTIFY_DRIVER_NOT_BOUND: + scmi_clear_handle(sdev); + status = "NOT BOUND."; break; case BUS_NOTIFY_UNBOUND_DRIVER: - scmi_handle_put(sdev->handle); - sdev->handle = NULL; + scmi_clear_handle(sdev); + status = "UNBOUND."; break; default: return NOTIFY_DONE; } dev_dbg(info->dev, "Device %s (%s) is now %s\n", dev_name(&sdev->dev), - sdev->name, action == BUS_NOTIFY_BIND_DRIVER ? - "about to be BOUND." : "UNBOUND."); + sdev->name, status); return NOTIFY_OK; } -- 2.53.0