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 4604F327204 for ; Fri, 3 Jul 2026 20:25:43 +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=1783110344; cv=none; b=j/OF+P75RTIx3BC5EJsOyOu9Z2vcVGx1xk9u4gTPCt/R+HIck71dlYp1LrSWDD8NaJQu7FcEDVmI2yEHC/VNpgLKc0hia4K8chNYFbaKwBXO1gazfSedJFStUaoC3AF+n+NpiyXMG4td4yC1emZICuo+dWZE3aPmoQ832Jlv/y8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783110344; c=relaxed/simple; bh=VKOm3RmEotS4H8obge4/fdT99EPuFlgaLbg0CJKBKVg=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=DDWvCkEu1tIvYYu4gEuKZZGDvHoAbWGVDEFm/R1ldLvkJLGQN153+XV72UH7E1DNy+lwyEABB8AkSXbVl+5yEo9BPjHHdtezZZLtPxI+HTh5hIWn4MgyYBFoncYByKzP5m2GDNYlN5ZsKFLy75llss2HnWHdT6+zLV7zKN97SK8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AmREA9lr; 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="AmREA9lr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E8DA1F00AC4; Fri, 3 Jul 2026 20:25:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783110343; bh=u5DWrWPIxkt1f50GIPXLPv4ckLJWFETJKFnIXi7eobc=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=AmREA9lrL8acgoKfB3Z4dziNTBYstfyG9klAEvUIbK3pwQXYcnujVfc6um8qhx6ED B2ndvLT3mbbK5Qt+91znzNSQmxmqCecBoTLwHRnxqsr2b3XU4Iqehuj7Z7rQTfDpWu RO9vvDqfR8HWRCYZDXfkkkagKtMYurElCUWgb5yC8byRwQePDaZ3Bo4rqQG1b0nTjZ KU0BhTEldois77kVvMZjyss/px+IKqTrHxgLSorfp3Fx0G86+MaNN8wUbaoFqdYybe p1n37Aaz4bY7J4aQJwSEJWROe6EkOHRISuwzUCGlDopHRE7rntKccXLu2RJ6mSvtK6 mz2gzll7LtXlw== From: Sudeep Holla Date: Fri, 03 Jul 2026 21:22:52 +0100 Subject: [PATCH v3 16/17] firmware: arm_scmi: Drop handle on protocol bind failures 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: <20260703-scmi_core_fixes-v3-16-5bae9766abfc@kernel.org> References: <20260703-scmi_core_fixes-v3-0-5bae9766abfc@kernel.org> In-Reply-To: <20260703-scmi_core_fixes-v3-0-5bae9766abfc@kernel.org> To: arm-scmi@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Cristian Marussi X-Mailer: b4 0.15.2 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 Signed-off-by: Sudeep Holla --- 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 12ebf32aa4da..894c3427bc0b 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -2629,21 +2629,31 @@ 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, @@ -2926,6 +2936,7 @@ 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) @@ -2935,18 +2946,22 @@ 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; } -- 2.43.0