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 8AB9144DB64 for ; Tue, 14 Jul 2026 12:58:47 +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=1784033928; cv=none; b=dx3RVZsKqPxnDXGVgfaObHYb86mELsQ+uX/DKK6/J8UymKVyj9AP/XwcgxhmW7p5d0yTuzpz5A1ekMXTMQLjFV/GNrLynGDgdP8ih6pI51Y4gilcWTEyTYq6+Vfbcpa3u45Fi7kUX/3wom5j/21Ng2i43q8ixn44dbNPonWFNbs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784033928; c=relaxed/simple; bh=Qpa7sHgGYChCnIl9iu5lxCyXUJomMKjB7xZz/HGNXE4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=lyXsJwVOhjNB6K8KTxabg686SI7WdST56xqttRtKtD8FEiEksGIPcRq1T1ZUVMhJI+ctidmsunX5RnAzG+ZlQC0wDA6H7txBEn18paF+b8aqr3C6tLud3tKMTFyNdgdh8EfBGZi6j4yCZGCjJzCDKE58MOjdpNlIhuMFumUxKwA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KF6Hc12N; 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="KF6Hc12N" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E08171F000E9; Tue, 14 Jul 2026 12:58:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784033927; bh=j63KEgZfmI5uVi9AQ1/7Za7dPCkD9AQZOarKSl1v0vE=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=KF6Hc12Nz4bjAX4BEybuBfPo30UK6jOF1IRkHGpmokdwEZh3rOQJSQPSIIxdFgrd+ faOve54ptS9V7pP3uF0XgpLRmOTEnVXewmsttfo+15C8XzCWkg0u59QIUjm8ZxZBqO 83lbV68n27tzfrap+BTlkpZgznT5huoh1AYgsFqoafOQ92s0o2GVWBgr934jeN/+Ak j1fswZKLCKV5bj66hd7w+kqIM2j/k4i8Eq4RtVv6WVmguaGUhnzKuC6qLc0u/lQdPc q9c1FWj8jCxmNYO0aXgOOK4qQLqaC4w08GMiTw+UIEHMm7u8Gx/SG7pOW0qb0nFQZ3 MMov3bClRpyCQ== From: Sudeep Holla Date: Tue, 14 Jul 2026 13:56:29 +0100 Subject: [PATCH v6 10/16] 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: <20260714-scmi_core_fixes-v6-10-3afe499d46e3@kernel.org> References: <20260714-scmi_core_fixes-v6-0-3afe499d46e3@kernel.org> In-Reply-To: <20260714-scmi_core_fixes-v6-0-3afe499d46e3@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 a2871dca24dc..84d1294f269c 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, @@ -2927,6 +2937,7 @@ 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) @@ -2936,18 +2947,22 @@ 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