From nobody Tue Feb 10 07:40:06 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3D16E396B63; Wed, 14 Jan 2026 11:47:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768391251; cv=none; b=FDOlGnbTzSKYAkNtgyq2RyA0W5Ruh/Rb0pGG7yYJ0PcR5OdTM6KCL6B/j0dHbk8CEbF49MNqwsLknawhpiivGQGGGN/MbLr8Oex/f1nBZdgLIpgb/FEWpbTAkfNKjM5FKuqUfRuiS3Jb2yEokXr6ZXSHD9W5gClnOUEmuRuH2Ak= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768391251; c=relaxed/simple; bh=uV9vtkOJEybjNf/MnA9A4HVD1UKZz+XltZIp8k2sA3Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rrfFzMHmeJcIgvbGsbYT8JGsASHG5tUu2OH0RkbCpXuB9GOBrQ5j1XQVC5dOHf19TSiS4gqEi4KTboxKNBB5Nxs+Gexk8PLKfuugExesHwKrrrVYA975oo8qpKNYvxxBON7+ixVXaLmWgceuzTGexmvNJ7C4LI3Xwybsbb3eGZw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 001D11424; Wed, 14 Jan 2026 03:47:22 -0800 (PST) Received: from pluto.fritz.box (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 340A13F59E; Wed, 14 Jan 2026 03:47:25 -0800 (PST) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, arm-scmi@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: sudeep.holla@arm.com, james.quinlan@broadcom.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, etienne.carriere@st.com, peng.fan@oss.nxp.com, michal.simek@amd.com, dan.carpenter@linaro.org, d-gole@ti.com, jonathan.cameron@huawei.com, elif.topuz@arm.com, lukasz.luba@arm.com, philip.radford@arm.com, souvik.chakravarty@arm.com, Cristian Marussi Subject: [PATCH v2 02/17] firmware: arm_scmi: Reduce the scope of protocols mutex Date: Wed, 14 Jan 2026 11:46:06 +0000 Message-ID: <20260114114638.2290765-3-cristian.marussi@arm.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260114114638.2290765-1-cristian.marussi@arm.com> References: <20260114114638.2290765-1-cristian.marussi@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Currently the mutex dedicated to the protection of the list of registered protocols is held during all the protocol initialization phase. Such a wide locking region is not needed and causes problem when trying to initialize notifications from within a protocol initialization routine. Reduce the scope of the protocol mutex. Signed-off-by: Cristian Marussi Reviewed-by: Jonathan Cameron --- v1-->v2 - Fixed improper mixed usage of cleanup and goto constructs --- drivers/firmware/arm_scmi/driver.c | 50 ++++++++++++++---------------- 1 file changed, 24 insertions(+), 26 deletions(-) diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi= /driver.c index 7e5429eff35d..b198c58da1dd 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -17,6 +17,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt =20 #include +#include #include #include #include @@ -2123,7 +2124,6 @@ static int scmi_protocol_version_negotiate(struct scm= i_protocol_handle *ph) * all resources management is handled via a dedicated per-protocol devres * group. * - * Context: Assumes to be called with @protocols_mtx already acquired. * Return: A reference to a freshly allocated and initialized protocol ins= tance * or ERR_PTR on failure. On failure the @proto reference is at first * put using @scmi_protocol_put() before releasing all the devres group. @@ -2162,8 +2162,10 @@ scmi_alloc_init_protocol_instance(struct scmi_info *= info, if (ret) goto clean; =20 - ret =3D idr_alloc(&info->protocols, pi, proto->id, proto->id + 1, - GFP_KERNEL); + /* Finally register the initialized protocol */ + mutex_lock(&info->protocols_mtx); + ret =3D idr_alloc(&info->protocols, pi, proto->id, proto->id + 1, GFP_KER= NEL); + mutex_unlock(&info->protocols_mtx); if (ret !=3D proto->id) goto clean; =20 @@ -2226,27 +2228,25 @@ scmi_alloc_init_protocol_instance(struct scmi_info = *info, static struct scmi_protocol_instance * __must_check scmi_get_protocol_instance(const struct scmi_handle *handle, u8 protocol_i= d) { - struct scmi_protocol_instance *pi; struct scmi_info *info =3D handle_to_scmi_info(handle); + const struct scmi_protocol *proto; =20 - mutex_lock(&info->protocols_mtx); - pi =3D idr_find(&info->protocols, protocol_id); - - if (pi) { - refcount_inc(&pi->users); - } else { - const struct scmi_protocol *proto; + scoped_guard(mutex, &info->protocols_mtx) { + struct scmi_protocol_instance *pi; =20 - /* Fails if protocol not registered on bus */ - proto =3D scmi_protocol_get(protocol_id, &info->version); - if (proto) - pi =3D scmi_alloc_init_protocol_instance(info, proto); - else - pi =3D ERR_PTR(-EPROBE_DEFER); + pi =3D idr_find(&info->protocols, protocol_id); + if (pi) { + refcount_inc(&pi->users); + return pi; + } } - mutex_unlock(&info->protocols_mtx); =20 - return pi; + /* Fails if protocol not registered on bus */ + proto =3D scmi_protocol_get(protocol_id, &info->version); + if (!proto) + return ERR_PTR(-EPROBE_DEFER); + + return scmi_alloc_init_protocol_instance(info, proto); } =20 /** @@ -2277,10 +2277,11 @@ void scmi_protocol_release(const struct scmi_handle= *handle, u8 protocol_id) struct scmi_info *info =3D handle_to_scmi_info(handle); struct scmi_protocol_instance *pi; =20 - mutex_lock(&info->protocols_mtx); - pi =3D idr_find(&info->protocols, protocol_id); - if (WARN_ON(!pi)) - goto out; + scoped_guard(mutex, &info->protocols_mtx) { + pi =3D idr_find(&info->protocols, protocol_id); + if (WARN_ON(!pi)) + return; + } =20 if (refcount_dec_and_test(&pi->users)) { void *gid =3D pi->gid; @@ -2299,9 +2300,6 @@ void scmi_protocol_release(const struct scmi_handle *= handle, u8 protocol_id) dev_dbg(handle->dev, "De-Initialized protocol: 0x%X\n", protocol_id); } - -out: - mutex_unlock(&info->protocols_mtx); } =20 void scmi_setup_protocol_implemented(const struct scmi_protocol_handle *ph, --=20 2.52.0