From nobody Thu Oct 2 00:57:52 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3E59D303C87; Thu, 25 Sep 2025 20:36:27 +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=1758832589; cv=none; b=Xiwvojz2NUUAd0bxS2l6K3J9mRtwQ0s8Cqe0D2HTdO2y0931VuDaBlW4jSLd0H4jkKIH+s6U1HJoVX3pkXpAZQJvUFznc0/6182ABdsSCodkYyjlVBl46IViQWaJ9HoBc1aWEjC2dvbLSDc8mNZMANXuLCymGn9NpwqCUuhTZ9M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758832589; c=relaxed/simple; bh=bUuDv9Cj31qwosKQlIYpDeI5XqkB/KdNSJdev/qZzu8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NVvslTmD07xFZC6pvk1R8OaJDVxRYFpuAyLoNSgMapeEXmUqd7wqEAAj9APOHxXUq/C3DOipreEAzuWQGKY3xptIxFtERiT3Agk53zvIA6f1OoNCvNZF8/L6Om30TA6tPG8kIjuhn//p3LT2Lepj0Q36QDShczGSCm5DwGntfvo= 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 A72041692; Thu, 25 Sep 2025 13:36:18 -0700 (PDT) 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 094F33F694; Thu, 25 Sep 2025 13:36:23 -0700 (PDT) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, arm-scmi@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, quic_sibis@quicinc.com, dan.carpenter@linaro.org, d-gole@ti.com, souvik.chakravarty@arm.com, Cristian Marussi Subject: [PATCH 02/10] firmware: arm_scmi: Reduce the scope of protocols mutex Date: Thu, 25 Sep 2025 21:35:46 +0100 Message-ID: <20250925203554.482371-3-cristian.marussi@arm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250925203554.482371-1-cristian.marussi@arm.com> References: <20250925203554.482371-1-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 --- drivers/firmware/arm_scmi/driver.c | 53 +++++++++++++++--------------- 1 file changed, 26 insertions(+), 27 deletions(-) diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi= /driver.c index bd56a877fdfc..71ee25b78624 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 @@ -2179,10 +2180,13 @@ 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); - if (ret !=3D proto->id) - goto clean; + /* Finally register the initialized protocol */ + scoped_guard(mutex, &info->protocols_mtx) { + ret =3D idr_alloc(&info->protocols, pi, proto->id, proto->id + 1, + GFP_KERNEL); + if (ret !=3D proto->id) + goto clean; + } =20 /* * Warn but ignore events registration errors since we do not want @@ -2243,25 +2247,22 @@ 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_protocol_instance *pi =3D ERR_PTR(-EPROBE_DEFER); 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; - - /* 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); + scoped_guard(mutex, &info->protocols_mtx) { + pi =3D idr_find(&info->protocols, protocol_id); + if (pi) { + refcount_inc(&pi->users); + return pi; + } } - mutex_unlock(&info->protocols_mtx); + + /* 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); =20 return pi; } @@ -2294,10 +2295,11 @@ 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; @@ -2316,9 +2318,6 @@ 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 2.51.0