Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Received-SPF: Pass (protection.outlook.com: domain of amd.com designates
 165.204.84.17 as permitted sender) receiver=protection.outlook.com;
 client-ip=165.204.84.17; helo=SATLEXMB03.amd.com; pr=C
From:   Abhijit Gangurde <abhijit.gangurde@amd.com>
To:     <gregkh@linuxfoundation.org>, <masahiroy@kernel.org>,
        <linux-kernel@vger.kernel.org>
CC:     <michal.simek@amd.com>, <git@amd.com>, <nikhil.agarwal@amd.com>,
        <Nipun.Gupta@amd.com>, Abhijit Gangurde <abhijit.gangurde@amd.com>
Subject: [PATCH v2 1/4] cdx: Introduce lock to protect controller ops and controller list
Date:   Mon, 31 Jul 2023 17:38:10 +0530
Message-ID: <20230731120813.123247-2-abhijit.gangurde@amd.com>
In-Reply-To: <20230731120813.123247-1-abhijit.gangurde@amd.com>
References: <20230731120813.123247-1-abhijit.gangurde@amd.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 Jul 2023 12:09:47.0085
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 06d123fe-46d8-4961-bfeb-08db91bf0894
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB03.amd.com]
X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF000042AA.namprd03.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB9430
X-Spam-Status: No, score=0.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FORGED_SPF_HELO,
        RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_NONE,
        T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Add a mutex lock to prevent race between controller ops initiated by
the bus subsystem and the controller registration/unregistration.

Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
---
 drivers/cdx/cdx.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
index d2cad4c670a0..66797c8fe400 100644
--- a/drivers/cdx/cdx.c
+++ b/drivers/cdx/cdx.c
@@ -72,6 +72,8 @@
 
 /* CDX controllers registered with the CDX bus */
 static DEFINE_XARRAY_ALLOC(cdx_controllers);
+/* Lock to protect controller ops and controller list */
+static DEFINE_MUTEX(cdx_controller_lock);
 
 /**
  * cdx_dev_reset - Reset a CDX device
@@ -393,6 +395,8 @@ static ssize_t rescan_store(const struct bus_type *bus,
 	if (!val)
 		return -EINVAL;
 
+	mutex_lock(&cdx_controller_lock);
+
 	/* Unregister all the devices on the bus */
 	cdx_unregister_devices(&cdx_bus_type);
 
@@ -405,6 +409,8 @@ static ssize_t rescan_store(const struct bus_type *bus,
 			dev_err(cdx->dev, "cdx bus scanning failed\n");
 	}
 
+	mutex_unlock(&cdx_controller_lock);
+
 	return count;
 }
 static BUS_ATTR_WO(rescan);
@@ -520,9 +526,12 @@ int cdx_register_controller(struct cdx_controller *cdx)
 {
 	int ret;
 
+	mutex_lock(&cdx_controller_lock);
+
 	ret = xa_alloc(&cdx_controllers, &cdx->id, cdx,
 		       XA_LIMIT(0, MAX_CDX_CONTROLLERS - 1), GFP_KERNEL);
 	if (ret) {
+		mutex_unlock(&cdx_controller_lock);
 		dev_err(cdx->dev,
 			"No free index available. Maximum controllers already registered\n");
 		cdx->id = (u8)MAX_CDX_CONTROLLERS;
@@ -531,6 +540,7 @@ int cdx_register_controller(struct cdx_controller *cdx)
 
 	/* Scan all the devices */
 	cdx->ops->scan(cdx);
+	mutex_unlock(&cdx_controller_lock);
 
 	return 0;
 }
@@ -541,8 +551,12 @@ void cdx_unregister_controller(struct cdx_controller *cdx)
 	if (cdx->id >= MAX_CDX_CONTROLLERS)
 		return;
 
+	mutex_lock(&cdx_controller_lock);
+
 	device_for_each_child(cdx->dev, NULL, cdx_unregister_device);
 	xa_erase(&cdx_controllers, cdx->id);
+
+	mutex_unlock(&cdx_controller_lock);
 }
 EXPORT_SYMBOL_GPL(cdx_unregister_controller);
 
-- 
2.25.1