From patchwork Sat Aug 3 00:18:14 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Riyan Dhiman X-Patchwork-Id: 13752326 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 64471C3DA4A for ; Sat, 3 Aug 2024 10:33:00 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A147610E02E; Sat, 3 Aug 2024 10:32:59 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="QnFKHeTn"; dkim-atps=neutral Received: from mail-pl1-f181.google.com (mail-pl1-f181.google.com [209.85.214.181]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8090A10E00E for ; Sat, 3 Aug 2024 00:18:23 +0000 (UTC) Received: by mail-pl1-f181.google.com with SMTP id d9443c01a7336-1fc56fd4de1so28310165ad.0 for ; Fri, 02 Aug 2024 17:18:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1722644303; x=1723249103; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=QAWRuSmJKjlpvA4QhYPB4hwoTefNcdDnXSOAB90DYYc=; b=QnFKHeTnN0EBKtHkGVX8nKkSs26sojMnl5I1mL1kWHIgoQdo1KcIn0b3faEUbNb2s4 hjGCXZGoEDxLHkMnJTUKknGYZeUXl06atU9KgLEaVerG/PQyrDLBqx6iYLntWXnITMMw 0TzGeCCfnKY/t4GZ5zN9sFIu0g92mK3RC7BjX6f7cs0XDOra6q0a47y7vmDor4JuYNOp kEXbM5qHrQA3eJvtGcQjSqWEl8DEWgeI36SBlWDVimZHIrbDWTXYNEIBtDVwJHnQy7Xo cd3wGVidCyOrjxoReyOOe/najcTmpUtT5oSxDNwQiKruLNKeeJWLxH9mri9A5pjLQKmQ WJcg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722644303; x=1723249103; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=QAWRuSmJKjlpvA4QhYPB4hwoTefNcdDnXSOAB90DYYc=; b=Kc3Vp1G5be519TJJhlB+dtzC2XquzbGeZbuqiwHjWV0ON+yrEHa8SdR2soQyCE2IdI 9RY/SImrPDVEM0sgBBYts1W+Et0jsjKXEwvdCh721iKWHCky4TXFFGbgq5i3PwoXf9xP SodeKy/nZTmxN1gzxQzM830/s6wDM5BqzQMe3ygGqk7roPFfqUBcv4ve1zUJR+ShzOwQ Ck+wBirmYN9P5BpbX0TPeFP70K9TQ6b/mvLEzp855LCq+Ffcy00ZCceSMF/qlHppGZUi xGu3nf9t/l+gpPINcge0aVo/i8I8gxT/1bAFGt8YFbm6XrK4dsbaT6DMeeO2L0N7SCQr NMlQ== X-Gm-Message-State: AOJu0YyyECgbV/bs0ItnSn+QmS/Yg1BUa+qMl1bfx2OYJ405yuUGsD2B NUNjtbhKH3wp5Pq2gYVlrCMUCxwCAUmjQWFStAqiJivPlyq9yitF X-Google-Smtp-Source: AGHT+IEXMJ/xDGW0/TPd6BplXEHx1lumggDv01n9rtt4EZzLr+h7VIsu0WAr2fg3YtCCKSnHroS3ZA== X-Received: by 2002:a17:903:41c8:b0:1fd:6ca4:f987 with SMTP id d9443c01a7336-1ff57bc504emr73575585ad.15.1722644302627; Fri, 02 Aug 2024 17:18:22 -0700 (PDT) Received: from Riyan.inspiron ([122.176.204.21]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1ff59178248sm23542255ad.202.2024.08.02.17.18.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Aug 2024 17:18:22 -0700 (PDT) From: Riyan Dhiman To: gregkh@linuxfoundation.org Cc: dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, Riyan Dhiman Subject: [PATCH] staging: vme_user: vme_bridge.h: Document mutex in vme_dma_resource structure Date: Sat, 3 Aug 2024 05:48:14 +0530 Message-Id: <20240803001814.7752-1-riyandhiman14@gmail.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-Mailman-Approved-At: Sat, 03 Aug 2024 10:32:58 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Adhere to Linux kernel coding style Reported by checkpatch: CHECK: mutex definition without comment Proof for comment: 1. The mutex is used to protect access to the 'running' list (line 1798 tsi148_dma_list_exec function) mutex_lock(&ctrlrl->mtx); if (!list_empty(&ctrlr->running)) { mutex_unlock(&ctrlr->mtx); return -EBUSY; } This prevents race conditions when multiple threads attempt to start DMA operations simultaneously. 2. It's also used when removing DMA list from running list: (line 1862 tsi148_dma_list_exec function) mutex_lock(&ctrlr->mtx); list_del(&list->list); mutex_unlock(&ctrlr->mtx); Ensuring thread-safe modification of the controller's state. Without this mutex, concurrent access to the DMA controller's state could lead to data corruption or inconsistant state. Signed-off-by: Riyan Dhiman --- drivers/staging/vme_user/vme_bridge.h | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/staging/vme_user/vme_bridge.h b/drivers/staging/vme_user/vme_bridge.h index 9bdc41bb6602..bb3750b40eb1 100644 --- a/drivers/staging/vme_user/vme_bridge.h +++ b/drivers/staging/vme_user/vme_bridge.h @@ -61,6 +61,7 @@ struct vme_dma_list { struct vme_dma_resource { struct list_head list; struct vme_bridge *parent; + /* Mutex to protect DMA controller resources and ensure thread-safe operations */ struct mutex mtx; int locked; int number;