From nobody Tue Feb 10 02:46:32 2026 Received: from mta20.hihonor.com (mta20.honor.com [81.70.206.69]) (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 9D4D17483; Fri, 16 May 2025 09:32:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=81.70.206.69 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747387943; cv=none; b=erv6UZLppyNvMHa8dL4R2O6dCB1AeKp1HKt+uu94dwQHfgXH7nCjd+iW09R1FgqkItC7rc22YQVR/tJrEfm5/9cOjcbMS2j5qAdy0vm8hdmQiZEzt9Yp6ZiJslYvfSXCjbm/R7cOm+SIqQRpsWQdmx9lSHIrhVD89/HAKdnGrnU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747387943; c=relaxed/simple; bh=WSFU4n/axdeaDEjWRdFN8SACosPXM8iaSf+kxliEvzg=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=m2INCiSqe3ysHJmHswgkd5V4gDtVIi1qvf+TXHhVwRQuhrpVtne8SGCpypyjXTj1iDGeaQl/qwkFBjdXQFJp6NSqAWvcfZmP0QvrfhBOdCfvjv4Na+sW5z915HF5Yodx7WyBanfeM/+uxOEsnfqRSnANsqWHoQsZnmisehcSMXU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=honor.com; spf=pass smtp.mailfrom=honor.com; arc=none smtp.client-ip=81.70.206.69 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=honor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=honor.com Received: from w002.hihonor.com (unknown [10.68.28.120]) by mta20.hihonor.com (SkyGuard) with ESMTPS id 4ZzMGh2Tt6zYlfv7; Fri, 16 May 2025 17:29:16 +0800 (CST) Received: from a010.hihonor.com (10.68.16.52) by w002.hihonor.com (10.68.28.120) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 16 May 2025 17:31:21 +0800 Received: from localhost.localdomain (10.144.18.117) by a010.hihonor.com (10.68.16.52) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 16 May 2025 17:31:20 +0800 From: wangtao To: , , , , , CC: , , , , , , , , wangtao Subject: [PATCH v2 1/2] dmabuf: add DMA_BUF_IOCTL_RW_FILE Date: Fri, 16 May 2025 17:21:47 +0800 Message-ID: <20250516092148.12778-2-tao.wangtao@honor.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20250516092148.12778-1-tao.wangtao@honor.com> References: <20250516092148.12778-1-tao.wangtao@honor.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: w002.hihonor.com (10.68.28.120) To a010.hihonor.com (10.68.16.52) Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add DMA_BUF_IOCTL_RW_FILE to save/restore data to/from a dma-buf. For large dmabuf operations (model loading, real-time data capture, task snapshots), Direct I/O with zero-copy boosts performance by avoiding file cache/memory copies, cuts CPU/power use. On UFS 4.0 (@4GB/s): dmabuf Direct I/O hits 3776MB/s read speed. Signed-off-by: wangtao --- drivers/dma-buf/dma-buf.c | 8 ++++++++ include/linux/dma-buf.h | 15 +++++++++++++++ include/uapi/linux/dma-buf.h | 28 ++++++++++++++++++++++++++++ 3 files changed, 51 insertions(+) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 5baa83b85515..95d8b0158ffd 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -460,6 +460,7 @@ static long dma_buf_ioctl(struct file *file, struct dma_buf *dmabuf; struct dma_buf_sync sync; enum dma_data_direction direction; + struct dma_buf_rw_file kfile; int ret; =20 dmabuf =3D file->private_data; @@ -504,6 +505,13 @@ static long dma_buf_ioctl(struct file *file, return dma_buf_import_sync_file(dmabuf, (const void __user *)arg); #endif =20 + case DMA_BUF_IOCTL_RW_FILE: + if (copy_from_user(&kfile, (void __user *) arg, sizeof(kfile))) + return -EFAULT; + if (!dmabuf->ops->rw_file) + return -EINVAL; + return dmabuf->ops->rw_file(dmabuf, &kfile); + default: return -ENOTTY; } diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 36216d28d8bd..6d2e6eae0611 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -22,6 +22,7 @@ #include #include #include +#include =20 struct device; struct dma_buf; @@ -285,6 +286,20 @@ struct dma_buf_ops { =20 int (*vmap)(struct dma_buf *dmabuf, struct iosys_map *map); void (*vunmap)(struct dma_buf *dmabuf, struct iosys_map *map); + + /** + * @rw_file: + * + * If an Exporter needs to support Direct I/O file operations, it can + * implement this optional callback. The exporter must verify that no + * other objects hold the sg_table, ensure exclusive access to the + * dmabuf's sg_table, and only then proceed with the I/O operation. + * + * Returns: + * + * 0 on success or a negative error code on failure. + */ + int (*rw_file)(struct dma_buf *dmabuf, struct dma_buf_rw_file *file); }; =20 /** diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h index 5a6fda66d9ad..9b33279fef00 100644 --- a/include/uapi/linux/dma-buf.h +++ b/include/uapi/linux/dma-buf.h @@ -167,6 +167,28 @@ struct dma_buf_import_sync_file { __s32 fd; }; =20 +/** + * struct dma_buf_rw_file - read/write file associated with a dma-buf + * + * Userspace can performs a DMA_BUF_IOCTL_BACK to save data from a dma-buf= or + * restore data to a dma-buf. + */ +struct dma_buf_rw_file { + /** @flags: Flags indicating read/write for this dma-buf. */ + __u32 flags; + /** @fd: File descriptor of the file associated with this dma-buf. */ + __s32 fd; + /** @file_offset: Offset within the file where this dma-buf starts. + * + * Offset and Length must be page-aligned for direct I/O. + */ + __u64 file_offset; + /** @buf_offset: Offset within this dma-buf where the read/write starts. = */ + __u64 buf_offset; + /** @buf_len: Length of this dma-buf read/write. */ + __u64 buf_len; +}; + #define DMA_BUF_BASE 'b' #define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync) =20 @@ -179,4 +201,10 @@ struct dma_buf_import_sync_file { #define DMA_BUF_IOCTL_EXPORT_SYNC_FILE _IOWR(DMA_BUF_BASE, 2, struct dma_b= uf_export_sync_file) #define DMA_BUF_IOCTL_IMPORT_SYNC_FILE _IOW(DMA_BUF_BASE, 3, struct dma_bu= f_import_sync_file) =20 +#define DMA_BUF_RW_FLAGS_OP_MASK (0xFF << 0) +#define DMA_BUF_RW_FLAGS_READ (1 << 0) /* Restore dma-buf data */ +#define DMA_BUF_RW_FLAGS_WRITE (2 << 0) /* Save dma-buf data */ +#define DMA_BUF_RW_FLAGS_DIRECT (1u << 31) /* Direct read/write file */ +#define DMA_BUF_IOCTL_RW_FILE _IOW(DMA_BUF_BASE, 4, struct dma_buf_rw_file) + #endif --=20 2.17.1