From patchwork Wed Oct 14 16:16:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Xiong, Jianxin" X-Patchwork-Id: 11838021 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5ED3F14B5 for ; Wed, 14 Oct 2020 16:01:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47A80214D8 for ; Wed, 14 Oct 2020 16:01:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729395AbgJNQB6 (ORCPT ); Wed, 14 Oct 2020 12:01:58 -0400 Received: from mga12.intel.com ([192.55.52.136]:46802 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727034AbgJNQB6 (ORCPT ); Wed, 14 Oct 2020 12:01:58 -0400 IronPort-SDR: e1JXhhVj4/hQOKGI0RdC5TmvF9PVx+P9fM50a3+AjtNcjzcr5Bit72U8tuo7IyKnX8pH4/nYWm n3qfTTroMpgA== X-IronPort-AV: E=McAfee;i="6000,8403,9773"; a="145443294" X-IronPort-AV: E=Sophos;i="5.77,375,1596524400"; d="scan'208";a="145443294" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Oct 2020 09:01:57 -0700 IronPort-SDR: DfBAFi75yC9OryKz1lKBNdATthFLHS9uxKfYZOyLJVz0Fi8UM8WCwYyLuCMwP7KMdqzn4AhFHj NVNW30PqycEA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,375,1596524400"; d="scan'208";a="345711986" Received: from cst-dev.jf.intel.com ([10.23.221.69]) by fmsmga004.fm.intel.com with ESMTP; 14 Oct 2020 09:01:57 -0700 From: Jianxin Xiong To: linux-rdma@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org Cc: Jianxin Xiong , Doug Ledford , Jason Gunthorpe , Leon Romanovsky , Sumit Semwal , Christian Koenig , Daniel Vetter Subject: [PATCH v4 5/5] dma-buf: Clarify that dma-buf sg lists are page aligned Date: Wed, 14 Oct 2020 09:16:01 -0700 Message-Id: <1602692161-107096-1-git-send-email-jianxin.xiong@intel.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org The dma-buf API have been used under the assumption that the sg lists returned from dma_buf_map_attachment() are fully page aligned. Lots of stuff can break otherwise all over the place. Clarify this in the documentation and add a check when DMA API debug is enabled. Signed-off-by: Jianxin Xiong Reviewed-by: Christian König --- drivers/dma-buf/dma-buf.c | 21 +++++++++++++++++++++ include/linux/dma-buf.h | 3 ++- 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 844967f..7309c83 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -851,6 +851,9 @@ void dma_buf_unpin(struct dma_buf_attachment *attach) * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR * on error. May return -EINTR if it is interrupted by a signal. * + * On success, the DMA addresses and lengths in the returned scatterlist are + * PAGE_SIZE aligned. + * * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that * the underlying backing storage is pinned for as long as a mapping exists, * therefore users/importers should not hold onto a mapping for undue amounts of @@ -904,6 +907,24 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, attach->dir = direction; } +#ifdef CONFIG_DMA_API_DEBUG + { + struct scatterlist *sg; + u64 addr; + int len; + int i; + + for_each_sgtable_dma_sg(sg_table, sg, i) { + addr = sg_dma_address(sg); + len = sg_dma_len(sg); + if (!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(len)) { + pr_debug("%s: addr %llx or len %x is not page aligned!\n", + __func__, addr, len); + } + } + } +#endif /* CONFIG_DMA_API_DEBUG */ + return sg_table; } EXPORT_SYMBOL_GPL(dma_buf_map_attachment); diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index a2ca294e..4a5fa70 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -145,7 +145,8 @@ struct dma_buf_ops { * * A &sg_table scatter list of or the backing storage of the DMA buffer, * already mapped into the device address space of the &device attached - * with the provided &dma_buf_attachment. + * with the provided &dma_buf_attachment. The addresses and lengths in + * the scatter list are PAGE_SIZE aligned. * * On failure, returns a negative error value wrapped into a pointer. * May also return -EINTR when a signal was received while being