From nobody Tue Dec 16 11:08:29 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 AF2951DDA39; Mon, 5 May 2025 07:02:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746428550; cv=none; b=o/uEx2zWxfOy5Vp96sRHQM9JCR/gHavY7hR4+N7HAH4KTVPN0X70LC6IPd9VeB2wqHu4imqNSE0orr9n7zcqr/klWbCx35nXrHFYTotXR3dtxeVDMzR22GSCGYCa2VtDR+djx9z1mKdt63mOoOZy2CMpV9BlQSUlJeKYKXp8OEg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746428550; c=relaxed/simple; bh=zDzlqykv86nTBfYEytc8wm5wkFShzSQKAsrmEhNbBwU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=M0iV4R31euIXK9aX566B9sTWpdlE0ANaZHCDeNAcNTowJS/chWyx9J3osbmtNcKadqtCeTCp5Eiz3mIqiQ8znNMqsvjVWwCtzX/+ea8DtnL8PPXvp6qfWJMHdp6Y2qJiyYtV+5hpJO+9QNiz7pA2MAW6Z6g4rtP+1X142stosjE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qqtM0p4g; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qqtM0p4g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 824E5C4CEE4; Mon, 5 May 2025 07:02:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746428550; bh=zDzlqykv86nTBfYEytc8wm5wkFShzSQKAsrmEhNbBwU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qqtM0p4gWP9l89f4xe03WY9yh8S81jdJOy9cNmMjR+Mi9fNCGSmR3SKl9rQnAZ6HK ifaZF9J3ukpYGHCWk8qbzAYHobwBSK6ZPE9c8zYYX98JeidbQ7xvgllEiqhKw0HOpM dzM7fO8tAGhd7WaF/P3BocqEX/LTe/YP3sRfSN9JLTsTIeDn2vlwVi/rBP3xpLyLA0 Hfk7nonUdMRXWPDCOVNaRXYIZ29to9Zuf/kf5xo6D/n5im+HZTPVbVJ8h8oioMZnvc WaFLtd5J2lafRtA3roO1fRn3KaNxX7b0rzVH9A9CgLTev2i9azW/8Bo4QESW8C3baq DP06qo478a2iw== From: Leon Romanovsky To: Cc: Christoph Hellwig , Jens Axboe , Keith Busch , Jake Edge , Jonathan Corbet , Jason Gunthorpe , Zhu Yanjun , Robin Murphy , Joerg Roedel , Will Deacon , Sagi Grimberg , Bjorn Helgaas , Logan Gunthorpe , Yishai Hadas , Shameer Kolothum , Kevin Tian , Alex Williamson , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Andrew Morton , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-rdma@vger.kernel.org, iommu@lists.linux.dev, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, Niklas Schnelle , Chuck Lever , Luis Chamberlain , Matthew Wilcox , Dan Williams , Kanchan Joshi , Chaitanya Kulkarni , Leon Romanovsky Subject: [PATCH v11 8/9] dma-mapping: add a dma_need_unmap helper Date: Mon, 5 May 2025 10:01:45 +0300 Message-ID: <11ca5400460fa195692bd413387b06ac484e03b4.1746424934.git.leon@kernel.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: References: 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" From: Christoph Hellwig Add helper that allows a driver to skip calling dma_unmap_* if the DMA layer can guarantee that they are no-nops. Signed-off-by: Christoph Hellwig Tested-by: Jens Axboe Reviewed-by: Luis Chamberlain Signed-off-by: Leon Romanovsky --- include/linux/dma-mapping.h | 5 +++++ kernel/dma/mapping.c | 18 ++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index a71e110f1e9d..d2f358c5a25d 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -406,6 +406,7 @@ static inline bool dma_need_sync(struct device *dev, dm= a_addr_t dma_addr) { return dma_dev_need_sync(dev) ? __dma_need_sync(dev, dma_addr) : false; } +bool dma_need_unmap(struct device *dev); #else /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */ static inline bool dma_dev_need_sync(const struct device *dev) { @@ -431,6 +432,10 @@ static inline bool dma_need_sync(struct device *dev, d= ma_addr_t dma_addr) { return false; } +static inline bool dma_need_unmap(struct device *dev) +{ + return false; +} #endif /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */ =20 struct page *dma_alloc_pages(struct device *dev, size_t size, diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index cda127027e48..3c3204ad2839 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -443,6 +443,24 @@ bool __dma_need_sync(struct device *dev, dma_addr_t dm= a_addr) } EXPORT_SYMBOL_GPL(__dma_need_sync); =20 +/** + * dma_need_unmap - does this device need dma_unmap_* operations + * @dev: device to check + * + * If this function returns %false, drivers can skip calling dma_unmap_* a= fter + * finishing an I/O. This function must be called after all mappings that= might + * need to be unmapped have been performed. + */ +bool dma_need_unmap(struct device *dev) +{ + if (!dma_map_direct(dev, get_dma_ops(dev))) + return true; + if (!dev->dma_skip_sync) + return true; + return IS_ENABLED(CONFIG_DMA_API_DEBUG); +} +EXPORT_SYMBOL_GPL(dma_need_unmap); + static void dma_setup_need_sync(struct device *dev) { const struct dma_map_ops *ops =3D get_dma_ops(dev); --=20 2.49.0