From nobody Sun Dec 14 06:20:50 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 6BB1D269B11; Mon, 28 Apr 2025 09:23:32 +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=1745832213; cv=none; b=Ufle+eFLTeqLEDKkze2EBBqHNT7mX+F40gSHbd7FA7mPm4oquJUQaiHhlCfL5NF7v3Iyca7vlD4bCcZWNNBPV9dNoIlaJ7jHGgTYxVn1bw8eCfXVKH+BIaanp3Jse4zcaeDbPjvUo3dlAArZtWODr4f6h7khwJKD/2XwJdOCBAk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745832213; c=relaxed/simple; bh=zDzlqykv86nTBfYEytc8wm5wkFShzSQKAsrmEhNbBwU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=raiyYjIHc+7gNG19YhNWOr3swRrJhU0/mNkEDe7rnRQ6FFH/4A37C0pmSR5DKUYWcC5gf2OBta1AGmZx8ndyf/nMjwV/6hzAjvj7Jw2/dbv/+EiY0WR3PbWyKACJ4FUs+CXCzirrVddc1AJHGv6IA7wtkwWV2cahgJiSf1C+2Uo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=S1d90qh8; 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="S1d90qh8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31E69C4CEE9; Mon, 28 Apr 2025 09:23:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745832212; bh=zDzlqykv86nTBfYEytc8wm5wkFShzSQKAsrmEhNbBwU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S1d90qh8CUE1R68AnclyKFgyc3M3PH8lRc6WjFsjygRgtWsAEkSuXRwZyPk5H2mWM yCIjmPjwBIzNqNOH29THOBXxLDDuAZw5RIzE+DbuJITHoomDA8eEEMQ24PeQgAyr9A zmhitSbQdvMeIgR+oZ5F+ZZ8YiqyBnwmEK2fSCJajwUgYutk+OX5i7mjlkL88cgAmv AYmthdpUSXspJkugyHwrF2tpdEh2aUssZitwTMgxeS9uC/9y7HeLUu/Ov6P8e9WkBZ RDhA7gkiFAOg5KHkp69Haf5Or2OAtnLQpJilA1Vti+fDK5ZkFfVMcaWVVXQOIyx3E/ fi+Uw3fAUJHUg== From: Leon Romanovsky To: Marek Szyprowski , Jens Axboe , Christoph Hellwig , Keith Busch Cc: 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 v10 08/24] dma-mapping: add a dma_need_unmap helper Date: Mon, 28 Apr 2025 12:22:14 +0300 Message-ID: <448112d7b47869724d99b00de052127fc9d81612.1745831017.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