From 26405baef41e91f11a7b95b37968344613037236 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 5 May 2025 10:01:45 +0300 Subject: [PATCH] FROMGIT: dma-mapping: add a dma_need_unmap helper 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 Signed-off-by: Marek Szyprowski (cherry picked from commit 5f3b133a23c545272b6bc1e818a5a35e1ca84b1e https://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux.git) Bug: 416098329 Change-Id: I21b5eda3fda17ff4223a5f9a8826cbd26ac3b001 --- 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 eb049aad8e1b..d778e2f6717d 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -410,6 +410,7 @@ static inline bool dma_need_sync(struct device *dev, dma_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) { @@ -435,6 +436,10 @@ static inline bool dma_need_sync(struct device *dev, dma_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 */ struct page *dma_alloc_pages(struct device *dev, size_t size, diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 864a1121bf08..ed1c10e5c242 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -442,6 +442,24 @@ bool __dma_need_sync(struct device *dev, dma_addr_t dma_addr) } EXPORT_SYMBOL_GPL(__dma_need_sync); +/** + * 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_* after + * 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 = get_dma_ops(dev);