kernel/linux.git/include/linux/scatterlist.h, branch v6.12.80

scatterlist: fix incorrect func name in kernel-doc

2024-12-14T19:03:18+00:00

[ Upstream commit d89c8ec0546184267cb211b579514ebaf8916100 ] Fix a kernel-doc warning by making the kernel-doc function description match the function name: include/linux/scatterlist.h:323: warning: expecting prototype for sg_unmark_bus_address(). Prototype was for sg_dma_unmark_bus_address() instead Link: https://lkml.kernel.org/r/20241130022406.537973-1-rdunlap@infradead.org Fixes: 42399301203e ("lib/scatterlist: add flag for indicating P2PDMA segments in an SGL") Signed-off-by: Randy Dunlap Cc: Logan Gunthorpe Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

swiotlb: reduce swiotlb pool lookups

2024-07-10T05:59:03+00:00

With CONFIG_SWIOTLB_DYNAMIC enabled, each round-trip map/unmap pair in the swiotlb results in 6 calls to swiotlb_find_pool(). In multiple places, the pool is found and used in one function, and then must be found again in the next function that is called because only the tlb_addr is passed as an argument. These are the six call sites: dma_direct_map_page: 1. swiotlb_map -> swiotlb_tbl_map_single -> swiotlb_bounce dma_direct_unmap_page: 2. dma_direct_sync_single_for_cpu -> is_swiotlb_buffer 3. dma_direct_sync_single_for_cpu -> swiotlb_sync_single_for_cpu -> swiotlb_bounce 4. is_swiotlb_buffer 5. swiotlb_tbl_unmap_single -> swiotlb_del_transient 6. swiotlb_tbl_unmap_single -> swiotlb_release_slots Reduce the number of calls by finding the pool at a higher level, and passing it as an argument instead of searching again. A key change is for is_swiotlb_buffer() to return a pool pointer instead of a boolean, and then pass this pool pointer to subsequent swiotlb functions. There are 9 occurrences of is_swiotlb_buffer() used to test if a buffer is a swiotlb buffer before calling a swiotlb function. To reduce code duplication in getting the pool pointer and passing it as an argument, introduce inline wrappers for this pattern. The generated code is essentially unchanged. Since is_swiotlb_buffer() no longer returns a boolean, rename some functions to reflect the change: * swiotlb_find_pool() becomes __swiotlb_find_pool() * is_swiotlb_buffer() becomes swiotlb_find_pool() * is_xen_swiotlb_buffer() becomes xen_swiotlb_find_pool() With these changes, a round-trip map/unmap pair requires only 2 pool lookups (listed using the new names and wrappers): dma_direct_unmap_page: 1. dma_direct_sync_single_for_cpu -> swiotlb_find_pool 2. swiotlb_tbl_unmap_single -> swiotlb_find_pool These changes come from noticing the inefficiencies in a code review, not from performance measurements. With CONFIG_SWIOTLB_DYNAMIC, __swiotlb_find_pool() is not trivial, and it uses an RCU read lock, so avoiding the redundant calls helps performance in a hot path. When CONFIG_SWIOTLB_DYNAMIC is *not* set, the code size reduction is minimal and the perf benefits are likely negligible, but no harm is done. No functional change is intended. Signed-off-by: Michael Kelley Reviewed-by: Petr Tesarik Signed-off-by: Christoph Hellwig

scatterlist: add sg_set_folio()

2023-06-23T23:59:28+00:00

This wrapper for sg_set_page() lets drivers add folios to a scatterlist more easily. We could, perhaps, do better by using a different page in the folio if offset is larger than UINT_MAX, but let's hope we get a better data structure than this before we need to care about such large folios. Link: https://lkml.kernel.org/r/20230621164557.3510324-4-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton

iommu/dma: force bouncing if the size is not cacheline-aligned

2023-06-19T23:19:23+00:00

Similarly to the direct DMA, bounce small allocations as they may have originated from a kmalloc() cache not safe for DMA. Unlike the direct DMA, iommu_dma_map_sg() cannot call iommu_dma_map_sg_swiotlb() for all non-coherent devices as this would break some cases where the iova is expected to be contiguous (dmabuf). Instead, scan the scatterlist for any small sizes and only go the swiotlb path if any element of the list needs bouncing (note that iommu_dma_map_page() would still only bounce those buffers which are not DMA-aligned). To avoid scanning the scatterlist on the 'sync' operations, introduce an SG_DMA_SWIOTLB flag set by iommu_dma_map_sg_swiotlb(). The dev_use_swiotlb() function together with the newly added dev_use_sg_swiotlb() now check for both untrusted devices and unaligned kmalloc() buffers (suggested by Robin Murphy). Link: https://lkml.kernel.org/r/20230612153201.554742-16-catalin.marinas@arm.com Signed-off-by: Catalin Marinas Reviewed-by: Robin Murphy Tested-by: Isaac J. Manjarres Cc: Joerg Roedel Cc: Christoph Hellwig Cc: Alasdair Kergon Cc: Ard Biesheuvel Cc: Arnd Bergmann Cc: Daniel Vetter Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Jerry Snitselaar Cc: Jonathan Cameron Cc: Jonathan Cameron Cc: Lars-Peter Clausen Cc: Logan Gunthorpe Cc: Marc Zyngier Cc: Mark Brown Cc: Mike Snitzer Cc: "Rafael J. Wysocki" Cc: Saravana Kannan Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

dma-mapping: name SG DMA flag helpers consistently

2023-06-19T23:19:22+00:00

sg_is_dma_bus_address() is inconsistent with the naming pattern of its corresponding setters and its own kerneldoc, so take the majority vote and rename it sg_dma_is_bus_address() (and fix up the missing underscores in the kerneldoc too). This gives us a nice clear pattern where SG DMA flags are SG_DMA_, and the helpers for acting on them are sg_dma__(). Link: https://lkml.kernel.org/r/20230612153201.554742-14-catalin.marinas@arm.com Signed-off-by: Robin Murphy Signed-off-by: Catalin Marinas Reviewed-by: Christoph Hellwig Reviewed-by: Jerry Snitselaar Reviewed-by: Logan Gunthorpe Link: https://lore.kernel.org/r/fa2eca2862c7ffc41b50337abffb2dfd2864d3ea.1685036694.git.robin.murphy@arm.com Tested-by: Isaac J. Manjarres Cc: Alasdair Kergon Cc: Ard Biesheuvel Cc: Arnd Bergmann Cc: Daniel Vetter Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Joerg Roedel Cc: Jonathan Cameron Cc: Jonathan Cameron Cc: Lars-Peter Clausen Cc: Marc Zyngier Cc: Mark Brown Cc: Mike Snitzer Cc: "Rafael J. Wysocki" Cc: Saravana Kannan Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

scatterlist: add dedicated config for DMA flags

2023-06-19T23:19:22+00:00

The DMA flags field will be useful for users beyond PCI P2P, so upgrade to its own dedicated config option. [catalin.marinas@arm.com: use #ifdef CONFIG_NEED_SG_DMA_FLAGS in scatterlist.h] [catalin.marinas@arm.com: update PCI_P2PDMA dma_flags comment in scatterlist.h] Link: https://lkml.kernel.org/r/20230612153201.554742-13-catalin.marinas@arm.com Signed-off-by: Robin Murphy Signed-off-by: Catalin Marinas Reviewed-by: Christoph Hellwig Tested-by: Isaac J. Manjarres Cc: Alasdair Kergon Cc: Ard Biesheuvel Cc: Arnd Bergmann Cc: Daniel Vetter Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Jerry Snitselaar Cc: Joerg Roedel Cc: Jonathan Cameron Cc: Jonathan Cameron Cc: Lars-Peter Clausen Cc: Logan Gunthorpe Cc: Marc Zyngier Cc: Mark Brown Cc: Mike Snitzer Cc: "Rafael J. Wysocki" Cc: Saravana Kannan Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

lib/scatterlist: add flag for indicating P2PDMA segments in an SGL

2022-07-26T11:27:47+00:00

Introduce a dma_flags field in struct scatterlist. These flags will be used by dma_[un]map_sg_p2pdma() to determine when a given SGL segments dma_address points to a PCI bus address. dma_unmap_sg_p2pdma() will need to perform different cleanup when a segment is marked as a bus address. The dma_flags field will fit in the existing padding on 64BIT systems (assuming CONFIG_NEED_SG_DMA_LENGTH is also set). The new bit will only be used when CONFIG_PCI_P2PDMA is set; this means PCI P2PDMA will require CONFIG_64BIT. This should be acceptable as the majority of P2PDMA use cases are restricted to newer root complexes and roughly require the extra address space for memory BARs used in the transactions. Signed-off-by: Logan Gunthorpe Signed-off-by: Christoph Hellwig

lib/scatterlist: cleanup macros into static inline functions

2021-12-22T08:21:43+00:00

Convert the sg_is_chain(), sg_is_last() and sg_chain_ptr() macros into static inline functions. There's no reason for these to be macros and static inline are generally preferred these days. Also introduce the SG_PAGE_LINK_MASK define so the P2PDMA work, which is adding another bit to this mask, can do so more easily. Suggested-by: Jason Gunthorpe Signed-off-by: Logan Gunthorpe Reviewed-by: Chaitanya Kulkarni Signed-off-by: Christoph Hellwig

lib/scatterlist: Fix wrong update of orig_nents

2021-08-24T22:52:40+00:00

orig_nents should represent the number of entries with pages, but __sg_alloc_table_from_pages sets orig_nents as the number of total entries in the table. This is wrong when the API is used for dynamic allocation where not all the table entries are mapped with pages. It wasn't observed until now, since RDMA umem who uses this API in the dynamic form doesn't use orig_nents implicit or explicit by the scatterlist APIs. Fix it by changing the append API to track the SG append table state and have an API to free the append table according to the total number of entries in the table. Now all APIs set orig_nents as number of enries with pages. Fixes: 07da1223ec93 ("lib/scatterlist: Add support in dynamic allocation of SG table from pages") Link: https://lore.kernel.org/r/20210824142531.3877007-3-maorg@nvidia.com Signed-off-by: Maor Gottlieb Signed-off-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe

lib/scatterlist: Provide a dedicated function to support table append

2021-08-24T18:21:14+00:00

RDMA is the only in-kernel user that uses __sg_alloc_table_from_pages to append pages dynamically. In the next patch. That mode will be extended and that function will get more parameters. So separate it into a unique function to make such change more clear. Link: https://lore.kernel.org/r/20210824142531.3877007-2-maorg@nvidia.com Signed-off-by: Maor Gottlieb Signed-off-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe