diff options
| author | Jianxin Xiong <jianxin.xiong@intel.com> | 2020-10-14 09:16:01 -0700 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2020-10-15 23:15:43 +0200 |
| commit | ac80cd17a615e472e3dcff0a5446a58540e64e6d (patch) | |
| tree | 44d8ef5a2d724ef5e835c3344717d21a36265a49 | |
| parent | 73b62cdb93b68d7e2c1d373c6a411bc00c53e702 (diff) | |
| download | linux-ac80cd17a615e472e3dcff0a5446a58540e64e6d.tar.bz2 | |
dma-buf: Clarify that dma-buf sg lists are page aligned
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 <jianxin.xiong@intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1602692161-107096-1-git-send-email-jianxin.xiong@intel.com
| -rw-r--r-- | drivers/dma-buf/dma-buf.c | 21 | ||||
| -rw-r--r-- | include/linux/dma-buf.h | 3 |
2 files changed, 23 insertions, 1 deletions
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index a6ba4d598f0e..9db211a2b6cb 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -849,6 +849,9 @@ EXPORT_SYMBOL_GPL(dma_buf_unpin); * 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 @@ -902,6 +905,24 @@ 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 cf77cc15f4ba..03875eaed51a 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -146,7 +146,8 @@ 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 |