diff --git a/rust/helpers/dma.c b/rust/helpers/dma.c index 9fbeb507b08c..ff8f24dae9df 100644 --- a/rust/helpers/dma.c +++ b/rust/helpers/dma.c @@ -49,3 +49,8 @@ __rust_helper void rust_helper_dma_set_max_seg_size(struct device *dev, { dma_set_max_seg_size(dev, size); } + +__rust_helper unsigned int rust_helper_dma_get_max_seg_size(struct device *dev) +{ + return dma_get_max_seg_size(dev); +} diff --git a/rust/kernel/scatterlist.rs b/rust/kernel/scatterlist.rs index b83c468b5c63..44eeafed05e3 100644 --- a/rust/kernel/scatterlist.rs +++ b/rust/kernel/scatterlist.rs @@ -350,15 +350,23 @@ fn new( page_vec.push(page.as_ptr(), flags)?; } + // Cap segments at both the DMA mapping-path limit and the device's declared + // max segment size. + // // `dma_max_mapping_size` returns `size_t`, but `sg_alloc_table_from_pages_segment()` takes // an `unsigned int`. // // SAFETY: `dev.as_raw()` is a valid pointer to a `struct device`. - let max_segment = match unsafe { bindings::dma_max_mapping_size(dev.as_raw()) } { + let max_mapping_size = match unsafe { bindings::dma_max_mapping_size(dev.as_raw()) } { 0 => u32::MAX, - max_segment => u32::try_from(max_segment).unwrap_or(u32::MAX), + max_mapping_size => u32::try_from(max_mapping_size).unwrap_or(u32::MAX), }; + // SAFETY: `dev.as_raw()` is a valid pointer to a `struct device`. + let max_seg_size = unsafe { bindings::dma_get_max_seg_size(dev.as_raw()) }; + + let max_segment = max_mapping_size.min(max_seg_size); + Ok(try_pin_init!(&this in Self { // SAFETY: // - `page_vec` is a `KVec` of valid `struct page *` obtained from `pages`.