Messages in this thread | | | Date | Tue, 4 Dec 2018 15:22:16 +0100 | From | Christoph Hellwig <> | Subject | Re: [PATCH 4/9] dma-mapping: move the arm64 ncoherent alloc/free support to common code |
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> > +int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot) > > +{ > > + unsigned int pool_size_order = get_order(atomic_pool_size); > > + unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT; > > + struct page *page; > > + void *addr; > > + int ret; > > + > > + if (dev_get_cma_area(NULL)) > > + page = dma_alloc_from_contiguous(NULL, nr_pages, > > + pool_size_order, false); > > + else > > + page = alloc_pages(gfp, pool_size_order); > > + if (!page) > > + goto out; > > + > > + memset(page_address(page), 0, atomic_pool_size); > > Note that this won't work if 'page' is a highmem page - should there > be a check for that, or a check for the gfp flags? > > Also, is this memset() actually useful, or a waste of cycles - when we > allocate from this pool (see dma_alloc_from_pool()), we always memset() > the buffer.
Currently there is no user that supports highmem, but yes, the memset should probably simply be removed.
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