Re: [PATCH 14/15] swiotlb: remove swiotlb_init_with_tbl and swiotlb_init_late_with_tbl

Boris Ostrovsky
2022-03-14T23:13:14Z

On 3/14/22 3:31 AM, Christoph Hellwig wrote:
> @@ -314,6 +293,7 @@ void __init swiotlb_init(bool addressing_limit, unsigned int flags)
> int swiotlb_init_late(size_t size, gfp_t gfp_mask,
> int (*remap)(void *tlb, unsigned long nslabs))
> {
> + struct io_tlb_mem *mem = &io_tlb_default_mem;
> unsigned long nslabs = ALIGN(size >> IO_TLB_SHIFT, IO_TLB_SEGSIZE);
> unsigned long bytes;
> unsigned char *vstart = NULL;
> @@ -355,33 +335,28 @@ int swiotlb_init_late(size_t size, gfp_t gfp_mask,
> (PAGE_SIZE << order) >> 20);
> nslabs = SLABS_PER_PAGE << order;
> }
> - rc = swiotlb_late_init_with_tbl(vstart, nslabs);
> - if (rc)
> - free_pages((unsigned long)vstart, order);
> -
> - return rc;
> -}
> -
> -int
> -swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> -{
> - struct io_tlb_mem *mem = &io_tlb_default_mem;
> - unsigned long bytes = nslabs << IO_TLB_SHIFT;
>
> - if (swiotlb_force_disable)
> - return 0;
> + if (remap)
> + rc = remap(vstart, nslabs);
> + if (rc) {
> + free_pages((unsigned long)vstart, order);
>
> - /* protect against double initialization */
> - if (WARN_ON_ONCE(mem->nslabs))
> - return -ENOMEM;
> + /* Min is 2MB */
> + if (nslabs <= 1024)
> + return rc;
> + nslabs = max(1024UL, ALIGN(nslabs >> 1, IO_TLB_SEGSIZE));
> + goto retry;
> + }

We now end up with two attempts to remap. I think this second one is what we want since it solves the problem I pointed in previous patch.

-boris