Re: [PATCH 2/3] swiotlb: use the right nslabs value in swiotlb_init_remap

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 11 May 2022, Christoph Hellwig wrote:
> default_nslabs should only be used to initialize nslabs, after that we
> need to use the local variable that can shrink when allocations or the
> remap don't succeed.
> 
> Fixes: 6424e31b1c05 ("swiotlb: remove swiotlb_init_with_tbl and 
> swiotlb_init_late_with_tbl")
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  kernel/dma/swiotlb.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 3e992a308c8a1..113e1e8aaca37 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -234,7 +234,7 @@ void __init swiotlb_init_remap(bool addressing_limit, 
> unsigned int flags,
>  {
>       struct io_tlb_mem *mem = &io_tlb_default_mem;
>       unsigned long nslabs = default_nslabs;
> -     size_t alloc_size = PAGE_ALIGN(array_size(sizeof(*mem->slots), nslabs));
> +     size_t alloc_size;
>       size_t bytes;
>       void *tlb;
>  
> @@ -249,7 +249,7 @@ void __init swiotlb_init_remap(bool addressing_limit, 
> unsigned int flags,
>        * memory encryption.
>        */
>  retry:
> -     bytes = PAGE_ALIGN(default_nslabs << IO_TLB_SHIFT);
> +     bytes = PAGE_ALIGN(nslabs << IO_TLB_SHIFT);
>       if (flags & SWIOTLB_ANY)
>               tlb = memblock_alloc(bytes, PAGE_SIZE);
>       else
> @@ -269,12 +269,13 @@ void __init swiotlb_init_remap(bool addressing_limit, 
> unsigned int flags,
>               goto retry;
>       }
>  
> +     alloc_size = PAGE_ALIGN(array_size(sizeof(*mem->slots), nslabs));
>       mem->slots = memblock_alloc(alloc_size, PAGE_SIZE);
>       if (!mem->slots)
>               panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
>                     __func__, alloc_size, PAGE_SIZE);
>  
> -     swiotlb_init_io_tlb_mem(mem, __pa(tlb), default_nslabs, false);
> +     swiotlb_init_io_tlb_mem(mem, __pa(tlb), nslabs, false);
>       mem->force_bounce = flags & SWIOTLB_FORCE;
>  
>       if (flags & SWIOTLB_VERBOSE)
> -- 
> 2.30.2
>