On Mon, 2018-07-30 at 18:38 +0200, Christoph Hellwig wrote:
> The requirement to disable local irqs over kmap_atomic is long gone,
> so remove those calls.
Really ? I'm trying to verify that and getting lost in a mess of macros
from hell in the per-cpu stuff but if you look at our implementation
of kmap_atomic_prot(), all it does is a preempt_disable(), and then
it uses kmap_atomic_idx_push():
int idx = __this_cpu_inc_return(__kmap_atomic_idx) - 1;
Note the use of __this_cpu_inc_return(), not this_cpu_inc_return(),
ie this is the non-interrupt safe version...
Ben.
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> arch/powerpc/mm/dma-noncoherent.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/mm/dma-noncoherent.c b/arch/powerpc/mm/dma-noncoherent.c
> index 382528475433..d1c16456abac 100644
> --- a/arch/powerpc/mm/dma-noncoherent.c
> +++ b/arch/powerpc/mm/dma-noncoherent.c
> @@ -357,12 +357,10 @@ static inline void __dma_sync_page_highmem(struct page *page,
> {
> size_t seg_size = min((size_t)(PAGE_SIZE - offset), size);
> size_t cur_size = seg_size;
> - unsigned long flags, start, seg_offset = offset;
> + unsigned long start, seg_offset = offset;
> int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE;
> int seg_nr = 0;
>
> - local_irq_save(flags);
> -
> do {
> start = (unsigned long)kmap_atomic(page + seg_nr) + seg_offset;
>
> @@ -378,8 +376,6 @@ static inline void __dma_sync_page_highmem(struct page *page,
> cur_size += seg_size;
> seg_offset = 0;
> } while (seg_nr < nr_segs);
> -
> - local_irq_restore(flags);
> }
> #endif /* CONFIG_HIGHMEM */
>
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