swiotlb: don't panic when the swiotlb buffer can't be allocated

For historical reasons the switlb code paniced when the metadata could
not be allocated, but just printed a warning when the actual main
swiotlb buffer could not be allocated.  Restore this somewhat unexpected
behavior as changing it caused a boot failure on the Microchip RISC-V
PolarFire SoC Icicle kit.

Fixes: 6424e31b1c05 ("swiotlb: remove swiotlb_init_with_tbl and swiotlb_init_late_with_tbl")
Reported-by: Conor Dooley <Conor.Dooley@microchip.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Conor Dooley <Conor.Dooley@microchip.com>

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index e2ef086..3e992a3 100644 (file)
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -254,8 +254,10 @@ retry:
                tlb = memblock_alloc(bytes, PAGE_SIZE);
        else
                tlb = memblock_alloc_low(bytes, PAGE_SIZE);
-       if (!tlb)
-               panic("%s: failed to allocate tlb structure\n", __func__);
+       if (!tlb) {
+               pr_warn("%s: failed to allocate tlb structure\n", __func__);
+               return;
+       }
 
        if (remap && remap(tlb, nslabs) < 0) {
                memblock_free(tlb, PAGE_ALIGN(bytes));