[PATCH 1/3] swiotlb: don't panic when the swiotlb buffer can't be allocated

[Christoph Hellwig <hch@xxxxxx>]

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@xxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Tested-by: Conor Dooley <Conor.Dooley@xxxxxxxxxxxxx>
---
 kernel/dma/swiotlb.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index e2ef0864eb1e5..3e992a308c8a1 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -254,8 +254,10 @@ void __init swiotlb_init_remap(bool addressing_limit, 
unsigned int flags,
                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));
-- 
2.30.2