From 4aa095ea329d76aeb2ae043e0d1ed96049d47940 Mon Sep 17 00:00:00 2001 From: Florian Fainelli Date: Tue, 11 Jun 2019 10:58:25 -0700 Subject: swiotlb: Return consistent SWIOTLB segments/nr_tbl With a specifically contrived memory layout where there is no physical memory available to the kernel below the 4GB boundary, we will fail to perform the initial swiotlb_init() call and set no_iotlb_memory to true. There are drivers out there that call into swiotlb_nr_tbl() to determine whether they can use the SWIOTLB. With the right DMA_BIT_MASK() value for these drivers (say 64-bit), they won't ever need to hit swiotlb_tbl_map_single() so this can go unoticed and we would be possibly lying about those drivers. Signed-off-by: Florian Fainelli Signed-off-by: Konrad Rzeszutek Wilk --- kernel/dma/swiotlb.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 20f414f713e5..72506085795c 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -128,15 +128,17 @@ setup_io_tlb_npages(char *str) } early_param("swiotlb", setup_io_tlb_npages); +static bool no_iotlb_memory; + unsigned long swiotlb_nr_tbl(void) { - return io_tlb_nslabs; + return unlikely(no_iotlb_memory) ? 0 : io_tlb_nslabs; } EXPORT_SYMBOL_GPL(swiotlb_nr_tbl); unsigned int swiotlb_max_segment(void) { - return max_segment; + return unlikely(no_iotlb_memory) ? 0 : max_segment; } EXPORT_SYMBOL_GPL(swiotlb_max_segment); @@ -159,8 +161,6 @@ unsigned long swiotlb_size_or_default(void) return size ? size : (IO_TLB_DEFAULT_SIZE); } -static bool no_iotlb_memory; - void swiotlb_print_info(void) { unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT; -- cgit v1.2.3