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authorFlorian Fainelli <f.fainelli@gmail.com>2019-06-11 10:58:25 -0700
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2019-06-11 14:36:33 -0400
commit4aa095ea329d76aeb2ae043e0d1ed96049d47940 (patch)
treebfd0952a76628ee9ff1e709fc3429147a510e4ad
parent0bfaffbf4cc6f380a83eabc679c0d6eb307cf6e4 (diff)
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 <f.fainelli@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
-rw-r--r--kernel/dma/swiotlb.c8
1 files changed, 4 insertions, 4 deletions
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;