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authorChao Gao <chao.gao@intel.com>2022-07-15 18:45:35 +0800
committerChristoph Hellwig <hch@lst.de>2022-07-18 06:50:01 +0200
commit57e6840cf79a4af84f44af3f8cfeacd8a14a6c6f (patch)
tree066c3e6401fa68816347a4c109db5b94d729af56 /kernel/dma
parent44335487bab05e06902f9184179857aae764bfe6 (diff)
swiotlb: ensure a segment doesn't cross the area boundary
Free slots tracking assumes that slots in a segment can be allocated to fulfill a request. This implies that slots in a segment should belong to the same area. Although the possibility of a violation is low, it is better to explicitly enforce segments won't span multiple areas by adjusting the number of slabs when configuring areas. Signed-off-by: Chao Gao <chao.gao@intel.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'kernel/dma')
-rw-r--r--kernel/dma/swiotlb.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 604f2469ac0e..608923e8dab1 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -91,12 +91,21 @@ struct io_tlb_area {
/*
* Round up number of slabs to the next power of 2. The last area is going
* be smaller than the rest if default_nslabs is not power of two.
+ * The number of slot in an area should be a multiple of IO_TLB_SEGSIZE,
+ * otherwise a segment may span two or more areas. It conflicts with free
+ * contiguous slots tracking: free slots are treated contiguous no matter
+ * whether they cross an area boundary.
*
* Return true if default_nslabs is rounded up.
*/
static bool round_up_default_nslabs(void)
{
- if (!default_nareas || is_power_of_2(default_nslabs))
+ if (!default_nareas)
+ return false;
+
+ if (default_nslabs < IO_TLB_SEGSIZE * default_nareas)
+ default_nslabs = IO_TLB_SEGSIZE * default_nareas;
+ else if (is_power_of_2(default_nslabs))
return false;
default_nslabs = roundup_pow_of_two(default_nslabs);
return true;