swiotlb: save io_tlb_used to local variable before leaving critical section (53b29c33) · Commits · 戴 / test

When swiotlb is full, the kernel would print io_tlb_used. However, the result might be inaccurate at that time because we have left the critical section protected by spinlock. Therefore, we backup the io_tlb_used into local variable before leaving critical section. Fixes: ("swiotlb: dump used and total slots when swiotlb buffer is full") Suggested-by:

Håkon Bugge <haakon.bugge@oracle.com> Signed-off-by:

Dongli Zhang <dongli.zhang@oracle.com> Signed-off-by:

Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

kernel/dma/swiotlb.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -445,6 +445,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
		unsigned long mask;
		unsigned long offset_slots;
		unsigned long max_slots;
		unsigned long tmp_io_tlb_used;

		if (no_iotlb_memory)
		panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
		@@ -531,10 +532,12 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
		} while (index != wrap);

		not_found:
		tmp_io_tlb_used = io_tlb_used;

		spin_unlock_irqrestore(&io_tlb_lock, flags);
		if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu, used %lu\n",
		size, io_tlb_nslabs, io_tlb_used);
		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
		size, io_tlb_nslabs, tmp_io_tlb_used);
		return DMA_MAPPING_ERROR;
		found:
		io_tlb_used += nslots;

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