Commit 62bad54b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'dma-mapping-6.3-2023-03-31' of git://git.infradead.org/users/hch/dma-mapping 

Pull dma-mapping fixes from Christoph Hellwig:

 - fix for swiotlb deadlock due to wrong alignment checks (GuoRui.Yu,
   Petr Tesarik)

* tag 'dma-mapping-6.3-2023-03-31' of git://git.infradead.org/users/hch/dma-mapping:
  swiotlb: fix slot alignment checks
  swiotlb: use wrap_area_index() instead of open-coding it
  swiotlb: fix the deadlock in swiotlb_do_find_slots
parents 10f76dc3 0eee5ae1

kernel/dma/swiotlb.c

+16 −13
Original line number Diff line number Diff line
@@ -625,8 +625,8 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, 
	unsigned int iotlb_align_mask =

		dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1);

	unsigned int nslots = nr_slots(alloc_size), stride;

	unsigned int index, wrap, count = 0, i;

	unsigned int offset = swiotlb_align_offset(dev, orig_addr);

	unsigned int index, slots_checked, count = 0, i;

	unsigned long flags;

	unsigned int slot_base;

	unsigned int slot_index;
@@ -634,30 +634,35 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, 
	BUG_ON(!nslots);

	BUG_ON(area_index >= mem->nareas);



	/*

	 * For allocations of PAGE_SIZE or larger only look for page aligned

	 * allocations.

	 */

	if (alloc_size >= PAGE_SIZE)

		iotlb_align_mask &= PAGE_MASK;

	iotlb_align_mask &= alloc_align_mask;



	/*

	 * For mappings with an alignment requirement don't bother looping to

	 * unaligned slots once we found an aligned one.  For allocations of

	 * PAGE_SIZE or larger only look for page aligned allocations.

	 * unaligned slots once we found an aligned one.

	 */

	stride = (iotlb_align_mask >> IO_TLB_SHIFT) + 1;

	if (alloc_size >= PAGE_SIZE)

		stride = max(stride, stride << (PAGE_SHIFT - IO_TLB_SHIFT));

	stride = max(stride, (alloc_align_mask >> IO_TLB_SHIFT) + 1);



	spin_lock_irqsave(&area->lock, flags);

	if (unlikely(nslots > mem->area_nslabs - area->used))

		goto not_found;



	slot_base = area_index * mem->area_nslabs;

	index = wrap = wrap_area_index(mem, ALIGN(area->index, stride));

	index = area->index;



	do {

	for (slots_checked = 0; slots_checked < mem->area_nslabs; ) {

		slot_index = slot_base + index;



		if (orig_addr &&

		    (slot_addr(tbl_dma_addr, slot_index) &

		     iotlb_align_mask) != (orig_addr & iotlb_align_mask)) {

			index = wrap_area_index(mem, index + 1);

			slots_checked++;

			continue;

		}
@@ -673,7 +678,8 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, 
				goto found;

		}

		index = wrap_area_index(mem, index + stride);

	} while (index != wrap);

		slots_checked += stride;

	}



not_found:

	spin_unlock_irqrestore(&area->lock, flags);
@@ -693,10 +699,7 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, 
	/*

	 * Update the indices to avoid searching in the next round.

	 */

	if (index + nslots < mem->area_nslabs)

		area->index = index + nslots;

	else

		area->index = 0;

	area->index = wrap_area_index(mem, index + nslots);

	area->used += nslots;

	spin_unlock_irqrestore(&area->lock, flags);

	return slot_index;