swiotlb: clean up some coding style and minor issues

- Fix the used field of struct io_tlb_area wasn't initialized
- Set area number to be 0 if input area number parameter is 0
- Use array_size() to calculate io_tlb_area array size
- Make parameters of swiotlb_do_find_slots() more reasonable

Fixes: 26ffb91fa5e0 ("swiotlb: split up the global swiotlb lock")
Signed-off-by: Tianyu Lan <tiala@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4a6ad177d4b85ff5213bc72242fe938785d943e7..ddca09550f7657185991812235f0d9df1b8996ef 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5907,7 +5907,8 @@
                        Format: { <int> [,<int>] | force | noforce }
                        <int> -- Number of I/O TLB slabs
                        <int> -- Second integer after comma. Number of swiotlb
-                                areas with their own lock. Must be power of 2.
+                                areas with their own lock. Will be rounded up
+                                to a power of 2.
                        force -- force using of bounce buffers even if they
                                 wouldn't be automatically used by the kernel
                        noforce -- Never use bounce buffers (for debugging)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 39dee400443954071793c8ddd9cdf807a2649a24..cc50f1fb127ffc6b578fb9804568db28cd4a51c2 100644 (file)
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -119,7 +119,10 @@ static bool round_up_default_nslabs(void)
 
 static void swiotlb_adjust_nareas(unsigned int nareas)
 {
-       if (!is_power_of_2(nareas))
+       /* use a single area when non is specified */
+       if (!nareas)
+               nareas = 1;
+       else if (!is_power_of_2(nareas))
                nareas = roundup_pow_of_two(nareas);
 
        default_nareas = nareas;
@@ -276,6 +279,7 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
        for (i = 0; i < mem->nareas; i++) {
                spin_lock_init(&mem->areas[i].lock);
                mem->areas[i].index = 0;
+               mem->areas[i].used = 0;
        }
 
        for (i = 0; i < mem->nslabs; i++) {
@@ -358,8 +362,8 @@ retry:
                panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
                      __func__, alloc_size, PAGE_SIZE);
 
-       mem->areas = memblock_alloc(sizeof(struct io_tlb_area) *
-               default_nareas, SMP_CACHE_BYTES);
+       mem->areas = memblock_alloc(array_size(sizeof(struct io_tlb_area),
+               default_nareas), SMP_CACHE_BYTES);
        if (!mem->areas)
                panic("%s: Failed to allocate mem->areas.\n", __func__);
 
@@ -484,7 +488,7 @@ void __init swiotlb_exit(void)
                free_pages((unsigned long)mem->slots, get_order(slots_size));
        } else {
                memblock_free_late(__pa(mem->areas),
-                                  mem->nareas * sizeof(struct io_tlb_area));
+                       array_size(sizeof(*mem->areas), mem->nareas));
                memblock_free_late(mem->start, tbl_size);
                memblock_free_late(__pa(mem->slots), slots_size);
        }
@@ -598,11 +602,12 @@ static unsigned int wrap_area_index(struct io_tlb_mem *mem, unsigned int index)
  * Find a suitable number of IO TLB entries size that will fit this request and
  * allocate a buffer from that IO TLB pool.
  */
-static int swiotlb_do_find_slots(struct io_tlb_mem *mem,
-               struct io_tlb_area *area, int area_index,
-               struct device *dev, phys_addr_t orig_addr,
-               size_t alloc_size, unsigned int alloc_align_mask)
+static int swiotlb_do_find_slots(struct device *dev, int area_index,
+               phys_addr_t orig_addr, size_t alloc_size,
+               unsigned int alloc_align_mask)
 {
+       struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
+       struct io_tlb_area *area = mem->areas + area_index;
        unsigned long boundary_mask = dma_get_seg_boundary(dev);
        dma_addr_t tbl_dma_addr =
                phys_to_dma_unencrypted(dev, mem->start) & boundary_mask;
@@ -691,12 +696,11 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
                size_t alloc_size, unsigned int alloc_align_mask)
 {
        struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
-       int start = raw_smp_processor_id() & ((1U << __fls(mem->nareas)) - 1);
+       int start = raw_smp_processor_id() & (mem->nareas - 1);
        int i = start, index;
 
        do {
-               index = swiotlb_do_find_slots(mem, mem->areas + i, i,
-                                             dev, orig_addr, alloc_size,
+               index = swiotlb_do_find_slots(dev, i, orig_addr, alloc_size,
                                              alloc_align_mask);
                if (index >= 0)
                        return index;