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[PATCH 13/14] swiotlb: dynamically allocate io_tlb_default_mem



Instead of allocating ->list and ->orig_addr separately just do one
dynamic allocation for the actual io_tlb_mem structure.  This simplifies
a lot of the initialization code, and also allows to just check
io_tlb_default_mem to see if swiotlb is in use.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 drivers/xen/swiotlb-xen.c |  22 +--
 include/linux/swiotlb.h   |  18 ++-
 kernel/dma/swiotlb.c      | 300 +++++++++++++-------------------------
 3 files changed, 117 insertions(+), 223 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 5329ad54a5f34e..4c89afc0df6289 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -158,17 +158,14 @@ static const char *xen_swiotlb_error(enum xen_swiotlb_err 
err)
 int __ref xen_swiotlb_init(void)
 {
        enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN;
-       unsigned long nslabs, bytes, order;
-       unsigned int repeat = 3;
+       unsigned long bytes = swiotlb_size_or_default();
+       unsigned long nslabs = bytes >> IO_TLB_SHIFT;
+       unsigned int order, repeat = 3;
        int rc = -ENOMEM;
        char *start;
 
-       nslabs = swiotlb_nr_tbl();
-       if (!nslabs)
-               nslabs = DEFAULT_NSLABS;
 retry:
        m_ret = XEN_SWIOTLB_ENOMEM;
-       bytes = nslabs << IO_TLB_SHIFT;
        order = get_order(bytes);
 
        /*
@@ -221,19 +218,16 @@ int __ref xen_swiotlb_init(void)
 #ifdef CONFIG_X86
 void __init xen_swiotlb_init_early(void)
 {
-       unsigned long nslabs, bytes;
+       unsigned long bytes = swiotlb_size_or_default();
+       unsigned long nslabs = bytes >> IO_TLB_SHIFT;
        unsigned int repeat = 3;
        char *start;
        int rc;
 
-       nslabs = swiotlb_nr_tbl();
-       if (!nslabs)
-               nslabs = DEFAULT_NSLABS;
 retry:
        /*
         * Get IO TLB memory from any location.
         */
-       bytes = nslabs << IO_TLB_SHIFT;
        start = memblock_alloc(PAGE_ALIGN(bytes), PAGE_SIZE);
        if (!start)
                panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
@@ -248,8 +242,8 @@ void __init xen_swiotlb_init_early(void)
                if (repeat--) {
                        /* Min is 2MB */
                        nslabs = max(1024UL, (nslabs >> 1));
-                       pr_info("Lowering to %luMB\n",
-                               (nslabs << IO_TLB_SHIFT) >> 20);
+                       bytes = nslabs << IO_TLB_SHIFT;
+                       pr_info("Lowering to %luMB\n", bytes >> 20);
                        goto retry;
                }
                panic("%s (rc:%d)", xen_swiotlb_error(XEN_SWIOTLB_EFIXUP), rc);
@@ -548,7 +542,7 @@ xen_swiotlb_sync_sg_for_device(struct device *dev, struct 
scatterlist *sgl,
 static int
 xen_swiotlb_dma_supported(struct device *hwdev, u64 mask)
 {
-       return xen_phys_to_dma(hwdev, io_tlb_default_mem.end - 1) <= mask;
+       return xen_phys_to_dma(hwdev, io_tlb_default_mem->end - 1) <= mask;
 }
 
 const struct dma_map_ops xen_swiotlb_dma_ops = {
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 5ec5378b17c333..63f7a63f61d098 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -90,28 +90,30 @@ struct io_tlb_mem {
        phys_addr_t end;
        unsigned long nslabs;
        unsigned long used;
-       unsigned int *list;
        unsigned int index;
-       phys_addr_t *orig_addr;
-       size_t *alloc_size;
        spinlock_t lock;
        struct dentry *debugfs;
        bool late_alloc;
+       struct io_tlb_slot {
+               phys_addr_t orig_addr;
+               size_t alloc_size;
+               unsigned int list;
+       } slots[];
 };
-extern struct io_tlb_mem io_tlb_default_mem;
+extern struct io_tlb_mem *io_tlb_default_mem;
 
 static inline bool is_swiotlb_buffer(phys_addr_t paddr)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
+       struct io_tlb_mem *mem = io_tlb_default_mem;
 
-       return paddr >= mem->start && paddr < mem->end;
+       return mem && paddr >= mem->start && paddr < mem->end;
 }
 
 void __init swiotlb_exit(void);
 unsigned int swiotlb_max_segment(void);
 size_t swiotlb_max_mapping_size(struct device *dev);
 bool is_swiotlb_active(void);
-void __init swiotlb_adjust_size(unsigned long new_size);
+void __init swiotlb_adjust_size(unsigned long size);
 #else
 #define swiotlb_force SWIOTLB_NO_FORCE
 static inline bool is_swiotlb_buffer(phys_addr_t paddr)
@@ -135,7 +137,7 @@ static inline bool is_swiotlb_active(void)
        return false;
 }
 
-static inline void swiotlb_adjust_size(unsigned long new_size)
+static inline void swiotlb_adjust_size(unsigned long size)
 {
 }
 #endif /* CONFIG_SWIOTLB */
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 6aa84fa3b1467e..b7bcd7b804bfe8 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -63,7 +63,7 @@
 
 enum swiotlb_force swiotlb_force;
 
-struct io_tlb_mem io_tlb_default_mem;
+struct io_tlb_mem *io_tlb_default_mem;
 
 /*
  * Max segment that we can provide which (if pages are contingous) will
@@ -71,15 +71,15 @@ struct io_tlb_mem io_tlb_default_mem;
  */
 static unsigned int max_segment;
 
+static unsigned long default_nslabs = IO_TLB_DEFAULT_SIZE >> IO_TLB_SHIFT;
+
 static int __init
 setup_io_tlb_npages(char *str)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-
        if (isdigit(*str)) {
-               mem->nslabs = simple_strtoul(str, &str, 0);
                /* avoid tail segment of size < IO_TLB_SEGSIZE */
-               mem->nslabs = ALIGN(mem->nslabs, IO_TLB_SEGSIZE);
+               default_nslabs =
+                       ALIGN(simple_strtoul(str, &str, 0), IO_TLB_SEGSIZE);
        }
        if (*str == ',')
                ++str;
@@ -87,24 +87,22 @@ setup_io_tlb_npages(char *str)
                swiotlb_force = SWIOTLB_FORCE;
        } else if (!strcmp(str, "noforce")) {
                swiotlb_force = SWIOTLB_NO_FORCE;
-               mem->nslabs = 1;
+               default_nslabs = 1;
        }
 
        return 0;
 }
 early_param("swiotlb", setup_io_tlb_npages);
 
-static bool no_iotlb_memory;
-
 unsigned long swiotlb_nr_tbl(void)
 {
-       return unlikely(no_iotlb_memory) ? 0 : io_tlb_default_mem.nslabs;
+       return io_tlb_default_mem ? io_tlb_default_mem->nslabs : 0;
 }
 EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
 
 unsigned int swiotlb_max_segment(void)
 {
-       return unlikely(no_iotlb_memory) ? 0 : max_segment;
+       return io_tlb_default_mem ? max_segment : 0;
 }
 EXPORT_SYMBOL_GPL(swiotlb_max_segment);
 
@@ -118,44 +116,32 @@ void swiotlb_set_max_segment(unsigned int val)
 
 unsigned long swiotlb_size_or_default(void)
 {
-       unsigned long size;
-
-       size = io_tlb_default_mem.nslabs << IO_TLB_SHIFT;
-
-       return size ? size : (IO_TLB_DEFAULT_SIZE);
+       return default_nslabs << IO_TLB_SHIFT;
 }
 
-void __init swiotlb_adjust_size(unsigned long new_size)
+void __init swiotlb_adjust_size(unsigned long size)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-       unsigned long size;
-
        /*
         * If swiotlb parameter has not been specified, give a chance to
         * architectures such as those supporting memory encryption to
         * adjust/expand SWIOTLB size for their use.
         */
-       if (!mem->nslabs) {
-               size = ALIGN(new_size, IO_TLB_SIZE);
-               mem->nslabs = size >> IO_TLB_SHIFT;
-               mem->nslabs = ALIGN(mem->nslabs, IO_TLB_SEGSIZE);
-
-               pr_info("SWIOTLB bounce buffer size adjusted to %luMB", size >> 
20);
-       }
+       size = ALIGN(size, IO_TLB_SIZE);
+       default_nslabs = ALIGN(size >> IO_TLB_SHIFT, IO_TLB_SEGSIZE);
+       pr_info("SWIOTLB bounce buffer size adjusted to %luMB", size >> 20);
 }
 
 void swiotlb_print_info(void)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-       unsigned long bytes = mem->nslabs << IO_TLB_SHIFT;
+       struct io_tlb_mem *mem = io_tlb_default_mem;
 
-       if (no_iotlb_memory) {
+       if (!mem) {
                pr_warn("No low mem\n");
                return;
        }
 
        pr_info("mapped [mem %pa-%pa] (%luMB)\n", &mem->start, &mem->end,
-              bytes >> 20);
+              (mem->nslabs << IO_TLB_SHIFT) >> 20);
 }
 
 static inline unsigned long io_tlb_offset(unsigned long val)
@@ -176,13 +162,12 @@ static inline unsigned long nr_slots(u64 val)
  */
 void __init swiotlb_update_mem_attributes(void)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
+       struct io_tlb_mem *mem = io_tlb_default_mem;
        void *vaddr;
        unsigned long bytes;
 
-       if (no_iotlb_memory || mem->late_alloc)
+       if (!mem || mem->late_alloc)
                return;
-
        vaddr = phys_to_virt(mem->start);
        bytes = PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT);
        set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
@@ -191,49 +176,33 @@ void __init swiotlb_update_mem_attributes(void)
 
 int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-       unsigned long i, bytes;
+       unsigned long bytes = nslabs << IO_TLB_SHIFT, i;
+       struct io_tlb_mem *mem;
        size_t alloc_size;
 
        /* protect against double initialization */
-       if (WARN_ON_ONCE(mem->start))
+       if (WARN_ON_ONCE(io_tlb_default_mem))
                return -ENOMEM;
 
-       bytes = nslabs << IO_TLB_SHIFT;
-
+       alloc_size = PAGE_ALIGN(struct_size(mem, slots, nslabs));
+       mem = memblock_alloc(alloc_size, PAGE_SIZE);
+       if (!mem)
+               panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
+                     __func__, alloc_size, PAGE_SIZE);
        mem->nslabs = nslabs;
        mem->start = __pa(tlb);
        mem->end = mem->start + bytes;
        mem->index = 0;
        spin_lock_init(&mem->lock);
-
-       /*
-        * Allocate and initialize the free list array.  This array is used
-        * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
-        * between mem->start and mem->end.
-        */
-       alloc_size = PAGE_ALIGN(mem->nslabs * sizeof(int));
-       mem->list = memblock_alloc(alloc_size, PAGE_SIZE);
-       if (!mem->list)
-               panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
-                     __func__, alloc_size, PAGE_SIZE);
-
-       alloc_size = PAGE_ALIGN(mem->nslabs * sizeof(phys_addr_t));
-       mem->orig_addr = memblock_alloc(alloc_size, PAGE_SIZE);
-       if (!mem->orig_addr)
-               panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
-                     __func__, alloc_size, PAGE_SIZE);
-
        for (i = 0; i < mem->nslabs; i++) {
-               mem->list[i] = IO_TLB_SEGSIZE - io_tlb_offset(i);
-               mem->orig_addr[i] = INVALID_PHYS_ADDR;
-               mem->alloc_size[i] = 0;
+               mem->slots[i].list = IO_TLB_SEGSIZE - io_tlb_offset(i);
+               mem->slots[i].orig_addr = INVALID_PHYS_ADDR;
+               mem->slots[i].alloc_size = 0;
        }
-       no_iotlb_memory = false;
 
+       io_tlb_default_mem = mem;
        if (verbose)
                swiotlb_print_info();
-
        swiotlb_set_max_segment(mem->nslabs << IO_TLB_SHIFT);
        return 0;
 }
@@ -245,30 +214,21 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long 
nslabs, int verbose)
 void  __init
 swiotlb_init(int verbose)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-       size_t default_size = IO_TLB_DEFAULT_SIZE;
-       unsigned char *vstart;
-       unsigned long bytes;
-
-       if (!mem->nslabs) {
-               mem->nslabs = (default_size >> IO_TLB_SHIFT);
-               mem->nslabs = ALIGN(mem->nslabs, IO_TLB_SEGSIZE);
-       }
-
-       bytes = mem->nslabs << IO_TLB_SHIFT;
+       size_t bytes = PAGE_ALIGN(default_nslabs << IO_TLB_SHIFT);
+       void *tlb;
 
        /* Get IO TLB memory from the low pages */
-       vstart = memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE);
-       if (vstart && !swiotlb_init_with_tbl(vstart, mem->nslabs, verbose))
-               return;
-
-       if (mem->start) {
-               memblock_free_early(mem->start,
-                                   PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT));
-               mem->start = 0;
-       }
+       tlb = memblock_alloc_low(bytes, PAGE_SIZE);
+       if (!tlb)
+               goto fail;
+       if (swiotlb_init_with_tbl(tlb, default_nslabs, verbose))
+               goto fail_free_mem;
+       return;
+
+fail_free_mem:
+       memblock_free_early(__pa(tlb), bytes);
+fail:
        pr_warn("Cannot allocate buffer");
-       no_iotlb_memory = true;
 }
 
 /*
@@ -279,23 +239,19 @@ swiotlb_init(int verbose)
 int
 swiotlb_late_init_with_default_size(size_t default_size)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-       unsigned long bytes, req_nslabs = mem->nslabs;
+       unsigned long nslabs =
+               ALIGN(default_size >> IO_TLB_SHIFT, IO_TLB_SEGSIZE);
+       unsigned long bytes;
        unsigned char *vstart = NULL;
        unsigned int order;
        int rc = 0;
 
-       if (!mem->nslabs) {
-               mem->nslabs = (default_size >> IO_TLB_SHIFT);
-               mem->nslabs = ALIGN(mem->nslabs, IO_TLB_SEGSIZE);
-       }
-
        /*
         * Get IO TLB memory from the low pages
         */
-       order = get_order(mem->nslabs << IO_TLB_SHIFT);
-       mem->nslabs = SLABS_PER_PAGE << order;
-       bytes = mem->nslabs << IO_TLB_SHIFT;
+       order = get_order(nslabs << IO_TLB_SHIFT);
+       nslabs = SLABS_PER_PAGE << order;
+       bytes = nslabs << IO_TLB_SHIFT;
 
        while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
                vstart = (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
@@ -305,43 +261,35 @@ swiotlb_late_init_with_default_size(size_t default_size)
                order--;
        }
 
-       if (!vstart) {
-               mem->nslabs = req_nslabs;
+       if (!vstart)
                return -ENOMEM;
-       }
+
        if (order != get_order(bytes)) {
                pr_warn("only able to allocate %ld MB\n",
                        (PAGE_SIZE << order) >> 20);
-               mem->nslabs = SLABS_PER_PAGE << order;
+               nslabs = SLABS_PER_PAGE << order;
        }
-       rc = swiotlb_late_init_with_tbl(vstart, mem->nslabs);
+       rc = swiotlb_late_init_with_tbl(vstart, nslabs);
        if (rc)
                free_pages((unsigned long)vstart, order);
 
        return rc;
 }
 
-static void swiotlb_cleanup(void)
-{
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-
-       mem->end = 0;
-       mem->start = 0;
-       mem->nslabs = 0;
-       max_segment = 0;
-}
-
 int
 swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
-       unsigned long i, bytes;
+       unsigned long bytes = nslabs << IO_TLB_SHIFT, i;
+       struct io_tlb_mem *mem;
 
        /* protect against double initialization */
-       if (WARN_ON_ONCE(mem->start))
+       if (WARN_ON_ONCE(io_tlb_default_mem))
                return -ENOMEM;
 
-       bytes = nslabs << IO_TLB_SHIFT;
+       mem = (void *)__get_free_pages(GFP_KERNEL,
+               get_order(struct_size(mem, slots, nslabs)));
+       if (!mem)
+               return -ENOMEM;
 
        mem->nslabs = nslabs;
        mem->start = virt_to_phys(tlb);
@@ -349,84 +297,35 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long 
nslabs)
        mem->index = 0;
        mem->late_alloc = 1;
        spin_lock_init(&mem->lock);
+       for (i = 0; i < mem->nslabs; i++) {
+               mem->slots[i].list = IO_TLB_SEGSIZE - io_tlb_offset(i);
+               mem->slots[i].orig_addr = INVALID_PHYS_ADDR;
+               mem->slots[i].alloc_size = 0;
+       }
 
        set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT);
        memset(tlb, 0, bytes);
 
-       /*
-        * Allocate and initialize the free list array.  This array is used
-        * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
-        * between mem->start and mem->end.
-        */
-       mem->list = (unsigned int *)__get_free_pages(GFP_KERNEL,
-                                     get_order(mem->nslabs * sizeof(int)));
-       if (!mem->list)
-               goto cleanup3;
-
-       mem->orig_addr = (phys_addr_t *)
-               __get_free_pages(GFP_KERNEL,
-                                get_order(mem->nslabs *
-                                          sizeof(phys_addr_t)));
-       if (!mem->orig_addr)
-               goto cleanup4;
-
-       mem->alloc_size = (size_t *)
-               __get_free_pages(GFP_KERNEL,
-                                get_order(mem->nslabs *
-                                          sizeof(size_t)));
-       if (!mem->alloc_size)
-               goto cleanup5;
-
-       for (i = 0; i < mem->nslabs; i++) {
-               mem->list[i] = IO_TLB_SEGSIZE - io_tlb_offset(i);
-               mem->orig_addr[i] = INVALID_PHYS_ADDR;
-               mem->alloc_size[i] = 0;
-       }
-       no_iotlb_memory = false;
-
+       io_tlb_default_mem = mem;
        swiotlb_print_info();
        swiotlb_set_max_segment(mem->nslabs << IO_TLB_SHIFT);
        return 0;
-
-cleanup5:
-       free_pages((unsigned long)mem->orig_addr,
-                  get_order(mem->nslabs * sizeof(phys_addr_t)));
-cleanup4:
-       free_pages((unsigned long)mem->list,
-                  get_order(mem->nslabs * sizeof(int)));
-       mem->list = NULL;
-cleanup3:
-       swiotlb_cleanup();
-       return -ENOMEM;
 }
 
 void __init swiotlb_exit(void)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
+       struct io_tlb_mem *mem = io_tlb_default_mem;
+       size_t size;
 
-       if (!mem->orig_addr)
+       if (!mem)
                return;
 
-       if (mem->late_alloc) {
-               free_pages((unsigned long)mem->alloc_size,
-                          get_order(mem->nslabs * sizeof(size_t)));
-               free_pages((unsigned long)mem->orig_addr,
-                          get_order(mem->nslabs * sizeof(phys_addr_t)));
-               free_pages((unsigned long)mem->list,
-                          get_order(mem->nslabs * sizeof(int)));
-               free_pages((unsigned long)phys_to_virt(mem->start),
-                          get_order(mem->nslabs << IO_TLB_SHIFT));
-       } else {
-               memblock_free_late(__pa(mem->alloc_size),
-                                  PAGE_ALIGN(mem->nslabs * sizeof(size_t)));
-               memblock_free_late(__pa(mem->orig_addr),
-                                  PAGE_ALIGN(mem->nslabs * 
sizeof(phys_addr_t)));
-               memblock_free_late(__pa(mem->list),
-                                  PAGE_ALIGN(mem->nslabs * sizeof(int)));
-               memblock_free_late(mem->start,
-                                  PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT));
-       }
-       swiotlb_cleanup();
+       size = struct_size(mem, slots, mem->nslabs);
+       if (mem->late_alloc)
+               free_pages((unsigned long)mem, get_order(size));
+       else
+               memblock_free_late(__pa(mem), PAGE_ALIGN(size));
+       io_tlb_default_mem = NULL;
 }
 
 /*
@@ -435,10 +334,10 @@ void __init swiotlb_exit(void)
 static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t 
size,
                enum dma_data_direction dir)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
+       struct io_tlb_mem *mem = io_tlb_default_mem;
        int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT;
-       phys_addr_t orig_addr = mem->orig_addr[index];
-       size_t alloc_size = mem->alloc_size[index];
+       phys_addr_t orig_addr = mem->slots[index].orig_addr;
+       size_t alloc_size = mem->slots[index].alloc_size;
        unsigned long pfn = PFN_DOWN(orig_addr);
        unsigned char *vaddr = phys_to_virt(tlb_addr);
 
@@ -517,7 +416,7 @@ static unsigned int wrap_index(struct io_tlb_mem *mem, 
unsigned int index)
 static int find_slots(struct device *dev, phys_addr_t orig_addr,
                size_t alloc_size)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
+       struct io_tlb_mem *mem = io_tlb_default_mem;
        unsigned long boundary_mask = dma_get_seg_boundary(dev);
        dma_addr_t tbl_dma_addr =
                phys_to_dma_unencrypted(dev, mem->start) & boundary_mask;
@@ -559,7 +458,7 @@ static int find_slots(struct device *dev, phys_addr_t 
orig_addr,
                if (!iommu_is_span_boundary(index, nslots,
                                            nr_slots(tbl_dma_addr),
                                            max_slots)) {
-                       if (mem->list[index] >= nslots)
+                       if (mem->slots[index].list >= nslots)
                                goto found;
                }
                index = wrap_index(mem, index + stride);
@@ -571,11 +470,11 @@ static int find_slots(struct device *dev, phys_addr_t 
orig_addr,
 
 found:
        for (i = index; i < index + nslots; i++)
-               mem->list[i] = 0;
+               mem->slots[i].list = 0;
        for (i = index - 1;
             io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 &&
-            mem->list[i]; i--)
-               mem->list[i] = ++count;
+            mem->slots[i].list; i--)
+               mem->slots[i].list = ++count;
 
        /*
         * Update the indices to avoid searching in the next round.
@@ -594,12 +493,12 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, 
phys_addr_t orig_addr,
                size_t mapping_size, size_t alloc_size,
                enum dma_data_direction dir, unsigned long attrs)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
+       struct io_tlb_mem *mem = io_tlb_default_mem;
        unsigned int offset = swiotlb_align_offset(dev, orig_addr);
        unsigned int index, i;
        phys_addr_t tlb_addr;
 
-       if (no_iotlb_memory)
+       if (!mem)
                panic("Can not allocate SWIOTLB buffer earlier and can't now 
provide you with the DMA bounce buffer");
 
        if (mem_encrypt_active())
@@ -626,8 +525,9 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, 
phys_addr_t orig_addr,
         * needed.
         */
        for (i = 0; i < nr_slots(alloc_size + offset); i++) {
-               mem->orig_addr[index + i] = slot_addr(orig_addr, i);
-               mem->alloc_size[index + i] = alloc_size - (i << IO_TLB_SHIFT);
+               mem->slots[index + i].orig_addr = slot_addr(orig_addr, i);
+               mem->slots[index + i].alloc_size =
+                       alloc_size - (i << IO_TLB_SHIFT);
        }
        tlb_addr = slot_addr(mem->start, index) + offset;
        if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
@@ -643,11 +543,11 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
phys_addr_t tlb_addr,
                              size_t mapping_size, enum dma_data_direction dir,
                              unsigned long attrs)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
+       struct io_tlb_mem *mem = io_tlb_default_mem;
        unsigned long flags;
        unsigned int offset = swiotlb_align_offset(hwdev, tlb_addr);
        int index = (tlb_addr - offset - mem->start) >> IO_TLB_SHIFT;
-       int nslots = nr_slots(mem->alloc_size[index] + offset);
+       int nslots = nr_slots(mem->slots[index].alloc_size + offset);
        int count, i;
 
        /*
@@ -665,7 +565,7 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
phys_addr_t tlb_addr,
         */
        spin_lock_irqsave(&mem->lock, flags);
        if (index + nslots < ALIGN(index + 1, IO_TLB_SEGSIZE))
-               count = mem->list[index + nslots];
+               count = mem->slots[index + nslots].list;
        else
                count = 0;
 
@@ -674,9 +574,9 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
phys_addr_t tlb_addr,
         * superceeding slots
         */
        for (i = index + nslots - 1; i >= index; i--) {
-               mem->list[i] = ++count;
-               mem->orig_addr[i] = INVALID_PHYS_ADDR;
-               mem->alloc_size[i] = 0;
+               mem->slots[i].list = ++count;
+               mem->slots[i].orig_addr = INVALID_PHYS_ADDR;
+               mem->slots[i].alloc_size = 0;
        }
 
        /*
@@ -684,9 +584,9 @@ void swiotlb_tbl_unmap_single(struct device *hwdev, 
phys_addr_t tlb_addr,
         * available (non zero)
         */
        for (i = index - 1;
-            io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 && mem->list[i];
+            io_tlb_offset(i) != IO_TLB_SEGSIZE - 1 && mem->slots[i].list;
             i--)
-               mem->list[i] = ++count;
+               mem->slots[i].list = ++count;
        mem->used -= nslots;
        spin_unlock_irqrestore(&mem->lock, flags);
 }
@@ -750,19 +650,17 @@ size_t swiotlb_max_mapping_size(struct device *dev)
 
 bool is_swiotlb_active(void)
 {
-       /*
-        * When SWIOTLB is initialized, even if mem->start points to physical
-        * address zero, mem->end surely doesn't.
-        */
-       return io_tlb_default_mem.end != 0;
+       return io_tlb_default_mem != NULL;
 }
 
 #ifdef CONFIG_DEBUG_FS
 
 static int __init swiotlb_create_debugfs(void)
 {
-       struct io_tlb_mem *mem = &io_tlb_default_mem;
+       struct io_tlb_mem *mem = io_tlb_default_mem;
 
+       if (!mem)
+               return 0;
        mem->debugfs = debugfs_create_dir("swiotlb", NULL);
        debugfs_create_ulong("io_tlb_nslabs", 0400, mem->debugfs, &mem->nslabs);
        debugfs_create_ulong("io_tlb_used", 0400, mem->debugfs, &mem->used);
-- 
2.29.2




 


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