memblock, x86: Reimplement memblock_find_dma_reserve() using iterators

memblock_find_dma_reserve() wants to find out how much memory is
reserved under MAX_DMA_PFN.  memblock_x86_memory_[free_]in_range() are
used to find out the amounts of all available and free memory in the
area, which are then subtracted to find out the amount of reservation.

memblock_x86_memblock_[free_]in_range() are implemented using
__memblock_x86_memory_in_range() which builds ranges from memblock and
then count them, which is rather unnecessarily complex.

This patch open codes the counting logic directly in
memblock_find_dma_reserve() using memblock iterators and removes now
unused __memblock_x86_memory_in_range() and find_range_array().

Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1310462166-31469-11-git-send-email-tj@kernel.org
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 20 insertions, 5 deletions

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index b99d9402ae8b..84475f1e2201 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -1093,15 +1093,30 @@ void __init memblock_x86_fill(void)
 void __init memblock_find_dma_reserve(void)
 {
 #ifdef CONFIG_X86_64
-        u64 free_size_pfn;
-        u64 mem_size_pfn;
+        u64 nr_pages = 0, nr_free_pages = 0;
+        unsigned long start_pfn, end_pfn;
+        phys_addr_t start, end;
+        int i;
+        u64 u;
+
         /*
          * need to find out used area below MAX_DMA_PFN
          * need to use memblock to get free size in [0, MAX_DMA_PFN]
          * at first, and assume boot_mem will not take below MAX_DMA_PFN
          */
-        mem_size_pfn = memblock_x86_memory_in_range(0, MAX_DMA_PFN << PAGE_SHIFT) >> PAGE_SHIFT;
-        free_size_pfn = memblock_x86_free_memory_in_range(0, MAX_DMA_PFN << PAGE_SHIFT) >> PAGE_SHIFT;
-        set_dma_reserve(mem_size_pfn - free_size_pfn);
+        for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
+                start_pfn = min_t(unsigned long, start_pfn, MAX_DMA_PFN);
+                end_pfn = min_t(unsigned long, end_pfn, MAX_DMA_PFN);
+                nr_pages += end_pfn - start_pfn;
+        }
+
+        for_each_free_mem_range(u, MAX_NUMNODES, &start, &end, NULL) {
+                start_pfn = min_t(unsigned long, PFN_UP(start), MAX_DMA_PFN);
+                end_pfn = min_t(unsigned long, PFN_DOWN(end), MAX_DMA_PFN);
+                if (start_pfn < end_pfn)
+                        nr_free_pages += end_pfn - start_pfn;
+        }
+
+        set_dma_reserve(nr_pages - nr_free_pages);
 #endif
 }