linux-4.4.1/cma_alloc() の変更点

• 追加された行はこの色です。
• 削除された行はこの色です。
• linux-4.4.1/cma_alloc() へ行く。
• linux-4.4.1/cma_alloc() の差分を削除

*参照元 [#k36c4542]
#backlinks

*説明 [#x060ae1a]
-パス: [[linux-4.4.1/mm/cma.c]]

-FIXME: これは何？
--説明


**引数 [#m2ca9094]
-struct cma *cma
--
--[[linux-4.4.1/cma]]
-size_t count
--
-unsigned int align
--


**返り値 [#k5d5a970]
-struct page *
--
--[[linux-4.4.1/page]]


**参考 [#te23a298]


*実装 [#h0e93adc]
 /**
  * cma_alloc() - allocate pages from contiguous area
  * @cma:   Contiguous memory region for which the allocation is performed.
  * @count: Requested number of pages.
  * @align: Requested alignment of pages (in PAGE_SIZE order).
  *
  * This function allocates part of contiguous memory on specific
  * contiguous memory area.
  */
 struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align)
 {
         unsigned long mask, offset;
         unsigned long pfn = -1;
         unsigned long start = 0;
         unsigned long bitmap_maxno, bitmap_no, bitmap_count;
         struct page *page = NULL;
         int ret;
 
         if (!cma || !cma->count)
                 return NULL;
 
         pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
                  count, align);
 
-
--[[linux-4.4.1/pr_debug()]]

         if (!count)
                 return NULL;
 
         mask = cma_bitmap_aligned_mask(cma, align);
         offset = cma_bitmap_aligned_offset(cma, align);
         bitmap_maxno = cma_bitmap_maxno(cma);
         bitmap_count = cma_bitmap_pages_to_bits(cma, count);
 
-
--[[linux-4.4.1/cma_bitmap_aligned_mask()]]
--[[linux-4.4.1/cma_bitmap_aligned_offset()]]
--[[linux-4.4.1/cma_bitmap_maxno()]]
--[[linux-4.4.1/cma_bitmap_pages_to_bits()]]

         for (;;) {
                 mutex_lock(&cma->lock);
                 bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
                                 bitmap_maxno, start, bitmap_count, mask,
                                 offset);
-
--[[linux-4.4.1/mutex_lock()]]
--[[linux-4.4.1/bitmap_find_next_zero_area_off()]]

                 if (bitmap_no >= bitmap_maxno) {
                         mutex_unlock(&cma->lock);
                         break;
                 }
                 bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
-
--[[linux-4.4.1/mutex_unlock()]]
--[[linux-4.4.1/bitmap_set()]]

                 /*
                  * It's safe to drop the lock here. We've marked this region for
                  * our exclusive use. If the migration fails we will take the
                  * lock again and unmark it.
                  */
                 mutex_unlock(&cma->lock);
 
                 pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
                 mutex_lock(&cma_mutex);
                 ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
                 mutex_unlock(&cma_mutex);
-
--[[linux-4.4.1/alloc_contig_range()]]
--[[linux-4.4.1/MIGRATE_CMA]]

                 if (ret == 0) {
                         page = pfn_to_page(pfn);
                         break;
                 }
 
-
--[[linux-4.4.1/pfn_to_page()]]

                 cma_clear_bitmap(cma, pfn, count);
                 if (ret != -EBUSY)
                         break;
 
-
--[[linux-4.4.1/cma_clear_bitmap()]]

                 pr_debug("%s(): memory range at %p is busy, retrying\n",
                          __func__, pfn_to_page(pfn));
                 /* try again with a bit different memory target */
                 start = bitmap_no + mask + 1;
         }
 
         trace_cma_alloc(pfn, page, count, align);
 
-
--[[linux-4.4.1/trace_cma_alloc()]]

         pr_debug("%s(): returned %p\n", __func__, page);
         return page;
 }


*コメント [#o7fb96ad]