Merge remote-tracking branch 'hid/for-next'

[karo-tx-linux.git] / arch / s390 / mm / gup.c

diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
index 5d758db27bdced58d929d736363bcafc09c199ab..639fce464008854cf3d23c22f6dcbe4a970add68 100644 (file)
--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -180,9 +180,15 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
        addr = start;
        len = (unsigned long) nr_pages << PAGE_SHIFT;
        end = start + len;
-       if ((end < start) || (end > TASK_SIZE))
+       if ((end <= start) || (end > TASK_SIZE))
                return 0;
-
+       /*
+        * local_irq_save() doesn't prevent pagetable teardown, but does
+        * prevent the pagetables from being freed on s390.
+        *
+        * So long as we atomically load page table pointers versus teardown,
+        * we can follow the address down to the the page and take a ref on it.
+        */
        local_irq_save(flags);
        pgdp = pgd_offset(mm, addr);
        do {
@@ -219,63 +225,22 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
                        struct page **pages)
 {
        struct mm_struct *mm = current->mm;
-       unsigned long addr, len, end;
-       unsigned long next;
-       pgd_t *pgdp, pgd;
-       int nr = 0;
+       int nr, ret;
 
        start &= PAGE_MASK;
-       addr = start;
-       len = (unsigned long) nr_pages << PAGE_SHIFT;
-       end = start + len;
-       if ((end < start) || (end > TASK_SIZE))
-               goto slow_irqon;
-
-       /*
-        * local_irq_disable() doesn't prevent pagetable teardown, but does
-        * prevent the pagetables from being freed on s390.
-        *
-        * So long as we atomically load page table pointers versus teardown,
-        * we can follow the address down to the the page and take a ref on it.
-        */
-       local_irq_disable();
-       pgdp = pgd_offset(mm, addr);
-       do {
-               pgd = *pgdp;
-               barrier();
-               next = pgd_addr_end(addr, end);
-               if (pgd_none(pgd))
-                       goto slow;
-               if (!gup_pud_range(pgdp, pgd, addr, next, write, pages, &nr))
-                       goto slow;
-       } while (pgdp++, addr = next, addr != end);
-       local_irq_enable();
-
-       VM_BUG_ON(nr != (end - start) >> PAGE_SHIFT);
-       return nr;
-
-       {
-               int ret;
-slow:
-               local_irq_enable();
-slow_irqon:
-               /* Try to get the remaining pages with get_user_pages */
-               start += nr << PAGE_SHIFT;
-               pages += nr;
-
-               down_read(&mm->mmap_sem);
-               ret = get_user_pages(current, mm, start,
-                       (end - start) >> PAGE_SHIFT, write, 0, pages, NULL);
-               up_read(&mm->mmap_sem);
-
-               /* Have to be a bit careful with return values */
-               if (nr > 0) {
-                       if (ret < 0)
-                               ret = nr;
-                       else
-                               ret += nr;
-               }
-
-               return ret;
-       }
+       nr = __get_user_pages_fast(start, nr_pages, write, pages);
+       if (nr == nr_pages)
+               return nr;
+
+       /* Try to get the remaining pages with get_user_pages */
+       start += nr << PAGE_SHIFT;
+       pages += nr;
+       down_read(&mm->mmap_sem);
+       ret = get_user_pages(current, mm, start,
+                            nr_pages - nr, write, 0, pages, NULL);
+       up_read(&mm->mmap_sem);
+       /* Have to be a bit careful with return values */
+       if (nr > 0)
+               ret = (ret < 0) ? nr : ret + nr;
+       return ret;
 }