diff options
-rw-r--r-- | arch/s390/mm/gup.c | 81 |
1 files changed, 23 insertions, 58 deletions
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c index 5d758db..d3a2b81 100644 --- a/arch/s390/mm/gup.c +++ b/arch/s390/mm/gup.c @@ -182,7 +182,13 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, end = start + len; 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; } |