[PATCH v2 1/4] mm/gup: move __get_user_pages_fast() down a few lines in gup.c

John Hubbard
2020-05-22T05:19:39Z

This is in order to avoid a forward declaration of
internal_get_user_pages_fast(), in the next patch.

This is code movement only--all generated code should
be identical.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
mm/gup.c | 112 +++++++++++++++++++++++++++----------------------------
1 file changed, 56 insertions(+), 56 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 50cd9323efff..4502846d57f9 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2666,62 +2666,6 @@ static bool gup_fast_permitted(unsigned long start, unsigned long end)
}
#endif

-/*
- * Like get_user_pages_fast() except it's IRQ-safe in that it won't fall back to
- * the regular GUP.
- * Note a difference with get_user_pages_fast: this always returns the
- * number of pages pinned, 0 if no pages were pinned.
- *
- * If the architecture does not support this function, simply return with no
- * pages pinned.
- */
-int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
- struct page **pages)
-{
- unsigned long len, end;
- unsigned long flags;
- int nr_pinned = 0;
- /*
- * Internally (within mm/gup.c), gup fast variants must set FOLL_GET,
- * because gup fast is always a "pin with a +1 page refcount" request.
- */
- unsigned int gup_flags = FOLL_GET;
-
- if (write)
- gup_flags |= FOLL_WRITE;
-
- start = untagged_addr(start) & PAGE_MASK;
- len = (unsigned long) nr_pages << PAGE_SHIFT;
- end = start + len;
-
- if (end <= start)
- return 0;
- if (unlikely(!access_ok((void __user *)start, len)))
- return 0;
-
- /*
- * Disable interrupts. We use the nested form as we can already have
- * interrupts disabled by get_futex_key.
- *
- * With interrupts disabled, we block page table pages from being
- * freed from under us. See struct mmu_table_batch comments in
- * include/asm-generic/tlb.h for more details.
- *
- * We do not adopt an rcu_read_lock(.) here as we also want to
- * block IPIs that come from THPs splitting.
- */
-
- if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) &&
- gup_fast_permitted(start, end)) {
- local_irq_save(flags);
- gup_pgd_range(start, end, gup_flags, pages, &nr_pinned);
- local_irq_restore(flags);
- }
-
- return nr_pinned;
-}
-EXPORT_SYMBOL_GPL(__get_user_pages_fast);
-
static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
unsigned int gup_flags, struct page **pages)
{
@@ -2794,6 +2738,62 @@ static int internal_get_user_pages_fast(unsigned long start, int nr_pages,
return ret;
}

+/*
+ * Like get_user_pages_fast() except it's IRQ-safe in that it won't fall back to
+ * the regular GUP.
+ * Note a difference with get_user_pages_fast: this always returns the
+ * number of pages pinned, 0 if no pages were pinned.
+ *
+ * If the architecture does not support this function, simply return with no
+ * pages pinned.
+ */
+int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
+ struct page **pages)
+{
+ unsigned long len, end;
+ unsigned long flags;
+ int nr_pinned = 0;
+ /*
+ * Internally (within mm/gup.c), gup fast variants must set FOLL_GET,
+ * because gup fast is always a "pin with a +1 page refcount" request.
+ */
+ unsigned int gup_flags = FOLL_GET;
+
+ if (write)
+ gup_flags |= FOLL_WRITE;
+
+ start = untagged_addr(start) & PAGE_MASK;
+ len = (unsigned long) nr_pages << PAGE_SHIFT;
+ end = start + len;
+
+ if (end <= start)
+ return 0;
+ if (unlikely(!access_ok((void __user *)start, len)))
+ return 0;
+
+ /*
+ * Disable interrupts. We use the nested form as we can already have
+ * interrupts disabled by get_futex_key.
+ *
+ * With interrupts disabled, we block page table pages from being
+ * freed from under us. See struct mmu_table_batch comments in
+ * include/asm-generic/tlb.h for more details.
+ *
+ * We do not adopt an rcu_read_lock(.) here as we also want to
+ * block IPIs that come from THPs splitting.
+ */
+
+ if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) &&
+ gup_fast_permitted(start, end)) {
+ local_irq_save(flags);
+ gup_pgd_range(start, end, gup_flags, pages, &nr_pinned);
+ local_irq_restore(flags);
+ }
+
+ return nr_pinned;
+}
+EXPORT_SYMBOL_GPL(__get_user_pages_fast);
+
/**
* get_user_pages_fast() - pin user pages in memory
* @start: starting user address
--
2.26.2