[v3,07/11] mm: Remove definition of clear_bit_unlock_is_negative_byte

Commit Message

Matthew Wilcox (Oracle) April 16, 2020, 10:01 p.m. UTC

From: "Matthew Wilcox (Oracle)" <[e-mail]>

All architectures now have a definition of
clear_bit_unlock_is_negative_byte(), either their own or through
asm-generic/bitops/lock.h

Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
Reviewed-by: William Kucharski <[e-mail]>
---
 mm/filemap.c | 23 -----------------------
 1 file changed, 23 deletions(-)

Patch

diff --git a/mm/filemap.c b/mm/filemap.c
index 23a051a7ef0f..e475117e89eb 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1248,29 +1248,6 @@  void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter)
 }
 EXPORT_SYMBOL_GPL(add_page_wait_queue);
 
-#ifndef clear_bit_unlock_is_negative_byte
-
-/*
- * PG_waiters is the high bit in the same byte as PG_lock.
- *
- * On x86 (and on many other architectures), we can clear PG_lock and
- * test the sign bit at the same time. But if the architecture does
- * not support that special operation, we just do this all by hand
- * instead.
- *
- * The read of PG_waiters has to be after (or concurrently with) PG_locked
- * being cleared, but a memory barrier should be unneccssary since it is
- * in the same byte as PG_locked.
- */
-static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem)
-{
-	clear_bit_unlock(nr, mem);
-	/* smp_mb__after_atomic(); */
-	return test_bit(PG_waiters, mem);
-}
-
-#endif
-
 /**
  * unlock_page - unlock a locked page
  * @page: the page