[Patch] rcu: remove dead code in include/linux/pagemap.h

Amerigo Wang
2011-01-31T06:27:50Z

TREE_RCU depends on !PREEMPT && SMP, when !CONFIG_SMP is true, CONFIG_TREE_RCU
will be false, thus "!defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)"
is always false.

Remove these dead code.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

---
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 9c66e99..e2bbbe3 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -133,23 +133,6 @@ static inline int page_cache_get_speculative(struct page *page)
{
VM_BUG_ON(in_interrupt());

-#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
-# ifdef CONFIG_PREEMPT
- VM_BUG_ON(!in_atomic());
-# endif
- /*
- * Preempt must be disabled here - we rely on rcu_read_lock doing
- * this for us.
- *
- * Pagecache won't be truncated from interrupt context, so if we have
- * found a page in the radix tree here, we have pinned its refcount by
- * disabling preempt, and hence no need for the "speculative get" that
- * SMP requires.
- */
- VM_BUG_ON(page_count(page) == 0);
- atomic_inc(&page->_count);
-
-#else
if (unlikely(!get_page_unless_zero(page))) {
/*
* Either the page has been freed, or will be freed.
@@ -158,7 +141,6 @@ static inline int page_cache_get_speculative(struct page *page)
*/
return 0;
}
-#endif
VM_BUG_ON(PageTail(page));

return 1;
@@ -171,17 +153,9 @@ static inline int page_cache_add_speculative(struct page *page, int count)
{
VM_BUG_ON(in_interrupt());

-#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
-# ifdef CONFIG_PREEMPT
- VM_BUG_ON(!in_atomic());
-# endif
- VM_BUG_ON(page_count(page) == 0);
- atomic_add(count, &page->_count);
-
-#else
if (unlikely(!atomic_add_unless(&page->_count, count, 0)))
return 0;
-#endif
+
VM_BUG_ON(PageCompound(page) && page != compound_head(page));

return 1;