percpu: avoid calling __pcpu_ptr_to_addr(NULL)

__pcpu_ptr_to_addr() can be overridden by the architecture and might not behave well if passed a NULL pointer. So avoid calling it until we have verified that its arg is not NULL. Cc: Rusty Russell <[email protected]> Cc: Kamalesh Babulal <[email protected]> Acked-by: Tejun Heo <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
vbatts · Jan 11, 2010 · 129182e · 129182e
1 parent 8767ba2
commit 129182e
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/mm/percpu.c b/mm/percpu.c
@@ -1271,14 +1271,16 @@ static void pcpu_reclaim(struct work_struct *work)
  */
 void free_percpu(void *ptr)
 {
-	void *addr = __pcpu_ptr_to_addr(ptr);
+	void *addr;
 	struct pcpu_chunk *chunk;
 	unsigned long flags;
 	int off;
 
 	if (!ptr)
 		return;
 
+	addr = __pcpu_ptr_to_addr(ptr);
+
 	spin_lock_irqsave(&pcpu_lock, flags);
 
 	chunk = pcpu_chunk_addr_search(addr);