arch/unicore32/mm/ioremap.c: return NULL on invalid pfn

__uc32_ioremap_pfn_caller() should return NULL when the pfn is found to be
invalid.

From a recommendation by Guan Xuetao.

Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/arch/unicore32/mm/ioremap.c b/arch/unicore32/mm/ioremap.c
index a0840fa05431..bf012b2b71a9 100644
--- a/arch/unicore32/mm/ioremap.c
+++ b/arch/unicore32/mm/ioremap.c
@@ -143,11 +143,13 @@ void __iomem *__uc32_ioremap_pfn_caller(unsigned long pfn,
         /*
          * Don't allow RAM to be mapped
          */
-        if (pfn_valid(pfn))
+        if (pfn_valid(pfn)) {
                 WARN(1, "BUG: Your driver calls ioremap() on\n"
                         "system memory.  This leads to architecturally\n"
                         "unpredictable behaviour, and ioremap() will fail in\n"
                         "the next kernel release. Please fix your driver.\n");
+                return NULL;
+        }
 
         type = get_mem_type(mtype);
         if (!type)