Fix zero length sys_cacheflush

    
Cacheflush(0, 0, 0) was crashing the system.  This is because
flush_icache_range(start, end) tries to flushing whole address space
(0 - ~0UL) if both start and end are zero.
    
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
index 611b48dde737..314701a66b13 100644
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -56,6 +56,8 @@ EXPORT_SYMBOL(_dma_cache_inv);
 asmlinkage int sys_cacheflush(unsigned long __user addr,
         unsigned long bytes, unsigned int cache)
 {
+        if (bytes == 0)
+                return 0;
         if (!access_ok(VERIFY_WRITE, (void __user *) addr, bytes))
                 return -EFAULT;