[U-Boot] [PATCH v3] mips32: fix wrong loop bound in flush_cache()

[Yao Cheng <saturdaycoder@gmail.com>]

The issue is found when calling flush_cache() with zero "size" argument.
The bound of loop is miscalculated in this case and flush_cache() enters a wrong flushing loop.
To fix this issue I skipped the operations when "size" is found to be zero.

Signed-off-by: Yao Cheng <saturdaycoder@gmail.com>
Cc: Shinya Kuribayashi <skuribay@pobox.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: Mike Frysinger <vapier@gentoo.org>
---
Changes for v2:
	- Coding style cleanup
	- Move code after declarations to avoid warning
Changes for v3:
	- Coding style cleanup
	- Add prefix "mips32" to the subject

 arch/mips/cpu/mips32/cpu.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/mips/cpu/mips32/cpu.c b/arch/mips/cpu/mips32/cpu.c
index 3ae397c..7b49e1b 100644
--- a/arch/mips/cpu/mips32/cpu.c
+++ b/arch/mips/cpu/mips32/cpu.c
@@ -56,6 +56,10 @@ void flush_cache(ulong start_addr, ulong size)
 	unsigned long addr = start_addr & ~(lsize - 1);
 	unsigned long aend = (start_addr + size - 1) & ~(lsize - 1);
 
+	/* aend will be miscalculated when size is zero, so we return here */
+	if (size == 0)
+		return;
+
 	while (1) {
 		cache_op(Hit_Writeback_Inv_D, addr);
 		cache_op(Hit_Invalidate_I, addr);
-- 
1.7.4.1