4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Huacai Chen chenhc@lemote.com
commit 18f3e95b90b28318ef35910d21c39908de672331 upstream.
While a barrier is present in the outX() functions before the register write, a similar barrier is missing in the inX() functions after the register read. This could allow memory accesses following inX() to observe stale data.
This patch is very similar to commit a1cc7034e33d12dc1 ("MIPS: io: Add barrier after register read in readX()"). Because war_io_reorder_wmb() is both used by writeX() and outX(), if readX() need a barrier then so does inX().
Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen chenhc@lemote.com Patchwork: https://patchwork.linux-mips.org/patch/19516/ Signed-off-by: Paul Burton paul.burton@mips.com Cc: James Hogan james.hogan@mips.com Cc: linux-mips@linux-mips.org Cc: Fuxin Zhang zhangfx@lemote.com Cc: Zhangjin Wu wuzhangjin@gmail.com Cc: Huacai Chen chenhuacai@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/mips/include/asm/io.h | 2 ++ 1 file changed, 2 insertions(+)
--- a/arch/mips/include/asm/io.h +++ b/arch/mips/include/asm/io.h @@ -411,6 +411,8 @@ static inline type pfx##in##bwlq##p(unsi __val = *__addr; \ slow; \ \ + /* prevent prefetching of coherent DMA data prematurely */ \ + rmb(); \ return pfx##ioswab##bwlq(__addr, __val); \ }