Your patch add rmb() before read in readX(), why inX() need rmb() after read?
Huacai
On Mon, Apr 23, 2018 at 12:31 PM, okaya@codeaurora.org wrote:
On 2018-04-22 23:53, Huacai Chen wrote:
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
arch/mips/include/asm/io.h | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h index a7d0b83..cea8ad8 100644 --- a/arch/mips/include/asm/io.h +++ b/arch/mips/include/asm/io.h @@ -414,6 +414,8 @@ static inline type pfx##in##bwlq##p(unsigned long port) \ __val = *__addr; \ slow; \ \
/* prevent prefetching of coherent DMA data prematurely */ \rmb(); \ return pfx##ioswab##bwlq(__addr, __val); \}
Typically read barrier is applied after register read.