[PATCH v2] drivers: net: xgene: fix: Out of order descriptor bytes read

[David Miller]

From: Iyappan Subramanian <isubramanian at apm.com>
Date: Thu, 29 Jan 2015 14:38:23 -0800

> This patch fixes the following kernel crash,
 ...
> Software writes poison data into the descriptor bytes[15:8] and upon
> receiving the interrupt, if those bytes are overwritten by the hardware with
> the valid data, software also reads bytes[7:0] and executes receive/tx
> completion logic.
> 
> If the CPU executes the above two reads in out of order fashion, then the
> bytes[7:0] will have older data and causing the kernel panic.  We have to
> force the order of the reads and thus this patch introduces read memory
> barrier between these reads.
> 
> Signed-off-by: Iyappan Subramanian <isubramanian at apm.com>
> Signed-off-by: Keyur Chudgar <kchudgar at apm.com>

Applied, thanks.