From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754862AbaCYRVK (ORCPT ); Tue, 25 Mar 2014 13:21:10 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:55798 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753434AbaCYRVH (ORCPT ); Tue, 25 Mar 2014 13:21:07 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Stanislaw Gruszka , "John W. Linville" , Kamal Mostafa Subject: [PATCH 3.8 22/81] rtl8187: fix regression on MIPS without coherent DMA Date: Tue, 25 Mar 2014 10:15:35 -0700 Message-Id: <1395767794-5012-23-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1395767794-5012-1-git-send-email-kamal@canonical.com> References: <1395767794-5012-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8.13.20 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Stanislaw Gruszka commit b6213e413a4e0c66548153516b074df14f9d08e0 upstream. This patch fixes regression caused by commit a16dad77634 "MIPS: Fix potencial corruption". That commit fixes one corruption scenario in cost of adding another one, which actually start to cause crashes on Yeeloong laptop when rtl8187 driver is used. For correct DMA read operation on machines without DMA coherence, kernel have to invalidate cache, such it will refill later with new data that device wrote to memory, when that data is needed to process. We can only invalidate full cache line. Hence when cache line includes both dma buffer and some other data (written in cache, but not yet in main memory), the other data can not hit memory due to invalidation. That happen on rtl8187 where struct rtl8187_priv fields are located just before and after small buffers that are passed to USB layer and DMA is performed on them. To fix the problem we align buffers and reserve space after them to make them match cache line. This patch does not resolve all possible MIPS problems entirely, for that we have to assure that we always map cache aligned buffers for DMA, what can be complex or even not possible. But patch fixes visible and reproducible regression and seems other possible corruptions do not happen in practice, since Yeeloong laptop works stable without rtl8187 driver. Bug report: https://bugzilla.kernel.org/show_bug.cgi?id=54391 Reported-by: Petr Pisar Bisected-by: Tom Li Reported-and-tested-by: Tom Li Signed-off-by: Stanislaw Gruszka Acked-by: Larry Finger Acked-by: Hin-Tak Leung Signed-off-by: John W. Linville Signed-off-by: Kamal Mostafa --- drivers/net/wireless/rtl818x/rtl8187/rtl8187.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/rtl818x/rtl8187/rtl8187.h b/drivers/net/wireless/rtl818x/rtl8187/rtl8187.h index e19a20a..ecd1ac4 100644 --- a/drivers/net/wireless/rtl818x/rtl8187/rtl8187.h +++ b/drivers/net/wireless/rtl818x/rtl8187/rtl8187.h @@ -15,6 +15,8 @@ #ifndef RTL8187_H #define RTL8187_H +#include + #include "rtl818x.h" #include "leds.h" @@ -139,7 +141,10 @@ struct rtl8187_priv { u8 aifsn[4]; u8 rfkill_mask; struct { - __le64 buf; + union { + __le64 buf; + u8 dummy1[L1_CACHE_BYTES]; + } ____cacheline_aligned; struct sk_buff_head queue; } b_tx_status; /* This queue is used by both -b and non-b devices */ struct mutex io_mutex; @@ -147,7 +152,8 @@ struct rtl8187_priv { u8 bits8; __le16 bits16; __le32 bits32; - } *io_dmabuf; + u8 dummy2[L1_CACHE_BYTES]; + } *io_dmabuf ____cacheline_aligned; bool rfkill_off; u16 seqno; }; -- 1.8.3.2