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 <petr.pisar@xxxxxxxx> Bisected-by: Tom Li <biergaizi2009@xxxxxxxxx> Reported-and-tested-by: Tom Li <biergaizi2009@xxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Stanislaw Gruszka <stf_xl@xxxxx> --- drivers/net/wireless/rtl818x/rtl8187/rtl8187.h | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/rtl818x/rtl8187/rtl8187.h b/drivers/net/wireless/rtl818x/rtl8187/rtl8187.h index 56aee06..a6ad79f 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 <linux/cache.h> + #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; }; -- 1.7.4.4
