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Stanislaw Gruszka authored
This patch fixes regression caused by commit a16dad77 "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=54391Reported-by:
Petr Pisar <petr.pisar@atlas.cz> Bisected-by:
Tom Li <biergaizi2009@gmail.com> Reported-and-tested-by:
Tom Li <biergaizi2009@gmail.com> Cc: stable@vger.kernel.org Signed-off-by:
Stanislaw Gruszka <stf_xl@wp.pl> Acked-by:
Larry Finger <Larry.Finger@lwfinger.next> Acked-by:
Hin-Tak Leung <htl10@users.sourceforge.net> Signed-off-by:
John W. Linville <linville@tuxdriver.com>
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