Messages in this thread | | | Subject | Re: USB mass storage and ARM cache coherency | From | Catalin Marinas <> | Date | Fri, 26 Feb 2010 16:00:44 +0000 |
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On Wed, 2010-02-24 at 21:13 +0000, Benjamin Herrenschmidt wrote: > On Wed, 2010-02-24 at 11:19 -0500, Alan Stern wrote: > > > It is but I'm not confident the responsibility for doing that cleanup > > > is at the HCD level. That would impact a lot of HCD activities that > > > don't need such flushing since the use of the page is purely in-kernel. > > > > That's right. The HCD merely puts data wherever it's told to. It > > doesn't know whether the destination is in the page cache, in > > userspace, or anywhere else. The same is true for usb-storage. > > I'm surprised that usb-storage has an issue here. It shouldn't afaik, > since it's just a SCSI driver (or not anymore ?) and the BIO or > filesystems handle things there no ? I haven't seen a single call to > flush_dcache_page() in any of drivers/scsi, drivers/ata or drivers/ide > when I looked...
The BIO or filesystem code don't call flush_dcache_page() either (well some do like cramfs or jffs but they decompress the data received from the block device).
-- Catalin
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