USB mass storage and ARM cache coherency
From: catalin.marinas@arm.com (Catalin Marinas)
Date: 2010-02-26 16:00:53
Also in:
lkml
On Wed, 2010-02-24 at 21:13 +0000, Benjamin Herrenschmidt wrote:
On Wed, 2010-02-24 at 11:19 -0500, Alan Stern wrote:quoted
quoted
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