On Thu, 25 Feb 2010, Benjamin Herrenschmidt wrote: > I'm surprised that usb-storage has an issue here. It shouldn't afaik, > since it's just a SCSI driver (or not anymore ?) It still is. There's also the ub driver, which is a non-SCSI block device driver for some of the same devices handled by usb-storage. > 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... There is no real issue; it's just that the problem was first noted in connection with usb-storage reading in executable pages, so Catalin's initial post was oriented toward modifying usb-storage. The main issue here is that the same host controller will use PIO sometimes and DMA sometimes, depending on the details of the transfer. The USB core didn't expect this and consequently we violated the rules for DMA mapping. The question is: If the core is fixed so that the rules aren't violated, will everything work correctly? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
