Am Dienstag, 22. März 2011, 14:08:17 schrieb Florian Mickler: > Am 22.03.2011 12:10 schrieb "Roedel, Joerg" <Joerg.Roedel@xxxxxxx>: > > > > On Mon, Mar 21, 2011 at 05:03:15PM -0400, Florian Mickler wrote: > > > I guess (not verified), that the dma api takes sufficient precautions > > > to abort the dma transfer if a timeout happens. So freeing _should_ > > > not be an issue. (At least, I would expect big fat warnings everywhere > > > if that were the case) > > > > Freeing is very well an issue. All you can expect from the DMA-API is to > > give you a valid DMA handle for your device. But it can not prevent that > > a device uses this handle after you returned it. You need to make sure > > yourself that any pending DMA is canceled before calling kfree(). > > Does usb_control_msg do this? It waits for completion but takes also a > timeout parameter. I will recheck this once I'm home. It uses usb_start_wait_urb() which upon a timeout kills the URB. The buffer is unused after usb_control_msg() returns. HTH Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
