On Tue, Jun 11, 2013 at 4:51 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Mon, 10 Jun 2013, Alan Stern wrote: > >> > Tasklet doesn't disable local interrupts. >> >> It is documented that interrupts will be disabled while the completion >> handler runs. Therefore the tasklet _must_ disable local interrupts. > > You know, it may be that you can get most of the advantages you want by > enabling local interrupts around the call to unmap_urb_for_dma() in > usb_hcd_giveback_urb(). No, please don't enable IRQs inside interrupt handler, and you will get warning dump. Except for unmap_urb_for_dma() in usb_hcd_giveback_urb(), I hope map_urb_for_dma() inside complete() can benefit from the change too, since map_urb_for_dma() is same time-consuming with unmap_urb_for_dma(). Also I hope complete() can be run with interrupt enabled since driver's complete() may take long time on some ARCH, as I mentioned in my last mail. And it isn't good to disable interrupt only for one interface driver, looks I still don't get real good explanation about disabling IRQs here, :-) > > This may be a little dangerous, though, because it is possible for an > URB to be given back at the time it is submitted. Drivers may not > expect interrupts to get enabled temporarily when they call > usb_submit_urb(). Thanks, -- Ming Lei -- 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
