Hi, On Fri, Feb 03, 2012 at 04:43:20PM +0100, Guennadi Liakhovetski wrote: > The current renesas_usbhs driver triggers > > BUG: scheduling while atomic: ksoftirqd/0/3/0x00000102 > > with enabled CONFIG_DEBUG_ATOMIC_SLEEP, by submitting DMA transfers from > an atomic (tasklet) context, which is not supported by the shdma dmaengine > driver. Fix it by switching to a work. Also simplify some list > manipulations. you are doing much more than what you say. Also, instead of using a workqueue, have you considered using threaded_irqs ? (I didn't go over the driver again to see if it makes sense to use threaded_irqs in this case, but doesn't hurt asking) > Shimoda-san, this is the problem, that you were observing. However, it > exists with the present version of shdma just as well as with the new one > - on top of the simple DMA library. I marked it an RFC because (1) I only > lightly tested it with the gadget device on mackerel with the mass storage > gadget, and (2) I am somewhat concerned about races. Currently the work > function runs with no locking and there are no usual cancel_work_sync() > points in the patch. However, it has also been like this before with the > tasklet implementation, which is not much better, and it looks like there > are no asynchronous operations on the same packets like timeouts. Only > asynchronous events, that I can think about are things like unloading the > driver or unplugging the cable, but these have been there before too. It > would become worse on SMP, I think. Comments welcome. > > diff --git a/drivers/usb/renesas_usbhs/fifo.c b/drivers/usb/renesas_usbhs/fifo.c > index 72339bd..4d739ec 100644 > --- a/drivers/usb/renesas_usbhs/fifo.c > +++ b/drivers/usb/renesas_usbhs/fifo.c > @@ -75,8 +75,7 @@ void usbhs_pkt_push(struct usbhs_pipe *pipe, struct usbhs_pkt *pkt, > pipe->handler = &usbhsf_null_handler; > } > > - list_del_init(&pkt->node); > - list_add_tail(&pkt->node, &pipe->list); > + list_move_tail(&pkt->node, &pipe->list); > > /* > * each pkt must hold own handler. > @@ -106,7 +105,7 @@ static struct usbhs_pkt *__usbhsf_pkt_get(struct usbhs_pipe *pipe) > if (list_empty(&pipe->list)) > return NULL; > > - return list_entry(pipe->list.next, struct usbhs_pkt, node); > + return list_first_entry(&pipe->list, struct usbhs_pkt, node); these two hunks are not part of $SUBJECT -- balbi
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