Nico Huber (nico.huber@secunet.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/1902
-gerrit
commit 7f59b31c4efaadebd2897b302c381b80f7925cab Author: Nico Huber nico.huber@secunet.com Date: Thu Nov 22 11:14:03 2012 +0100
libpayload: ehci: Prevent some race conditions
Prevent race conditions, when an interrupt-queue underrun occurred and the controller is currently working on our queue head or a transfer is still in progress.
Change-Id: Ia14f80a08071306ee5d1349780be081bfacb206a Signed-off-by: Nico Huber nico.huber@secunet.com --- payloads/libpayload/drivers/usb/ehci.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/payloads/libpayload/drivers/usb/ehci.c b/payloads/libpayload/drivers/usb/ehci.c index 4ff137e..6a1cfb5 100644 --- a/payloads/libpayload/drivers/usb/ehci.c +++ b/payloads/libpayload/drivers/usb/ehci.c @@ -626,8 +626,14 @@ static u8 *ehci_poll_intr_queue(void *const queue) intrq->head = intrq->head->next; } /* reset queue if we fully processed it after underrun */ - else if (intrq->qh.td.next_qtd & QTD_TERMINATE) { + else if ((intrq->qh.td.next_qtd & QTD_TERMINATE) && + /* to prevent race conditions: + not our head and not active */ + (intrq->qh.current_td_ptr != + virt_to_phys(&intrq->head->td)) && + !(intrq->qh.td.token & QTD_ACTIVE)) { usb_debug("resetting underrun ehci interrupt queue.\n"); + intrq->qh.current_td_ptr = 0; memset((void *)&intrq->qh.td, 0, sizeof(intrq->qh.td)); intrq->qh.td.next_qtd = virt_to_phys(&intrq->head->td); }