On 11 December 2014 at 01:46, Ashwin Chaugule <ashwin.chaug...@linaro.org> wrote: > If a wait_for_completion_timeout() call returns due to a timeout, > the mbox code can still call complete() after returning from the wait. > This can cause subsequent transmissions on a channel to fail, since > the wait_for_completion_timeout() sees the completion variable > is !=0, caused by the erroneous complete() call, and immediately > returns without waiting for the time as expected by the client. > > Fix this by calling complete() only if the TX was successful. > > Signed-off-by: Ashwin Chaugule <ashwin.chaug...@linaro.org> > --- > drivers/mailbox/mailbox.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c > index 17e9e4a..4acaddb 100644 > --- a/drivers/mailbox/mailbox.c > +++ b/drivers/mailbox/mailbox.c > @@ -101,7 +101,7 @@ static void tx_tick(struct mbox_chan *chan, int r) > if (mssg && chan->cl->tx_done) > chan->cl->tx_done(chan->cl, mssg, r); > > - if (chan->cl->tx_block) > + if ((!r) && chan->cl->tx_block) > complete(&chan->tx_complete); > Thanks for finding the bug. However the fix is flawed. complete() could also be done from mbox_chan_txdone() calling tx_tick(). And if the controller returned error, we could never pass on that error code to the user (timeout fires and then we will move on with -EIO). Since we could never prevent the controller from returning -EIO as the error, I think we have to explicitly tell tx_tick() if it needs to complete() or not.
-Jassi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
