On 12 December 2014 at 05:21, Jassi Brar <jaswinder.si...@linaro.org> wrote: > 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).
If the controller returned error, wouldnt it be passed to the user via chan->cl->tx_done()? However, I agree that with this fix, it won't call complete(), when the controller finished the Tx with an Err. > 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. Hm. How about checking if the wait_for_completion_timeout() returned the timeout value? If so, then return with -EIO and don't complete(). > > -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/
