On 12 December 2014 at 03:43, Sudeep Holla <[email protected]> wrote: > Hi Ashwin,
Hi, > On Thursday 11 December 2014 01:46 AM, Ashwin Chaugule 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 <[email protected]> >> --- >> 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); > > > Just curious to check if there's another possible race which is > a different issue. > > Suppose the timer fired and indicated that the Tx is complete, then > it tries to execute complete while the wait_for_completion_timeout timed > out. Does that make sense ? > > So if yes, how about adding !completion_done(..) to the check while you > are at this ? Yea. Seems like another race condition. I'll add it along with this.. Thanks, Ashwin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
