Messages in this thread | | | Date | Fri, 12 Dec 2014 12:47:26 -0500 | Subject | Re: [Linaro-acpi] [PATCH] Mailbox: Complete wait event only if Tx was successful | From | Ashwin Chaugule <> |
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On 12 December 2014 at 03:43, Sudeep Holla <sudeep.holla@arm.com> 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 <ashwin.chaugule@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); > > > 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
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