Messages in this thread Patch in this message | | | Date | Tue, 16 Dec 2014 11:36:02 +0000 | From | Sudeep Holla <> | Subject | Re: [Linaro-acpi] [PATCH] Mailbox: Complete wait event only if Tx was successful |
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On Fri, Dec 12, 2014 at 05:47:26PM +0000, Ashwin Chaugule wrote: > On 12 December 2014 at 03:43, Sudeep Holla <sudeep.holla@arm.com> wrote: > > Hi Ashwin, > > Hi, >
Hi Ashwin,
> > 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 !
Regards, Sudeep
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