On Thu, Apr 06, 2017 at 10:45:26PM +0530, Jassi Brar wrote: > On 6 April 2017 at 22:28, Alexey Klimov <alexey.kli...@arm.com> wrote: > > Hi Jassi/Sudeep, > > > > On Wed, Mar 29, 2017 at 07:01:09PM +0100, Sudeep Holla wrote: > >> > >> > >> On 29/03/17 18:43, Jassi Brar wrote: > ... > > >> > diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c > >> > index 9dfbf7e..e06c50c 100644 > >> > --- a/drivers/mailbox/mailbox.c > >> > +++ b/drivers/mailbox/mailbox.c > >> > @@ -41,6 +41,7 @@ static int add_to_rbuf(struct mbox_chan *chan, void > >> > *mssg) > >> > > >> > idx = chan->msg_free; > >> > chan->msg_data[idx] = mssg; > >> > + init_completion(&chan->tx_cmpl[idx]); > >> > >> reinit would be better. > > > Of course. > > .... > > From: Alexey Klimov <alexey.kli...@arm.com> > > Date: Thu, 6 Apr 2017 13:57:02 +0100 > > Subject: [RFC][PATCH] mailbox: per-channel arrays with msg data and > > completion > > structures > > > > When a mailbox client doesn't serialize sending of the message itself, > > and asks mailbox framework to block on mbox_send_message(), one > > completion structure per channel is not enough. Client can make a few > > mbox_send_message() calls at the same time, and there is no guaranteed > > order of going to sleep on completion. > > > > If mailbox controller acks a message transfer, then tx_tick() wakes up > > the first thread that waits on completion. > > If mailbox controller doesn't ack the transfer and timeout happens, then > > tx_tick() calls complete, and the next caller trying to sleep on > > completion wakes up immediately. > > > > This patch fixes this by changing completion structures to be inserted > > into an array that contains a) pointer to data provided by client and > > b) the completion structure. Thus active_req field tracks the index of > > the current running request that was submitted to mailbox controller. > > > > Signed-off-by: Alexey Klimov <alexey.kli...@arm.com> > > --- > > drivers/mailbox/mailbox.c | 40 > > +++++++++++++++++++++++--------------- > > drivers/mailbox/pcc.c | 10 +++++++--- > > include/linux/mailbox_controller.h | 24 +++++++++++++++++------ > ... > > 3 files changed, 49 insertions(+), 25 deletions(-) > > > Versus 4 files changed, 17 insertions(+), 8 deletions(-) > > I think we should just keep it simpler if it works just as fine.
Along with this patch you still need at least one patch from Sudeep with subject: "[PATCH 1/3] mailbox: always wait in mbox_send_message for blocking Tx mode" Decision to block or not shouldn't depend on racy reading of active_req field. Best regards, Alexey Klimov.
