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Commit e5c2b83b authored by Lina Iyer's avatar Lina Iyer Committed by Deepak Kumar Singh
Browse files

drivers: mailbox: fix race resulting in multiple message submission 



The mailbox sends a request to the controller and the tx_done callback
received for that request clears the active_req pointer. The callback
sends the next request in the queue, if there is one. When a controller
is busy and cannot accept any more requests until the interrupt is
cleared, it would return -EAGAIN. The mailbox controller must unlock its
spinlock and retry again.

Change-Id: Id58c7365be8c6bfc7f90fe9445c88c1246d2d7f8
Signed-off-by: default avatarLina Iyer <ilina@codeaurora.org>
parent 84606f73

drivers/mailbox/mailbox.c

+19 −1
Original line number Diff line number Diff line
@@ -53,7 +53,7 @@ static int add_to_rbuf(struct mbox_chan *chan, void *mssg) 
	return idx;

}



static void msg_submit(struct mbox_chan *chan)

static int __msg_submit(struct mbox_chan *chan)

{

	unsigned count, idx;

	unsigned long flags;
@@ -85,6 +85,24 @@ static void msg_submit(struct mbox_chan *chan) 
exit:

	spin_unlock_irqrestore(&chan->lock, flags);



	return err;

}



static void msg_submit(struct mbox_chan *chan)

{

	int err = 0;



	/*

	 * If the controller returns -EAGAIN, then it means, our spinlock

	 * here is preventing the controller from receiving its interrupt,

	 * that would help clear the controller channels that are currently

	 * blocked waiting on the interrupt response.

	 * Retry again.

	 */

	do {

		err = __msg_submit(chan);

	} while (err == -EAGAIN);



	if (!err && (chan->txdone_method & TXDONE_BY_POLL))

		/* kick start the timer immediately to avoid delays */

		hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);