linux-kernel - [PATCH 4.4 30/91] mailbox: skip complete wait event if timer expired

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Message-Id: <20170804231557.566636825@linuxfoundation.org>
Date:   Fri,  4 Aug 2017 16:15:26 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alexey Klimov <alexey.klimov@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Jassi Brar <jaswinder.singh@...aro.org>,
        Amit Pundir <amit.pundir@...aro.org>
Subject: [PATCH 4.4 30/91] mailbox: skip complete wait event if timer expired

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sudeep Holla <sudeep.holla@....com>

commit cc6eeaa3029a6dbcb4ad41b1f92876483bd88965 upstream.

If a wait_for_completion_timeout() call returns due to a timeout,
complete() can get called after returning from the wait which is
incorrect and can cause subsequent transmissions on a channel to fail.
Since the wait_for_completion_timeout() sees the completion variable
is non-zero caused by the erroneous/spurious complete() call, and
it immediately returns without waiting for the time as expected by the
client.

This patch fixes the issue by skipping complete() call for the timer
expiry.

Fixes: 2b6d83e2b8b7 ("mailbox: Introduce framework for mailbox")
Reported-by: Alexey Klimov <alexey.klimov@....com>
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Signed-off-by: Jassi Brar <jaswinder.singh@...aro.org>
Signed-off-by: Amit Pundir <amit.pundir@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/mailbox/mailbox.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -108,7 +108,7 @@ static void tx_tick(struct mbox_chan *ch
 	if (mssg && chan->cl->tx_done)
 		chan->cl->tx_done(chan->cl, mssg, r);
 
-	if (chan->cl->tx_block)
+	if (r != -ETIME && chan->cl->tx_block)
 		complete(&chan->tx_complete);
 }
 
@@ -272,8 +272,8 @@ int mbox_send_message(struct mbox_chan *
 
 		ret = wait_for_completion_timeout(&chan->tx_complete, wait);
 		if (ret == 0) {
-			t = -EIO;
-			tx_tick(chan, -EIO);
+			t = -ETIME;
+			tx_tick(chan, t);
 		}
 	}