linux-kernel - [PATCH 2/3] mailbox: skip complete wait event if timer expired

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Date:   Tue, 21 Mar 2017 11:30:15 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     linux-kernel@...r.kernel.org,
        Jassi Brar <jaswinder.singh@...aro.org>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Alexey Klimov <alexey.klimov@....com>,
        Jassi Brar <jassisinghbrar@...il.com>
Subject: [PATCH 2/3] mailbox: skip complete wait event if timer expired

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")
Cc: Jassi Brar <jassisinghbrar@...il.com>
Reported-by: Alexey Klimov <alexey.klimov@....com>
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
---
 drivers/mailbox/mailbox.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 160d6640425a..2ed7fa681ecb 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -107,7 +107,7 @@ 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 != -ETIME && chan->cl->tx_block)
 		complete(&chan->tx_complete);
 }
 
@@ -271,8 +271,8 @@ int mbox_send_message(struct mbox_chan *chan, void *mssg)
 
 		ret = wait_for_completion_timeout(&chan->tx_complete, wait);
 		if (ret == 0) {
-			t = -EIO;
-			tx_tick(chan, -EIO);
+			t = -ETIME;
+			tx_tick(chan, t);
 		}
 	}
 
-- 
2.7.4