linux-kernel - [PATCH] mailbox: always wait in mbox_send

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Date:   Mon, 20 Mar 2017 15:40:10 +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] mailbox: always wait in mbox_send_message for blocking tx mode

There exists a race when msg_submit return immediately as there was an
active request being processed which may have completed just before it's
checked again in mbox_send_message. This will result in return to the
caller without waiting in mbox_send_message even when it's blocking Tx.

This patch fixes the issue by making use of non-negative token returned
by add_to_rbuf to check if the request was queued and block always if
so in blocking Tx mode.

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 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 4671f8a12872..d5895791ab5d 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -260,7 +260,7 @@ int mbox_send_message(struct mbox_chan *chan, void *mssg)
 
 	msg_submit(chan);
 
-	if (chan->cl->tx_block && chan->active_req) {
+	if (chan->cl->tx_block && t >= 0) {
 		unsigned long wait;
 		int ret;
 
-- 
2.7.4