linux-kernel - [PATCHv3 4/6] mailbox: Fix TX completion init

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Date:	Sat, 15 Feb 2014 23:56:11 +0530
From:	Jassi Brar <jassisinghbrar@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	gregkh@...uxfoundation.org, s-anna@...com, tony@...mide.com,
	omar.ramirez@...itl.com, loic.pallardy@...com,
	lftan.linux@...il.com, slapdau@...oo.com.au,
	courtney.cavin@...ymobile.com, rafael.j.wysocki@...el.com,
	Jassi Brar <jaswinder.singh@...aro.org>
Subject: [PATCHv3 4/6] mailbox: Fix TX completion init

From: LeyFoon Tan <lftan.linux@...il.com>

For fast TX the complete could be called before being initialized as follows
 ipc_send_message --> poll_txdone --> tx_tick --> complete(&chan->tx_complete)

Init the completion early enough to fix the race.

Signed-off-by: LeyFoon Tan <lftan.linux@...il.com>
Signed-off-by: Jassi Brar <jaswinder.singh@...aro.org>
---
 drivers/mailbox/mailbox.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 3082f08..f8b31da 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -258,6 +258,9 @@ request_token_t ipc_send_message(void *channel, void *mssg)
 	if (!chan || !chan->assigned)
 		return 0;
 
+	if (chan->tx_block)
+		init_completion(&chan->tx_complete);
+
 	t = _add_to_rbuf(chan, mssg);
 	if (!t)
 		pr_err("Try increasing MBOX_TX_QUEUE_LEN\n");
@@ -269,7 +272,6 @@ request_token_t ipc_send_message(void *channel, void *mssg)
 
 	if (chan->tx_block && chan->active_req) {
 		int ret;
-		init_completion(&chan->tx_complete);
 		ret = wait_for_completion_timeout(&chan->tx_complete,
 			chan->tx_tout);
 		if (ret == 0) {
-- 
1.8.1.2

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