linux-kernel - [PATCH testing] mrf24j40: Move INIT_COMPLETION to before the packet is sent

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Message-Id: <1369008316-16850-1-git-send-email-alan@signal11.us>
Date:	Sun, 19 May 2013 20:05:16 -0400
From:	Alan Ott <alan@...nal11.us>
To:	david@...weele.net
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-zigbee-devel@...ts.sourceforge.net,
	Alan Ott <alan@...nal11.us>
Subject: [PATCH testing] mrf24j40: Move INIT_COMPLETION to before the packet is sent

This avoids a race condition where the tx_complete interrupt could happen
before the completion is initialized.

---

David H,

Try this out and see if it changes anything for you. I put a bunch of
schedule_timeout()s in mrf24j40_tx() to basically guarantee that a reception
will happen during mrf24j40_tx(), and it seems to work. It would not work
before with said schedule_timeout() calls.

Alan.

---
 drivers/net/ieee802154/mrf24j40.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ieee802154/mrf24j40.c b/drivers/net/ieee802154/mrf24j40.c
index 556151d..0ea2a5a 100644
--- a/drivers/net/ieee802154/mrf24j40.c
+++ b/drivers/net/ieee802154/mrf24j40.c
@@ -345,6 +345,8 @@ static int mrf24j40_tx(struct ieee802154_dev *dev, struct sk_buff *skb)
 	if (ret)
 		goto err;
 
+	INIT_COMPLETION(devrec->tx_complete);
+
 	/* Set TXNTRIG bit of TXNCON to send packet */
 	ret = read_short_reg(devrec, REG_TXNCON, &val);
 	if (ret)
@@ -355,8 +357,6 @@ static int mrf24j40_tx(struct ieee802154_dev *dev, struct sk_buff *skb)
 		val |= 0x4;
 	write_short_reg(devrec, REG_TXNCON, val);
 
-	INIT_COMPLETION(devrec->tx_complete);
-
 	/* Wait for the device to send the TX complete interrupt. */
 	ret = wait_for_completion_interruptible_timeout(
 						&devrec->tx_complete,
-- 
1.7.11.2

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