netdev - [PATCH] ravb: fix race updating TCCR

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Message-ID: <6587398.M5V25fvqHl@wasted.cogentembedded.com>
Date:	Fri, 17 Jul 2015 00:28:38 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	netdev@...r.kernel.org
Cc:	linux-sh@...r.kernel.org
Subject: [PATCH] ravb: fix race updating TCCR

The TCCR.TSRQn bit may get clearead after TCCR gets read, so that TCCR write
would get skipped. We don't need to check this bit before setting.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>

---
The patch is against Dave Miller's 'net.git' repo plus the patch I sent on
Tuesday.

 drivers/net/ethernet/renesas/ravb_main.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

Index: net/drivers/net/ethernet/renesas/ravb_main.c
===================================================================
--- net.orig/drivers/net/ethernet/renesas/ravb_main.c
+++ net/drivers/net/ethernet/renesas/ravb_main.c
@@ -1275,7 +1275,6 @@ static netdev_tx_t ravb_start_xmit(struc
 	u32 dma_addr;
 	void *buffer;
 	u32 entry;
-	u32 tccr;
 
 	spin_lock_irqsave(&priv->lock, flags);
 	if (priv->cur_tx[q] - priv->dirty_tx[q] >= priv->num_tx_ring[q]) {
@@ -1324,9 +1323,7 @@ static netdev_tx_t ravb_start_xmit(struc
 	dma_wmb();
 	desc->die_dt = DT_FSINGLE;
 
-	tccr = ravb_read(ndev, TCCR);
-	if (!(tccr & (TCCR_TSRQ0 << q)))
-		ravb_write(ndev, tccr | (TCCR_TSRQ0 << q), TCCR);
+	ravb_write(ndev, ravb_read(ndev, TCCR) | (TCCR_TSRQ0 << q), TCCR);
 
 	priv->cur_tx[q]++;
 	if (priv->cur_tx[q] - priv->dirty_tx[q] >= priv->num_tx_ring[q] &&

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