From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
To: bh74.an@samsung.com, ks.giri@samsung.com,
vipul.pandya@samsung.com, peppe.cavallaro@st.com,
alexandre.torgue@st.com
Cc: pavel@ucw.cz, davem@davemloft.net, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, Lino Sanfilippo <LinoSanfilippo@gmx.de>
Subject: [PATCH 1/2] net: ethernet: sxgbe: remove private tx queue lock
Date: Wed, 7 Dec 2016 21:05:37 +0100 [thread overview]
Message-ID: <1481141138-19466-2-git-send-email-LinoSanfilippo@gmx.de> (raw)
In-Reply-To: <1481141138-19466-1-git-send-email-LinoSanfilippo@gmx.de>
The driver uses a private lock for synchronization between the xmit
function and the xmit completion handler, but since the NETIF_F_LLTX flag
is not set, the xmit function is also called with the xmit_lock held.
On the other hand the xmit completion handler first takes the private lock
and (in case that the tx queue has been stopped) the xmit_lock, leading
to a reverse locking order and the potential danger of a deadlock.
Fix this by removing the private lock completely and synchronizing the xmit
function and completion handler solely by means of the xmit_lock. By doing
this also remove the now unnecessary double check for a stopped tx queue.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
---
drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h | 1 -
drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c | 27 +++++------------------
2 files changed, 6 insertions(+), 22 deletions(-)
diff --git a/drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h b/drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h
index 5cb51b6..c61f260 100644
--- a/drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h
+++ b/drivers/net/ethernet/samsung/sxgbe/sxgbe_common.h
@@ -384,7 +384,6 @@ struct sxgbe_tx_queue {
dma_addr_t *tx_skbuff_dma;
struct sk_buff **tx_skbuff;
struct timer_list txtimer;
- spinlock_t tx_lock; /* lock for tx queues */
unsigned int cur_tx;
unsigned int dirty_tx;
u32 tx_count_frames;
diff --git a/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c b/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
index ea44a24..22d3b0b 100644
--- a/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
+++ b/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
@@ -426,9 +426,6 @@ static int init_tx_ring(struct device *dev, u8 queue_no,
tx_ring->dirty_tx = 0;
tx_ring->cur_tx = 0;
- /* initialise TX queue lock */
- spin_lock_init(&tx_ring->tx_lock);
-
return 0;
dmamem_err:
@@ -743,7 +740,7 @@ static void sxgbe_tx_queue_clean(struct sxgbe_tx_queue *tqueue)
dev_txq = netdev_get_tx_queue(priv->dev, queue_no);
- spin_lock(&tqueue->tx_lock);
+ __netif_tx_lock(dev_txq, smp_processor_id());
priv->xstats.tx_clean++;
while (tqueue->dirty_tx != tqueue->cur_tx) {
@@ -781,18 +778,13 @@ static void sxgbe_tx_queue_clean(struct sxgbe_tx_queue *tqueue)
/* wake up queue */
if (unlikely(netif_tx_queue_stopped(dev_txq) &&
- sxgbe_tx_avail(tqueue, tx_rsize) > SXGBE_TX_THRESH(priv))) {
- netif_tx_lock(priv->dev);
- if (netif_tx_queue_stopped(dev_txq) &&
- sxgbe_tx_avail(tqueue, tx_rsize) > SXGBE_TX_THRESH(priv)) {
- if (netif_msg_tx_done(priv))
- pr_debug("%s: restart transmit\n", __func__);
- netif_tx_wake_queue(dev_txq);
- }
- netif_tx_unlock(priv->dev);
+ sxgbe_tx_avail(tqueue, tx_rsize) > SXGBE_TX_THRESH(priv))) {
+ if (netif_msg_tx_done(priv))
+ pr_debug("%s: restart transmit\n", __func__);
+ netif_tx_wake_queue(dev_txq);
}
- spin_unlock(&tqueue->tx_lock);
+ __netif_tx_unlock(dev_txq);
}
/**
@@ -1304,9 +1296,6 @@ static netdev_tx_t sxgbe_xmit(struct sk_buff *skb, struct net_device *dev)
tqueue->hwts_tx_en)))
ctxt_desc_req = 1;
- /* get the spinlock */
- spin_lock(&tqueue->tx_lock);
-
if (priv->tx_path_in_lpi_mode)
sxgbe_disable_eee_mode(priv);
@@ -1316,8 +1305,6 @@ static netdev_tx_t sxgbe_xmit(struct sk_buff *skb, struct net_device *dev)
netdev_err(dev, "%s: Tx Ring is full when %d queue is awake\n",
__func__, txq_index);
}
- /* release the spin lock in case of BUSY */
- spin_unlock(&tqueue->tx_lock);
return NETDEV_TX_BUSY;
}
@@ -1436,8 +1423,6 @@ static netdev_tx_t sxgbe_xmit(struct sk_buff *skb, struct net_device *dev)
priv->hw->dma->enable_dma_transmission(priv->ioaddr, txq_index);
- spin_unlock(&tqueue->tx_lock);
-
return NETDEV_TX_OK;
}
--
1.9.1
next prev parent reply other threads:[~2016-12-07 20:06 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-07 20:05 Remove private locks to avoid possible deadlock Lino Sanfilippo
2016-12-07 20:05 ` Lino Sanfilippo [this message]
2016-12-07 23:15 ` [PATCH 1/2] net: ethernet: sxgbe: remove private tx queue lock Francois Romieu
2016-12-08 20:32 ` Lino Sanfilippo
2016-12-08 21:54 ` Pavel Machek
2016-12-08 22:12 ` Lino Sanfilippo
2016-12-08 22:18 ` Pavel Machek
2016-12-08 22:45 ` Lino Sanfilippo
2016-12-08 23:19 ` Francois Romieu
2016-12-09 11:21 ` Pavel Machek
2016-12-10 2:25 ` Lino Sanfilippo
2016-12-11 20:11 ` Pavel Machek
2016-12-15 19:27 ` Lino Sanfilippo
2016-12-15 21:03 ` Pavel Machek
2016-12-15 21:32 ` Lino Sanfilippo
2016-12-15 22:33 ` Lino Sanfilippo
2016-12-17 17:31 ` Pavel Machek
2016-12-18 0:15 ` Francois Romieu
2016-12-18 16:15 ` Lino Sanfilippo
2016-12-18 17:23 ` Pavel Machek
2016-12-18 18:30 ` Pavel Machek
2016-12-19 22:49 ` Lino Sanfilippo
2016-12-18 20:16 ` Pavel Machek
2016-12-19 10:02 ` Pavel Machek
2016-12-20 0:05 ` Francois Romieu
2016-12-07 20:05 ` [PATCH 2/2] net: ethernet: stmmac: " Lino Sanfilippo
2016-12-07 20:55 ` Pavel Machek
2016-12-07 20:59 ` Pavel Machek
2016-12-07 21:37 ` Pavel Machek
2016-12-07 21:43 ` Lino Sanfilippo
2016-12-07 22:34 ` Lino Sanfilippo
2016-12-07 23:21 ` Pavel Machek
2016-12-07 23:41 ` David Miller
2016-12-08 14:08 ` Pavel Machek
2016-12-08 15:26 ` David Miller
2016-12-08 15:46 ` Pavel Machek
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