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Subject[patch v2] net: hip04: Make tx coalesce timer actually work
The code sets the expiry value of the timer to a relative value and
starts it with hrtimer_start_expires. That's fine, but that only works
once. The timer is started in relative mode, so the expiry value gets
overwritten with the absolut expiry time (now + expiry).

So once the timer expired, a new call to hrtimer_start_expires results
in an immidiately expired timer, because the expiry value is
already in the past.

Use the proper mechanisms to (re)start the timer in the intended way.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: dingtianhong <dingtianhong@huawei.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: netdev@vger.kernel.org
---
drivers/net/ethernet/hisilicon/hip04_eth.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)

Index: linux/drivers/net/ethernet/hisilicon/hip04_eth.c
===================================================================
--- linux.orig/drivers/net/ethernet/hisilicon/hip04_eth.c
+++ linux/drivers/net/ethernet/hisilicon/hip04_eth.c
@@ -413,6 +413,15 @@ out:
return count;
}

+static void hip04_start_tx_timer(struct hip04_priv *priv)
+{
+ unsigned long ns = priv->tx_coalesce_usecs * NSEC_PER_USEC / 2;
+
+ /* allow timer to fire after half the time at the earliest */
+ hrtimer_start_range_ns(&priv->tx_coalesce_timer, ns_to_ktime(ns),
+ ns, HRTIMER_MODE_REL);
+}
+
static int hip04_mac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
{
struct hip04_priv *priv = netdev_priv(ndev);
@@ -466,8 +475,7 @@ static int hip04_mac_start_xmit(struct s
}
} else if (!hrtimer_is_queued(&priv->tx_coalesce_timer)) {
/* cleanup not pending yet, start a new timer */
- hrtimer_start_expires(&priv->tx_coalesce_timer,
- HRTIMER_MODE_REL);
+ hip04_start_tx_timer(priv);
}

return NETDEV_TX_OK;
@@ -549,7 +557,7 @@ done:
/* clean up tx descriptors and start a new timer if necessary */
tx_remaining = hip04_tx_reclaim(ndev, false);
if (rx < budget && tx_remaining)
- hrtimer_start_expires(&priv->tx_coalesce_timer, HRTIMER_MODE_REL);
+ hip04_start_tx_timer(priv);

return rx;
}
@@ -809,7 +817,6 @@ static int hip04_mac_probe(struct platfo
struct hip04_priv *priv;
struct resource *res;
unsigned int irq;
- ktime_t txtime;
int ret;

ndev = alloc_etherdev(sizeof(struct hip04_priv));
@@ -846,9 +853,6 @@ static int hip04_mac_probe(struct platfo
*/
priv->tx_coalesce_frames = TX_DESC_NUM * 3 / 4;
priv->tx_coalesce_usecs = 200;
- /* allow timer to fire after half the time at the earliest */
- txtime = ktime_set(0, priv->tx_coalesce_usecs * NSEC_PER_USEC / 2);
- hrtimer_set_expires_range(&priv->tx_coalesce_timer, txtime, txtime);
priv->tx_coalesce_timer.function = tx_done;

priv->map = syscon_node_to_regmap(arg.np);

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