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Subject[PATCH] Add Multiple TX/RX Queues Support for WWAN Network Device
Date
From: Xiayu Zhang <Xiayu.Zhang@mediatek.com>

This patch adds 2 callback functions get_num_tx_queues() and
get_num_rx_queues() to let WWAN network device driver customize its own
TX and RX queue numbers. It gives WWAN driver a chance to implement its
own software strategies, such as TX Qos.

Currently, if WWAN device driver creates default bearer interface when
calling wwan_register_ops(), there will be only 1 TX queue and 1 RX queue
for the WWAN network device. In this case, driver is not able to enlarge
the queue numbers by calling netif_set_real_num_tx_queues() or
netif_set_real_num_rx_queues() to take advantage of the network device's
capability of supporting multiple TX/RX queues.

As for additional interfaces of secondary bearers, if userspace service
doesn't specify the num_tx_queues or num_rx_queues in netlink message or
iproute2 command, there also will be only 1 TX queue and 1 RX queue for
each additional interface. If userspace service specifies the num_tx_queues
and num_rx_queues, however, these numbers could be not able to match the
capabilities of network device.

Besides, userspace service is hard to learn every WWAN network device's
TX/RX queue numbers.

In order to let WWAN driver determine the queue numbers, this patch adds
below callback functions in wwan_ops:
struct wwan_ops {
unsigned int priv_size;
...
unsigned int (*get_num_tx_queues)(unsigned int hint_num);
unsigned int (*get_num_rx_queues)(unsigned int hint_num);
};

WWAN subsystem uses the input parameters num_tx_queues and num_rx_queues of
wwan_rtnl_alloc() as hint values, and passes the 2 values to the two
callback functions. WWAN device driver should determine the actual numbers
of network device's TX and RX queues according to the hint value and
device's capabilities.

Signed-off-by: Xiayu Zhang <Xiayu.Zhang@mediatek.com>
---
drivers/net/wwan/wwan_core.c | 25 ++++++++++++++++++++++++-
include/linux/wwan.h | 6 ++++++
2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index d293ab688044..00095c6987be 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -823,6 +823,7 @@ static struct net_device *wwan_rtnl_alloc(struct nlattr *tb[],
struct wwan_device *wwandev = wwan_dev_get_by_name(devname);
struct net_device *dev;
unsigned int priv_size;
+ unsigned int num_txqs, num_rxqs;

if (IS_ERR(wwandev))
return ERR_CAST(wwandev);
@@ -833,9 +834,31 @@ static struct net_device *wwan_rtnl_alloc(struct nlattr *tb[],
goto out;
}

+ /* let wwan device driver determine TX queue number if it wants */
+ if (wwandev->ops->get_num_tx_queues) {
+ num_txqs = wwandev->ops->get_num_tx_queues(num_tx_queues);
+ if (num_txqs < 1 || num_txqs > 4096) {
+ dev = ERR_PTR(-EINVAL);
+ goto out;
+ }
+ } else {
+ num_txqs = num_tx_queues;
+ }
+
+ /* let wwan device driver determine RX queue number if it wants */
+ if (wwandev->ops->get_num_rx_queues) {
+ num_rxqs = wwandev->ops->get_num_rx_queues(num_rx_queues);
+ if (num_rxqs < 1 || num_rxqs > 4096) {
+ dev = ERR_PTR(-EINVAL);
+ goto out;
+ }
+ } else {
+ num_rxqs = num_rx_queues;
+ }
+
priv_size = sizeof(struct wwan_netdev_priv) + wwandev->ops->priv_size;
dev = alloc_netdev_mqs(priv_size, ifname, name_assign_type,
- wwandev->ops->setup, num_tx_queues, num_rx_queues);
+ wwandev->ops->setup, num_txqs, num_rxqs);

if (dev) {
SET_NETDEV_DEV(dev, &wwandev->dev);
diff --git a/include/linux/wwan.h b/include/linux/wwan.h
index 9fac819f92e3..69c0af7ab6af 100644
--- a/include/linux/wwan.h
+++ b/include/linux/wwan.h
@@ -156,6 +156,10 @@ static inline void *wwan_netdev_drvpriv(struct net_device *dev)
* @setup: set up a new netdev
* @newlink: register the new netdev
* @dellink: remove the given netdev
+ * @get_num_tx_queues: determine number of transmit queues
+ * to create when creating a new device.
+ * @get_num_rx_queues: determine number of receive queues
+ * to create when creating a new device.
*/
struct wwan_ops {
unsigned int priv_size;
@@ -164,6 +168,8 @@ struct wwan_ops {
u32 if_id, struct netlink_ext_ack *extack);
void (*dellink)(void *ctxt, struct net_device *dev,
struct list_head *head);
+ unsigned int (*get_num_tx_queues)(unsigned int hint_num);
+ unsigned int (*get_num_rx_queues)(unsigned int hint_num);
};

int wwan_register_ops(struct device *parent, const struct wwan_ops *ops,
--
2.17.0
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