net: ethtool: add get_rx_ring_count callback to optimize RX ring queries

Add a new optional get_rx_ring_count callback in ethtool_ops to allow
drivers to provide the number of RX rings directly without going through
the full get_rxnfc flow classification interface.

Create ethtool_get_rx_ring_count() to use .get_rx_ring_count if
available, falling back to get_rxnfc() otherwise. It needs to be
non-static, given it will be called by other ethtool functions laters,
as those calling get_rxfh().

Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20250917-gxrings-v4-4-dae520e2e1cb@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index d7d757e72554e113be2fe981b80af4a62ba628dc..c869b7f8bce8b9ecf9f662d95659234dc68ba7e5 100644 (file)
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -968,6 +968,7 @@ struct kernel_ethtool_ts_info {
  * @reset: Reset (part of) the device, as specified by a bitmask of
  *     flags from &enum ethtool_reset_flags.  Returns a negative
  *     error code or zero.
+ * @get_rx_ring_count: Return the number of RX rings
  * @get_rxfh_key_size: Get the size of the RX flow hash key.
  *     Returns zero if not supported for this specific device.
  * @get_rxfh_indir_size: Get the size of the RX flow hash indirection table.
@@ -1162,6 +1163,7 @@ struct ethtool_ops {
        int     (*set_rxnfc)(struct net_device *, struct ethtool_rxnfc *);
        int     (*flash_device)(struct net_device *, struct ethtool_flash *);
        int     (*reset)(struct net_device *, u32 *);
+       u32     (*get_rx_ring_count)(struct net_device *dev);
        u32     (*get_rxfh_key_size)(struct net_device *);
        u32     (*get_rxfh_indir_size)(struct net_device *);
        int     (*get_rxfh)(struct net_device *, struct ethtool_rxfh_param *);

diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 4f58648a27ad6317360fec4fd68593a00910c249..10460ea3717cadca9ecd1b2b8792b15375287e1d 100644 (file)
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -577,6 +577,26 @@ int __ethtool_get_link(struct net_device *dev)
        return netif_running(dev) && dev->ethtool_ops->get_link(dev);
 }
 
+int ethtool_get_rx_ring_count(struct net_device *dev)
+{
+       const struct ethtool_ops *ops = dev->ethtool_ops;
+       struct ethtool_rxnfc rx_rings = {};
+       int ret;
+
+       if (ops->get_rx_ring_count)
+               return ops->get_rx_ring_count(dev);
+
+       if (!ops->get_rxnfc)
+               return -EOPNOTSUPP;
+
+       rx_rings.cmd = ETHTOOL_GRXRINGS;
+       ret = ops->get_rxnfc(dev, &rx_rings, NULL);
+       if (ret < 0)
+               return ret;
+
+       return rx_rings.data;
+}
+
 static int ethtool_get_rxnfc_rule_count(struct net_device *dev)
 {
        const struct ethtool_ops *ops = dev->ethtool_ops;

diff --git a/net/ethtool/common.h b/net/ethtool/common.h
index c4d084dde5bf4f0f9318af8a98815fb9d3c3a246..1609cf4e53ebbd74026cba4fc35dcb1e467e0ed9 100644 (file)
--- a/net/ethtool/common.h
+++ b/net/ethtool/common.h
@@ -54,6 +54,8 @@ void ethtool_ringparam_get_cfg(struct net_device *dev,
                               struct kernel_ethtool_ringparam *kparam,
                               struct netlink_ext_ack *extack);
 
+int ethtool_get_rx_ring_count(struct net_device *dev);
+
 int __ethtool_get_ts_info(struct net_device *dev, struct kernel_ethtool_ts_info *info);
 int ethtool_get_ts_info_by_phc(struct net_device *dev,
                               struct kernel_ethtool_ts_info *info,

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index a0f3de76cea03391fc2126a82bde04ec37524e43..8493ee200601e0979f61c4983ce34e1a82cedc56 100644 (file)
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1212,23 +1212,21 @@ static noinline_for_stack int ethtool_get_rxrings(struct net_device *dev,
                                                  u32 cmd,
                                                  void __user *useraddr)
 {
-       const struct ethtool_ops *ops = dev->ethtool_ops;
        struct ethtool_rxnfc info;
        size_t info_size;
        int ret;
 
-       if (!ops->get_rxnfc)
-               return -EOPNOTSUPP;
-
        info_size = sizeof(info);
        ret = ethtool_rxnfc_copy_struct(cmd, &info, &info_size, useraddr);
        if (ret)
                return ret;
 
-       ret = ops->get_rxnfc(dev, &info, NULL);
+       ret = ethtool_get_rx_ring_count(dev);
        if (ret < 0)
                return ret;
 
+       info.data = ret;
+
        return ethtool_rxnfc_copy_to_user(useraddr, &info, info_size, NULL);
 }