net: ethtool: add a mutex protecting RSS contexts

While this is not needed to serialise the ethtool entry points (which
 are all under RTNL), drivers may have cause to asynchronously access
 dev->ethtool->rss_ctx; taking dev->ethtool->rss_lock allows them to
 do this safely without needing to take the RTNL.

Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://patch.msgid.link/7f9c15eb7525bf87af62c275dde3a8570ee8bf0a.1719502240.git.ecree.xilinx@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 9cdbc8e3ed5c7d966ef63fa96be63cef261e78fd..f74bb0cf8ed1ee3635956dfc72d74aa901515790 100644 (file)
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -1104,10 +1104,13 @@ int ethtool_virtdev_set_link_ksettings(struct net_device *dev,
 /**
  * struct ethtool_netdev_state - per-netdevice state for ethtool features
  * @rss_ctx:           XArray of custom RSS contexts
+ * @rss_lock:          Protects entries in @rss_ctx.  May be taken from
+ *                     within RTNL.
  * @wol_enabled:       Wake-on-LAN is enabled
  */
 struct ethtool_netdev_state {
        struct xarray           rss_ctx;
+       struct mutex            rss_lock;
        unsigned                wol_enabled:1;
 };
 

diff --git a/net/core/dev.c b/net/core/dev.c
index 2daed4464c0847f016718e8c08f87a32dd494502..385c4091aa7751697aee795b365246c6906dd25e 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10338,6 +10338,7 @@ int register_netdevice(struct net_device *dev)
 
        /* rss ctx ID 0 is reserved for the default context, start from 1 */
        xa_init_flags(&dev->ethtool->rss_ctx, XA_FLAGS_ALLOC1);
+       mutex_init(&dev->ethtool->rss_lock);
 
        spin_lock_init(&dev->addr_list_lock);
        netdev_set_addr_lockdep_class(dev);
@@ -11243,6 +11244,7 @@ static void netdev_rss_contexts_free(struct net_device *dev)
        struct ethtool_rxfh_context *ctx;
        unsigned long context;
 
+       mutex_lock(&dev->ethtool->rss_lock);
        xa_for_each(&dev->ethtool->rss_ctx, context, ctx) {
                struct ethtool_rxfh_param rxfh;
 
@@ -11262,6 +11264,7 @@ static void netdev_rss_contexts_free(struct net_device *dev)
                kfree(ctx);
        }
        xa_destroy(&dev->ethtool->rss_ctx);
+       mutex_unlock(&dev->ethtool->rss_lock);
 }
 
 /**
@@ -11374,6 +11377,8 @@ void unregister_netdevice_many_notify(struct list_head *head,
                if (dev->netdev_ops->ndo_uninit)
                        dev->netdev_ops->ndo_uninit(dev);
 
+               mutex_destroy(&dev->ethtool->rss_lock);
+
                if (skb)
                        rtmsg_ifinfo_send(skb, dev, GFP_KERNEL, portid, nlh);
 

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 82c610e9e6b2697531871cf72ac5dc7e8aa32701..939ccd106fe1ca528948a1f1489b6c20a4bbf5d6 100644 (file)
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1285,6 +1285,7 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
        struct netlink_ext_ack *extack = NULL;
        struct ethtool_rxnfc rx_rings;
        struct ethtool_rxfh rxfh;
+       bool locked = false; /* dev->ethtool->rss_lock taken */
        u32 indir_bytes = 0;
        bool create = false;
        u8 *rss_config;
@@ -1380,6 +1381,10 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
                }
        }
 
+       if (rxfh.rss_context) {
+               mutex_lock(&dev->ethtool->rss_lock);
+               locked = true;
+       }
        if (create) {
                if (rxfh_dev.rss_delete) {
                        ret = -EINVAL;
@@ -1495,6 +1500,8 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
        }
 
 out:
+       if (locked)
+               mutex_unlock(&dev->ethtool->rss_lock);
        kfree(rss_config);
        return ret;
 }