target/linux/armsr/patches-6.1/701-v6.2-0012-net-dpaa2-mac-move-rtnl_lock-only-around-phylink.patch

   1 From 4ea2faf5bb13d9ba9f07e996d495c4cbe34a4236 Mon Sep 17 00:00:00 2001
   2 From: Vladimir Oltean <vladimir.oltean@nxp.com>
   3 Date: Tue, 29 Nov 2022 16:12:21 +0200
   4 Subject: [PATCH 14/14] net: dpaa2-mac: move rtnl_lock() only around
   5  phylink_{,dis}connect_phy()
   6
   7 After the introduction of a private mac_lock that serializes access to
   8 priv->mac (and port_priv->mac in the switch), the only remaining purpose
   9 of rtnl_lock() is to satisfy the locking requirements of
  10 phylink_fwnode_phy_connect() and phylink_disconnect_phy().
  11
  12 But the functions these live in, dpaa2_mac_connect() and
  13 dpaa2_mac_disconnect(), have contradictory locking requirements.
  14 While phylink_fwnode_phy_connect() wants rtnl_lock() to be held,
  15 phylink_create() wants it to not be held.
  16
  17 Move the rtnl_lock() from top-level (in the dpaa2-eth and dpaa2-switch
  18 drivers) to only surround the phylink calls that require it, in the
  19 dpaa2-mac library code.
  20
  21 This is possible because dpaa2_mac_connect() and dpaa2_mac_disconnect()
  22 run unlocked, and there isn't any danger of an AB/BA deadlock between
  23 the rtnl_mutex and other private locks.
  24
  25 Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
  26 Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com>
  27 Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com>
  28 Signed-off-by: Paolo Abeni <pabeni@redhat.com>
  29 ---
  30  drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c    | 4 ----
  31  drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c    | 5 +++++
  32  drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c | 4 ----
  33  3 files changed, 5 insertions(+), 8 deletions(-)
  34
  35 --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
  36 +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
  37 @@ -4527,7 +4527,6 @@ static irqreturn_t dpni_irq0_handler_thr
  38                 dpaa2_eth_set_mac_addr(netdev_priv(net_dev));
  39                 dpaa2_eth_update_tx_fqids(priv);
  40
  41 -               rtnl_lock();
  42                 /* We can avoid locking because the "endpoint changed" IRQ
  43                  * handler is the only one who changes priv->mac at runtime,
  44                  * so we are not racing with anyone.
  45 @@ -4537,7 +4536,6 @@ static irqreturn_t dpni_irq0_handler_thr
  46                         dpaa2_eth_disconnect_mac(priv);
  47                 else
  48                         dpaa2_eth_connect_mac(priv);
  49 -               rtnl_unlock();
  50         }
  51
  52         return IRQ_HANDLED;
  53 @@ -4856,9 +4854,7 @@ static int dpaa2_eth_remove(struct fsl_m
  54         else
  55                 fsl_mc_free_irqs(ls_dev);
  56
  57 -       rtnl_lock();
  58         dpaa2_eth_disconnect_mac(priv);
  59 -       rtnl_unlock();
  60         dpaa2_eth_free_rings(priv);
  61         free_percpu(priv->fd);
  62         free_percpu(priv->sgt_cache);
  63 --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
  64 +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
  65 @@ -428,7 +428,9 @@ int dpaa2_mac_connect(struct dpaa2_mac *
  66         }
  67         mac->phylink = phylink;
  68
  69 +       rtnl_lock();
  70         err = phylink_fwnode_phy_connect(mac->phylink, dpmac_node, 0);
  71 +       rtnl_unlock();
  72         if (err) {
  73                 netdev_err(net_dev, "phylink_fwnode_phy_connect() = %d\n", err);
  74                 goto err_phylink_destroy;
  75 @@ -446,7 +448,10 @@ err_pcs_destroy:
  76
  77  void dpaa2_mac_disconnect(struct dpaa2_mac *mac)
  78  {
  79 +       rtnl_lock();
  80         phylink_disconnect_phy(mac->phylink);
  81 +       rtnl_unlock();
  82 +
  83         phylink_destroy(mac->phylink);
  84         dpaa2_pcs_destroy(mac);
  85         of_phy_put(mac->serdes_phy);
  86 --- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
  87 +++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c
  88 @@ -1530,7 +1530,6 @@ static irqreturn_t dpaa2_switch_irq0_han
  89         }
  90
  91         if (status & DPSW_IRQ_EVENT_ENDPOINT_CHANGED) {
  92 -               rtnl_lock();
  93                 /* We can avoid locking because the "endpoint changed" IRQ
  94                  * handler is the only one who changes priv->mac at runtime,
  95                  * so we are not racing with anyone.
  96 @@ -1540,7 +1539,6 @@ static irqreturn_t dpaa2_switch_irq0_han
  97                         dpaa2_switch_port_disconnect_mac(port_priv);
  98                 else
  99                         dpaa2_switch_port_connect_mac(port_priv);
 100 -               rtnl_unlock();
 101         }
 102
 103  out:
 104 @@ -2958,9 +2956,7 @@ static void dpaa2_switch_remove_port(str
 105  {
 106         struct ethsw_port_priv *port_priv = ethsw->ports[port_idx];
 107
 108 -       rtnl_lock();
 109         dpaa2_switch_port_disconnect_mac(port_priv);
 110 -       rtnl_unlock();
 111         free_netdev(port_priv->netdev);
 112         ethsw->ports[port_idx] = NULL;
 113  }