[PATCH 3.16 239/366] sh_eth: fix invalid context bug while changing link options by ethtool

Ben Hutchings
2018-11-11T19:49:05Z

From: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>

commit 5cb3f52a11e18628fc4bee76dd14b1f0b76349de upstream.

The change fixes sleep in atomic context bug, which is encountered
every time when link settings are changed by ethtool.

Since commit 35b5f6b1a82b ("PHYLIB: Locking fixes for PHY I/O
potentially sleeping") phy_start_aneg() function utilizes a mutex
to serialize changes to phy state, however that helper function is
called in atomic context under a grabbed spinlock, because
phy_start_aneg() is called by phy_ethtool_ksettings_set() and by
replaced phy_ethtool_sset() helpers from phylib.

Now duplex mode setting is enforced in sh_eth_adjust_link() only,
also now RX/TX is disabled when link is put down or modifications
to E-MAC registers ECMR and GECMR are expected for both cases of
checked and ignored link status pin state from E-MAC interrupt handler.

For reference the change is a partial rework of commit 1e1b812bbe10
("sh_eth: fix handling of no LINK signal").

Fixes: dc19e4e5e02f ("sh: sh_eth: Add support ethtool")
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16:
- Keep using phy_ethtool_sset()
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1727,8 +1727,15 @@ static void sh_eth_adjust_link(struct ne
{
struct sh_eth_private *mdp = netdev_priv(ndev);
struct phy_device *phydev = mdp->phydev;
+ unsigned long flags;
int new_state = 0;

+ spin_lock_irqsave(&mdp->lock, flags);
+
+ /* Disable TX and RX right over here, if E-MAC change is ignored */
+ if (mdp->cd->no_psr || mdp->no_ether_link)
+ sh_eth_rcv_snd_disable(ndev);
+
if (phydev->link) {
if (phydev->duplex != mdp->duplex) {
new_state = 1;
@@ -1749,18 +1756,21 @@ static void sh_eth_adjust_link(struct ne
ECMR);
new_state = 1;
mdp->link = phydev->link;
- if (mdp->cd->no_psr || mdp->no_ether_link)
- sh_eth_rcv_snd_enable(ndev);
}
} else if (mdp->link) {
new_state = 1;
mdp->link = 0;
mdp->speed = 0;
mdp->duplex = -1;
- if (mdp->cd->no_psr || mdp->no_ether_link)
- sh_eth_rcv_snd_disable(ndev);
}

+ /* Enable TX and RX right over here, if E-MAC change is ignored */
+ if ((mdp->cd->no_psr || mdp->no_ether_link) && phydev->link)
+ sh_eth_rcv_snd_enable(ndev);
+
+ mmiowb();
+ spin_unlock_irqrestore(&mdp->lock, flags);
+
if (new_state && netif_msg_link(mdp))
phy_print_status(phydev);
}
@@ -1843,35 +1853,8 @@ static int sh_eth_set_settings(struct ne
struct ethtool_cmd *ecmd)
{
struct sh_eth_private *mdp = netdev_priv(ndev);
- unsigned long flags;
- int ret;
-
- spin_lock_irqsave(&mdp->lock, flags);

- /* disable tx and rx */
- sh_eth_rcv_snd_disable(ndev);
-
- ret = phy_ethtool_sset(mdp->phydev, ecmd);
- if (ret)
- goto error_exit;
-
- if (ecmd->duplex == DUPLEX_FULL)
- mdp->duplex = 1;
- else
- mdp->duplex = 0;
-
- if (mdp->cd->set_duplex)
- mdp->cd->set_duplex(ndev);
-
-error_exit:
- mdelay(1);
-
- /* enable tx and rx */
- sh_eth_rcv_snd_enable(ndev);
-
- spin_unlock_irqrestore(&mdp->lock, flags);
-
- return ret;
+ return phy_ethtool_sset(mdp->phydev, ecmd);
}

static int sh_eth_nway_reset(struct net_device *ndev)