netdev - Re: [PATCH net 2/2] net/bonding: correctly proxy slave neigh param setup ndo function

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Date:	Tue, 03 Apr 2012 15:53:46 -0700
From:	Jay Vosburgh <fubar@...ibm.com>
To:	Or Gerlitz <ogerlitz@...lanox.com>
cc:	davem@...emloft.net, roland@...nel.org, netdev@...r.kernel.org,
	Shlomo Pongratz <shlomop@...lanox.com>
Subject: Re: [PATCH net 2/2] net/bonding: correctly proxy slave neigh param setup ndo function

Or Gerlitz <ogerlitz@...lanox.com> wrote:

>From: Shlomo Pongratz <shlomop@...lanox.com>
>
>The current implemenation was buggy for slaves who use ndo_neigh_setup,
>since the networking stack invokes the bonding device ndo entry (from
>neigh_params_alloc) before any devices are enslaved, and the bonding
>driver can't further delegate the call at that point in time. As a
>result when bonding IPoIB devices, the neigh_cleanup hasn't been called.
>
>Fix that by deferring the actual call into the slave ndo_neigh_setup
>from the time the bonding neigh_setup is called.
>
>Signed-off-by: Shlomo Pongratz <shlomop@...lanox.com>
>---
> drivers/net/bonding/bond_main.c |   51 ++++++++++++++++++++++++++++++++------
> 1 files changed, 43 insertions(+), 8 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>index b0a278d..2eed155 100644
>--- a/drivers/net/bonding/bond_main.c
>+++ b/drivers/net/bonding/bond_main.c
>@@ -3707,17 +3707,52 @@ static void bond_set_multicast_list(struct net_device *bond_dev)
> 	read_unlock(&bond->lock);
> }
>
>-static int bond_neigh_setup(struct net_device *dev, struct neigh_parms *parms)
>+static int bond_neigh_init(struct neighbour *n)
> {
>-	struct bonding *bond = netdev_priv(dev);
>+	struct bonding *bond = netdev_priv(n->dev);
> 	struct slave *slave = bond->first_slave;
>+	const struct net_device_ops *slave_ops;
>+	struct neigh_parms parms;
>+	int ret;
>+
>+	if (!slave)
>+		return 0;
>+
>+	slave_ops = slave->dev->netdev_ops;
>+
>+	if (!slave_ops->ndo_neigh_setup)
>+		return 0;
>+
>+	parms.neigh_setup = NULL;
>+	parms.neigh_cleanup = NULL;
>+	ret = slave_ops->ndo_neigh_setup(slave->dev, &parms);
>+	if (ret)
>+		return ret;
>+
>+	/*
>+	 * must bind here to the slave clenaup. Since when last slave is removed
>+	 * there will be no slave device to dereference in a bonding
>+	 * neigh_cleanup function that we have could add.
>+	 */
>+	n->parms->neigh_cleanup = parms.neigh_cleanup;

	I'd write this comment as:

	/* Assign slave's neigh_cleanup to neighbour in case cleanup is
	 * called after bond has been destroyed.  Assumes that all slaves
	 * utilize the same neigh_cleanup (true at this writing as only user
	 * is ipoib).
	 */

	I.e., this logic works only because there cannot currently be a
situation wherein two slaves have different neigh_cleanup functions
(including one slave with a neigh_cleanup, and another without).

>+	/* Does slave implement neigh_setup ? */
>+	if (!parms.neigh_setup)
>+		return 0;

	I don't think this comment is necessary.

	-J

>+
>+	return parms.neigh_setup(n);
>+}
>+
>+/*
>+ * The bonding ndo_neigh_setup is called at init time beofre any
>+ * slave exists. So we must declare proxy setup function which will
>+ * be used at run time to resolve the actual slave neigh param setup.
>+ */
>+static int bond_neigh_setup(struct net_device *dev,
>+			    struct neigh_parms *parms)
>+{
>+	parms->neigh_setup   = bond_neigh_init;
>
>-	if (slave) {
>-		const struct net_device_ops *slave_ops
>-			= slave->dev->netdev_ops;
>-		if (slave_ops->ndo_neigh_setup)
>-			return slave_ops->ndo_neigh_setup(slave->dev, parms);
>-	}
> 	return 0;
> }

---
	-Jay Vosburgh, IBM Linux Technology Center, fubar@...ibm.com

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