diff mbox series

[v2,net-next,03/11] net: bridge: don't print in br_switchdev_set_port_flag

Message ID 20210209151936.97382-4-olteanv@gmail.com (mailing list archive)
State New, archived
Headers show
Series Cleanup in brport flags switchdev offload for DSA | expand

Commit Message

Vladimir Oltean Feb. 9, 2021, 3:19 p.m. UTC 
From: Vladimir Oltean <vladimir.oltean@nxp.com>

Currently br_switchdev_set_port_flag has two options for error handling
and neither is good:
- The driver returns -EOPNOTSUPP in PRE_BRIDGE_FLAGS if it doesn't
  support offloading that flag, and this gets silently ignored and
  converted to an errno of 0. Nobody does this.
- The driver returns some other error code, like -EINVAL, in
  PRE_BRIDGE_FLAGS, and br_switchdev_set_port_flag shouts loudly.

The problem is that we'd like to offload some port flags during bridge
join and leave, but also not have the bridge shout at us if those fail.
But on the other hand we'd like the user to know that we can't offload
something when they set that through netlink. And since we can't have
the driver return -EOPNOTSUPP or -EINVAL depending on whether it's
called by the user or internally by the bridge, let's just add an extack
argument to br_switchdev_set_port_flag and propagate it to its callers.
Then, when we need offloading to really fail silently, this can simply
be passed a NULL argument.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
Changes in v2:
- br_set_port_flag now returns void, so no extack there.
- don't overwrite extack in br_switchdev_set_port_flag if already
  populated.

 net/bridge/br_netlink.c   |  9 +++++----
 net/bridge/br_private.h   |  6 ++++--
 net/bridge/br_switchdev.c | 13 +++++++------
 3 files changed, 16 insertions(+), 12 deletions(-)

Comments

Vladimir Oltean Feb. 9, 2021, 5:36 p.m. UTC | #1 
On Tue, Feb 09, 2021 at 05:19:28PM +0200, Vladimir Oltean wrote:
> From: Vladimir Oltean <vladimir.oltean@nxp.com>
>
> Currently br_switchdev_set_port_flag has two options for error handling
> and neither is good:
> - The driver returns -EOPNOTSUPP in PRE_BRIDGE_FLAGS if it doesn't
>   support offloading that flag, and this gets silently ignored and
>   converted to an errno of 0. Nobody does this.
> - The driver returns some other error code, like -EINVAL, in
>   PRE_BRIDGE_FLAGS, and br_switchdev_set_port_flag shouts loudly.
>
> The problem is that we'd like to offload some port flags during bridge
> join and leave, but also not have the bridge shout at us if those fail.
> But on the other hand we'd like the user to know that we can't offload
> something when they set that through netlink. And since we can't have
> the driver return -EOPNOTSUPP or -EINVAL depending on whether it's
> called by the user or internally by the bridge, let's just add an extack
> argument to br_switchdev_set_port_flag and propagate it to its callers.
> Then, when we need offloading to really fail silently, this can simply
> be passed a NULL argument.
>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---

The build fails because since I started working on v2 and until I sent
it, Jakub merged net into net-next which contained this fix:
https://patchwork.kernel.org/project/netdevbpf/patch/20210207194733.1811529-1-olteanv@gmail.com/
for which I couldn't change prototype due to it missing in net-next.
I think I would like to rather wait to gather some feedback first before
respinning v3, if possible.
Ido Schimmel Feb. 9, 2021, 6:26 p.m. UTC | #2 
On Tue, Feb 09, 2021 at 07:36:31PM +0200, Vladimir Oltean wrote:
> On Tue, Feb 09, 2021 at 05:19:28PM +0200, Vladimir Oltean wrote:
> > From: Vladimir Oltean <vladimir.oltean@nxp.com>
> >
> > Currently br_switchdev_set_port_flag has two options for error handling
> > and neither is good:
> > - The driver returns -EOPNOTSUPP in PRE_BRIDGE_FLAGS if it doesn't
> >   support offloading that flag, and this gets silently ignored and
> >   converted to an errno of 0. Nobody does this.
> > - The driver returns some other error code, like -EINVAL, in
> >   PRE_BRIDGE_FLAGS, and br_switchdev_set_port_flag shouts loudly.
> >
> > The problem is that we'd like to offload some port flags during bridge
> > join and leave, but also not have the bridge shout at us if those fail.
> > But on the other hand we'd like the user to know that we can't offload
> > something when they set that through netlink. And since we can't have
> > the driver return -EOPNOTSUPP or -EINVAL depending on whether it's
> > called by the user or internally by the bridge, let's just add an extack
> > argument to br_switchdev_set_port_flag and propagate it to its callers.
> > Then, when we need offloading to really fail silently, this can simply
> > be passed a NULL argument.
> >
> > Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> > ---
> 
> The build fails because since I started working on v2 and until I sent
> it, Jakub merged net into net-next which contained this fix:
> https://patchwork.kernel.org/project/netdevbpf/patch/20210207194733.1811529-1-olteanv@gmail.com/
> for which I couldn't change prototype due to it missing in net-next.
> I think I would like to rather wait to gather some feedback first before
> respinning v3, if possible.

It seems that in the sysfs call path br_switchdev_set_port_flag() will
be called with the bridge lock held, which is going to be a problem
given that patch #8 allows this function to block.
diff mbox series

Patch

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 2c110bcbc6d0..3ba23fb95370 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -866,7 +866,8 @@  static void br_set_port_flag(struct net_bridge_port *p, struct nlattr *tb[],
 }
 
 /* Process bridge protocol info on port */
-static int br_setport(struct net_bridge_port *p, struct nlattr *tb[])
+static int br_setport(struct net_bridge_port *p, struct nlattr *tb[],
+		      struct netlink_ext_ack *extack)
 {
 	unsigned long old_flags, changed_mask;
 	bool br_vlan_tunnel_old;
@@ -898,7 +899,7 @@  static int br_setport(struct net_bridge_port *p, struct nlattr *tb[])
 
 	spin_unlock_bh(&p->br->lock);
 
-	err = br_switchdev_set_port_flag(p, p->flags, changed_mask);
+	err = br_switchdev_set_port_flag(p, p->flags, changed_mask, extack);
 	if (err) {
 		spin_lock_bh(&p->br->lock);
 		p->flags = old_flags;
@@ -1021,7 +1022,7 @@  int br_setlink(struct net_device *dev, struct nlmsghdr *nlh, u16 flags,
 			if (err)
 				return err;
 
-			err = br_setport(p, tb);
+			err = br_setport(p, tb, extack);
 		} else {
 			/* Binary compatibility with old RSTP */
 			if (nla_len(protinfo) < sizeof(u8))
@@ -1111,7 +1112,7 @@  static int br_port_slave_changelink(struct net_device *brdev,
 	if (!data)
 		return 0;
 
-	return br_setport(br_port_get_rtnl(dev), data);
+	return br_setport(br_port_get_rtnl(dev), data, extack);
 }
 
 static int br_port_fill_slave_info(struct sk_buff *skb,
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index d242ba668e47..a1639d41188b 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -1575,7 +1575,8 @@  bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
 				  const struct sk_buff *skb);
 int br_switchdev_set_port_flag(struct net_bridge_port *p,
 			       unsigned long flags,
-			       unsigned long mask);
+			       unsigned long mask,
+			       struct netlink_ext_ack *extack);
 void br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb,
 			     int type);
 int br_switchdev_port_vlan_add(struct net_device *dev, u16 vid, u16 flags,
@@ -1605,7 +1606,8 @@  static inline bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
 
 static inline int br_switchdev_set_port_flag(struct net_bridge_port *p,
 					     unsigned long flags,
-					     unsigned long mask)
+					     unsigned long mask,
+					     struct netlink_ext_ack *extack)
 {
 	return 0;
 }
diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
index c004ade25ac0..ac8dead86bf2 100644
--- a/net/bridge/br_switchdev.c
+++ b/net/bridge/br_switchdev.c
@@ -60,7 +60,8 @@  bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
 
 int br_switchdev_set_port_flag(struct net_bridge_port *p,
 			       unsigned long flags,
-			       unsigned long mask)
+			       unsigned long mask,
+			       struct netlink_ext_ack *extack)
 {
 	struct switchdev_attr attr = {
 		.orig_dev = p->dev,
@@ -80,14 +81,15 @@  int br_switchdev_set_port_flag(struct net_bridge_port *p,
 
 	/* We run from atomic context here */
 	err = call_switchdev_notifiers(SWITCHDEV_PORT_ATTR_SET, p->dev,
-				       &info.info, NULL);
+				       &info.info, extack);
 	err = notifier_to_errno(err);
 	if (err == -EOPNOTSUPP)
 		return 0;
 
 	if (err) {
-		br_warn(p->br, "bridge flag offload is not supported %u(%s)\n",
-			(unsigned int)p->port_no, p->dev->name);
+		if (extack && !extack->_msg)
+			NL_SET_ERR_MSG_MOD(extack,
+					   "bridge flag offload is not supported");
 		return -EOPNOTSUPP;
 	}
 
@@ -97,8 +99,7 @@  int br_switchdev_set_port_flag(struct net_bridge_port *p,
 
 	err = switchdev_port_attr_set(p->dev, &attr);
 	if (err) {
-		br_warn(p->br, "error setting offload flag on port %u(%s)\n",
-			(unsigned int)p->port_no, p->dev->name);
+		NL_SET_ERR_MSG_MOD(extack, "error setting offload flag on port");
 		return err;
 	}