Discussion:
[PATCH net-next 0/2] bridge: make setlink/dellink notifications more accurate
(too old to reply)
Nikolay Aleksandrov
2017-10-19 15:54:57 UTC
Permalink
Hi,
Before this set the bridge would generate a notification on vlan add or del
even if they didn't actually do any changes, which confuses listeners and
is generally not preferred. We could also lose notifications on actual
changes if one adds a range of vlans and there's an error in the middle.
The problem with just breaking and returning an error is that we could
break existing user-space scripts which rely on the vlan delete to clear
all existing entries in the specified range and ignore the non-existing
errors (typically used to clear the current vlan config).
So in order to make the notifications more accurate while keeping backwards
compatibility we add a boolean that tracks if anything actually changed
during the config calls.

The vlan add is more difficult to fix because it always returns 0 even if
nothing changed, so we use EEXIST to signal that and in order not to break
overlapping vlan range add or script return expectations we clear it on
return, the functions used by vlan add are not expected to return EEXIST.

Thanks,
Nik

Nikolay Aleksandrov (2):
bridge: netlink: make setlink/dellink notifications more accurate
bridge: vlan: return EEXIST on add if nothing changed

net/bridge/br_netlink.c | 49 ++++++++++++++++++++++++++----------------
net/bridge/br_netlink_tunnel.c | 14 +++++++-----
net/bridge/br_private_tunnel.h | 3 ++-
net/bridge/br_vlan.c | 38 +++++++++++++++++++++-----------
4 files changed, 68 insertions(+), 36 deletions(-)
--
2.1.4
Nikolay Aleksandrov
2017-10-19 15:54:58 UTC
Permalink
Before this patch we had cases that either sent notifications when there
were in fact no changes (e.g. non-existent vlan delete) or didn't send
notifications when there were changes (e.g. vlan add range with an error in
the middle, port flags change + vlan update error). This patch sends down
a boolean to the functions setlink/dellink use and if there is even a
single configuration change (port flag, vlan add/del, port state) then
we always send a notification. This is all done to keep backwards
compatibility with the opportunistic vlan delete, where one could
specify a vlan range that has missing vlans inside and still everything
in that range will be cleared, this is mostly used to clear the whole
vlan config with a single call, i.e. range 1-4094.

Signed-off-by: Nikolay Aleksandrov <***@cumulusnetworks.com>
---
net/bridge/br_netlink.c | 44 +++++++++++++++++++++++++-----------------
net/bridge/br_netlink_tunnel.c | 14 +++++++++-----
net/bridge/br_private_tunnel.h | 3 ++-
3 files changed, 37 insertions(+), 24 deletions(-)

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index f0e82682e071..e8d74a3f44f7 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -506,7 +506,7 @@ int br_getlink(struct sk_buff *skb, u32 pid, u32 seq,
}

static int br_vlan_info(struct net_bridge *br, struct net_bridge_port *p,
- int cmd, struct bridge_vlan_info *vinfo)
+ int cmd, struct bridge_vlan_info *vinfo, bool *changed)
{
int err = 0;

@@ -517,21 +517,24 @@ static int br_vlan_info(struct net_bridge *br, struct net_bridge_port *p,
* per-VLAN entry as well
*/
err = nbp_vlan_add(p, vinfo->vid, vinfo->flags);
- if (err)
- break;
} else {
vinfo->flags |= BRIDGE_VLAN_INFO_BRENTRY;
err = br_vlan_add(br, vinfo->vid, vinfo->flags);
}
+ if (!err)
+ *changed = true;
break;

case RTM_DELLINK:
if (p) {
- nbp_vlan_delete(p, vinfo->vid);
- if (vinfo->flags & BRIDGE_VLAN_INFO_MASTER)
- br_vlan_delete(p->br, vinfo->vid);
- } else {
- br_vlan_delete(br, vinfo->vid);
+ if (!nbp_vlan_delete(p, vinfo->vid))
+ *changed = true;
+
+ if ((vinfo->flags & BRIDGE_VLAN_INFO_MASTER) &&
+ !br_vlan_delete(p->br, vinfo->vid))
+ *changed = true;
+ } else if (!br_vlan_delete(br, vinfo->vid)) {
+ *changed = true;
}
break;
}
@@ -542,7 +545,8 @@ static int br_vlan_info(struct net_bridge *br, struct net_bridge_port *p,
static int br_process_vlan_info(struct net_bridge *br,
struct net_bridge_port *p, int cmd,
struct bridge_vlan_info *vinfo_curr,
- struct bridge_vlan_info **vinfo_last)
+ struct bridge_vlan_info **vinfo_last,
+ bool *changed)
{
if (!vinfo_curr->vid || vinfo_curr->vid >= VLAN_VID_MASK)
return -EINVAL;
@@ -572,7 +576,7 @@ static int br_process_vlan_info(struct net_bridge *br,
sizeof(struct bridge_vlan_info));
for (v = (*vinfo_last)->vid; v <= vinfo_curr->vid; v++) {
tmp_vinfo.vid = v;
- err = br_vlan_info(br, p, cmd, &tmp_vinfo);
+ err = br_vlan_info(br, p, cmd, &tmp_vinfo, changed);
if (err)
break;
}
@@ -581,13 +585,13 @@ static int br_process_vlan_info(struct net_bridge *br,
return 0;
}

- return br_vlan_info(br, p, cmd, vinfo_curr);
+ return br_vlan_info(br, p, cmd, vinfo_curr, changed);
}

static int br_afspec(struct net_bridge *br,
struct net_bridge_port *p,
struct nlattr *af_spec,
- int cmd)
+ int cmd, bool *changed)
{
struct bridge_vlan_info *vinfo_curr = NULL;
struct bridge_vlan_info *vinfo_last = NULL;
@@ -607,7 +611,8 @@ static int br_afspec(struct net_bridge *br,
return err;
err = br_process_vlan_tunnel_info(br, p, cmd,
&tinfo_curr,
- &tinfo_last);
+ &tinfo_last,
+ changed);
if (err)
return err;
break;
@@ -616,7 +621,7 @@ static int br_afspec(struct net_bridge *br,
return -EINVAL;
vinfo_curr = nla_data(attr);
err = br_process_vlan_info(br, p, cmd, vinfo_curr,
- &vinfo_last);
+ &vinfo_last, changed);
if (err)
return err;
break;
@@ -804,6 +809,7 @@ int br_setlink(struct net_device *dev, struct nlmsghdr *nlh, u16 flags)
struct nlattr *afspec;
struct net_bridge_port *p;
struct nlattr *tb[IFLA_BRPORT_MAX + 1];
+ bool changed = false;
int err = 0;

protinfo = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_PROTINFO);
@@ -839,14 +845,15 @@ int br_setlink(struct net_device *dev, struct nlmsghdr *nlh, u16 flags)
}
if (err)
goto out;
+ changed = true;
}

if (afspec) {
err = br_afspec((struct net_bridge *)netdev_priv(dev), p,
- afspec, RTM_SETLINK);
+ afspec, RTM_SETLINK, &changed);
}

- if (err == 0)
+ if (changed)
br_ifinfo_notify(RTM_NEWLINK, p);
out:
return err;
@@ -857,6 +864,7 @@ int br_dellink(struct net_device *dev, struct nlmsghdr *nlh, u16 flags)
{
struct nlattr *afspec;
struct net_bridge_port *p;
+ bool changed = false;
int err = 0;

afspec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC);
@@ -869,8 +877,8 @@ int br_dellink(struct net_device *dev, struct nlmsghdr *nlh, u16 flags)
return -EINVAL;

err = br_afspec((struct net_bridge *)netdev_priv(dev), p,
- afspec, RTM_DELLINK);
- if (err == 0)
+ afspec, RTM_DELLINK, &changed);
+ if (changed)
/* Send RTM_NEWLINK because userspace
* expects RTM_NEWLINK for vlan dels
*/
diff --git a/net/bridge/br_netlink_tunnel.c b/net/bridge/br_netlink_tunnel.c
index 3712c7f0e00c..da8cb99fd259 100644
--- a/net/bridge/br_netlink_tunnel.c
+++ b/net/bridge/br_netlink_tunnel.c
@@ -198,7 +198,7 @@ static const struct nla_policy vlan_tunnel_policy[IFLA_BRIDGE_VLAN_TUNNEL_MAX +
};

static int br_vlan_tunnel_info(struct net_bridge_port *p, int cmd,
- u16 vid, u32 tun_id)
+ u16 vid, u32 tun_id, bool *changed)
{
int err = 0;

@@ -208,9 +208,12 @@ static int br_vlan_tunnel_info(struct net_bridge_port *p, int cmd,
switch (cmd) {
case RTM_SETLINK:
err = nbp_vlan_tunnel_info_add(p, vid, tun_id);
+ if (!err)
+ *changed = true;
break;
case RTM_DELLINK:
- nbp_vlan_tunnel_info_delete(p, vid);
+ if (!nbp_vlan_tunnel_info_delete(p, vid))
+ *changed = true;
break;
}

@@ -254,7 +257,8 @@ int br_parse_vlan_tunnel_info(struct nlattr *attr,
int br_process_vlan_tunnel_info(struct net_bridge *br,
struct net_bridge_port *p, int cmd,
struct vtunnel_info *tinfo_curr,
- struct vtunnel_info *tinfo_last)
+ struct vtunnel_info *tinfo_last,
+ bool *changed)
{
int err;

@@ -272,7 +276,7 @@ int br_process_vlan_tunnel_info(struct net_bridge *br,
return -EINVAL;
t = tinfo_last->tunid;
for (v = tinfo_last->vid; v <= tinfo_curr->vid; v++) {
- err = br_vlan_tunnel_info(p, cmd, v, t);
+ err = br_vlan_tunnel_info(p, cmd, v, t, changed);
if (err)
return err;
t++;
@@ -283,7 +287,7 @@ int br_process_vlan_tunnel_info(struct net_bridge *br,
if (tinfo_last->flags)
return -EINVAL;
err = br_vlan_tunnel_info(p, cmd, tinfo_curr->vid,
- tinfo_curr->tunid);
+ tinfo_curr->tunid, changed);
if (err)
return err;
memset(tinfo_last, 0, sizeof(struct vtunnel_info));
diff --git a/net/bridge/br_private_tunnel.h b/net/bridge/br_private_tunnel.h
index 4a447a378ab3..a259471bfd78 100644
--- a/net/bridge/br_private_tunnel.h
+++ b/net/bridge/br_private_tunnel.h
@@ -26,7 +26,8 @@ int br_process_vlan_tunnel_info(struct net_bridge *br,
struct net_bridge_port *p,
int cmd,
struct vtunnel_info *tinfo_curr,
- struct vtunnel_info *tinfo_last);
+ struct vtunnel_info *tinfo_last,
+ bool *changed);
int br_get_vlan_tunnel_info_size(struct net_bridge_vlan_group *vg);
int br_fill_vlan_tunnel_info(struct sk_buff *skb,
struct net_bridge_vlan_group *vg);
--
2.1.4
Nikolay Aleksandrov
2017-10-19 15:54:59 UTC
Permalink
Before this patch there was no way to tell if the vlan add operation
actually changed anything, thus we would always generate a notification
on adds. Let's make the notifications more precise and generate them
only if anything changed, so use EEXIST error to signal that the vlan
was not updated in any way. We just need to be careful about a few
places that could re-add the same vlan with the same flags not to return
any errors on EEXIST.

Signed-off-by: Nikolay Aleksandrov <***@cumulusnetworks.com>
---
net/bridge/br_netlink.c | 5 +++++
net/bridge/br_vlan.c | 38 ++++++++++++++++++++++++++------------
2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index e8d74a3f44f7..80d9334a4b46 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -523,6 +523,11 @@ static int br_vlan_info(struct net_bridge *br, struct net_bridge_port *p,
}
if (!err)
*changed = true;
+ else if (err == -EEXIST)
+ /* nothing changed, return 0 for overlapping range add
+ * and compatibility reasons
+ */
+ err = 0;
break;

case RTM_DELLINK:
diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index 233a30040c91..e021a80eb8e9 100644
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -32,27 +32,34 @@ static struct net_bridge_vlan *br_vlan_lookup(struct rhashtable *tbl, u16 vid)
return rhashtable_lookup_fast(tbl, &vid, br_vlan_rht_params);
}

-static void __vlan_add_pvid(struct net_bridge_vlan_group *vg, u16 vid)
+static bool __vlan_add_pvid(struct net_bridge_vlan_group *vg, u16 vid)
{
if (vg->pvid == vid)
- return;
+ return false;

smp_wmb();
vg->pvid = vid;
+
+ return true;
}

-static void __vlan_delete_pvid(struct net_bridge_vlan_group *vg, u16 vid)
+static bool __vlan_delete_pvid(struct net_bridge_vlan_group *vg, u16 vid)
{
if (vg->pvid != vid)
- return;
+ return false;

smp_wmb();
vg->pvid = 0;
+
+ return true;
}

-static void __vlan_add_flags(struct net_bridge_vlan *v, u16 flags)
+/* return true if anything changed, false otherwise */
+static bool __vlan_add_flags(struct net_bridge_vlan *v, u16 flags)
{
struct net_bridge_vlan_group *vg;
+ u16 old_flags = v->flags;
+ bool ret;

if (br_vlan_is_master(v))
vg = br_vlan_group(v->br);
@@ -60,14 +67,16 @@ static void __vlan_add_flags(struct net_bridge_vlan *v, u16 flags)
vg = nbp_vlan_group(v->port);

if (flags & BRIDGE_VLAN_INFO_PVID)
- __vlan_add_pvid(vg, v->vid);
+ ret = __vlan_add_pvid(vg, v->vid);
else
- __vlan_delete_pvid(vg, v->vid);
+ ret = __vlan_delete_pvid(vg, v->vid);

if (flags & BRIDGE_VLAN_INFO_UNTAGGED)
v->flags |= BRIDGE_VLAN_INFO_UNTAGGED;
else
v->flags &= ~BRIDGE_VLAN_INFO_UNTAGGED;
+
+ return ret || !!(old_flags ^ v->flags);
}

static int __vlan_vid_add(struct net_device *dev, struct net_bridge *br,
@@ -234,7 +243,7 @@ static int __vlan_add(struct net_bridge_vlan *v, u16 flags)
if (flags & BRIDGE_VLAN_INFO_MASTER) {
err = br_vlan_add(br, v->vid, flags |
BRIDGE_VLAN_INFO_BRENTRY);
- if (err)
+ if (err && err != -EEXIST)
goto out_filt;
}

@@ -562,6 +571,7 @@ int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
vg = br_vlan_group(br);
vlan = br_vlan_find(vg, vid);
if (vlan) {
+ ret = -EEXIST;
if (!br_vlan_is_brentry(vlan)) {
/* Trying to change flags of non-existent bridge vlan */
if (!(flags & BRIDGE_VLAN_INFO_BRENTRY))
@@ -577,8 +587,10 @@ int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
vlan->flags |= BRIDGE_VLAN_INFO_BRENTRY;
vg->num_vlans++;
}
- __vlan_add_flags(vlan, flags);
- return 0;
+ if (__vlan_add_flags(vlan, flags))
+ ret = 0;
+
+ return ret;
}

vlan = kzalloc(sizeof(*vlan), GFP_KERNEL);
@@ -870,7 +882,7 @@ int __br_vlan_set_default_pvid(struct net_bridge *br, u16 pvid)
err = nbp_vlan_add(p, pvid,
BRIDGE_VLAN_INFO_PVID |
BRIDGE_VLAN_INFO_UNTAGGED);
- if (err)
+ if (err && err != -EEXIST)
goto err_port;
nbp_vlan_delete(p, old_pvid);
set_bit(p->port_no, changed);
@@ -1037,7 +1049,9 @@ int nbp_vlan_add(struct net_bridge_port *port, u16 vid, u16 flags)
ret = switchdev_port_obj_add(port->dev, &v.obj);
if (ret && ret != -EOPNOTSUPP)
return ret;
- __vlan_add_flags(vlan, flags);
+ if (!__vlan_add_flags(vlan, flags))
+ return -EEXIST;
+
return 0;
}
--
2.1.4
Nikolay Aleksandrov
2017-10-19 16:10:11 UTC
Permalink
Post by Nikolay Aleksandrov
Hi,
Before this set the bridge would generate a notification on vlan add or del
even if they didn't actually do any changes, which confuses listeners and
is generally not preferred. We could also lose notifications on actual
changes if one adds a range of vlans and there's an error in the middle.
The problem with just breaking and returning an error is that we could
break existing user-space scripts which rely on the vlan delete to clear
all existing entries in the specified range and ignore the non-existing
errors (typically used to clear the current vlan config).
So in order to make the notifications more accurate while keeping backwards
compatibility we add a boolean that tracks if anything actually changed
during the config calls.
The vlan add is more difficult to fix because it always returns 0 even if
nothing changed, so we use EEXIST to signal that and in order not to break
overlapping vlan range add or script return expectations we clear it on
return, the functions used by vlan add are not expected to return EEXIST.
Thanks,
Nik
bridge: netlink: make setlink/dellink notifications more accurate
bridge: vlan: return EEXIST on add if nothing changed
net/bridge/br_netlink.c | 49 ++++++++++++++++++++++++++----------------
net/bridge/br_netlink_tunnel.c | 14 +++++++-----
net/bridge/br_private_tunnel.h | 3 ++-
net/bridge/br_vlan.c | 38 +++++++++++++++++++++-----------
4 files changed, 68 insertions(+), 36 deletions(-)
Self-NAK
Dave, please ignore this set and apologies for the noise.

I'd actually prefer to send "changed" down to vlan_add and vlan_del
to be set there instead of overloading EEXIST like that. It will be safer.

I'll wait for some comments about the rest of the change and will send
a v2.

Thanks,
Nik
David Miller
2017-10-22 00:45:18 UTC
Permalink
From: Nikolay Aleksandrov <***@cumulusnetworks.com>
Date: Thu, 19 Oct 2017 19:10:11 +0300
Post by Nikolay Aleksandrov
Self-NAK
Dave, please ignore this set and apologies for the noise.
OK

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