| Message ID | 20250302162137.698092-1-maxime.chevallier@bootlin.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] net: ethtool: Set the req_info->dev on DUMP requests for each dev | expand |
On Sun, 2 Mar 2025 17:21:36 +0100 Maxime Chevallier <maxime.chevallier@bootlin.com> wrote: > There are a few netlink commands that rely on the req_info->dev field > being populated by ethnl in their ->prepare_data() and ->fill_reply(). > > For a regular GET request, this will be set by ethnl_default_parse(), > which calls ethnl_parse_header_dev_get(). > > In the case of a DUMP request, the ->prepare_data() and ->fill_reply() > callbacks will be called with the req_info->dev being NULL, which can > cause discrepancies in the behaviour between GET and DUMP results. > > The main impact is that ethnl_req_get_phydev() will not find any > phy_device, impacting : > - plca > - pse-pd > - stats > > Some other commands rely on req_info->dev, namely : > - coalesce in ->fill_reply to look for an irq_moder > > Although cable_test and tunnels also rely on req_info->dev being set, > that's not a problem for these commands as : > - cable_test doesn't support DUMP > - tunnels rolls its own ->dumpit (and sets dev in the req_info). > - phy also has its own ->dumpit > > All other commands use reply_data->dev (probably the correct way of > doing things) and aren't facing this issue. > > Simply set the dev in the req_info context when iterating to dump each > dev. > > Fixes: c15e065b46dc ("net: ethtool: Allow passing a phy index for some > commands") Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com> > --- > > Fixes tag targets the phy-index commit, as it introduced a change in > behaviour for PLCA. From what I can tell, coalesce never correctly > detected irq_moder in DUMP requests. > > We could also consider fixing all individual commands that use > req_info->dev, however I'm not actually sure it's incorrect to do so, > feel free to correct me though. > > Maxime > > net/ethtool/netlink.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c > index b4c45207fa32..de967961d8fe 100644 > --- a/net/ethtool/netlink.c > +++ b/net/ethtool/netlink.c > @@ -582,6 +582,7 @@ static int ethnl_default_dumpit(struct sk_buff *skb, > dev_hold(dev); > rcu_read_unlock(); > > + ctx->req_info->dev = dev; I would rather put it in ethnl_default_dump_one() before ethnl_init_reply_data() call. With this change: Reviewed-by: Kory Maincent <kory.maincent@bootlin.com> Tested-by: Kory Maincent <kory.maincent@bootlin.com> Thank you! > ret = ethnl_default_dump_one(skb, dev, ctx, > genl_info_dump(cb)); > rcu_read_lock();
Hi Köry, On Tue, 4 Mar 2025 17:00:51 +0100 Kory Maincent <kory.maincent@bootlin.com> wrote: > On Sun, 2 Mar 2025 17:21:36 +0100 > Maxime Chevallier <maxime.chevallier@bootlin.com> wrote: > > > There are a few netlink commands that rely on the req_info->dev field > > being populated by ethnl in their ->prepare_data() and ->fill_reply(). > > > > For a regular GET request, this will be set by ethnl_default_parse(), > > which calls ethnl_parse_header_dev_get(). > > > > In the case of a DUMP request, the ->prepare_data() and ->fill_reply() > > callbacks will be called with the req_info->dev being NULL, which can > > cause discrepancies in the behaviour between GET and DUMP results. > > > > The main impact is that ethnl_req_get_phydev() will not find any > > phy_device, impacting : > > - plca > > - pse-pd > > - stats > > > > Some other commands rely on req_info->dev, namely : > > - coalesce in ->fill_reply to look for an irq_moder > > > > Although cable_test and tunnels also rely on req_info->dev being set, > > that's not a problem for these commands as : > > - cable_test doesn't support DUMP > > - tunnels rolls its own ->dumpit (and sets dev in the req_info). > > - phy also has its own ->dumpit > > > > All other commands use reply_data->dev (probably the correct way of > > doing things) and aren't facing this issue. > > > > Simply set the dev in the req_info context when iterating to dump each > > dev. > > > > Fixes: c15e065b46dc ("net: ethtool: Allow passing a phy index for some > > commands") Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com> > > --- > > > > Fixes tag targets the phy-index commit, as it introduced a change in > > behaviour for PLCA. From what I can tell, coalesce never correctly > > detected irq_moder in DUMP requests. > > > > We could also consider fixing all individual commands that use > > req_info->dev, however I'm not actually sure it's incorrect to do so, > > feel free to correct me though. > > > > Maxime > > > > net/ethtool/netlink.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c > > index b4c45207fa32..de967961d8fe 100644 > > --- a/net/ethtool/netlink.c > > +++ b/net/ethtool/netlink.c > > @@ -582,6 +582,7 @@ static int ethnl_default_dumpit(struct sk_buff *skb, > > dev_hold(dev); > > rcu_read_unlock(); > > > > + ctx->req_info->dev = dev; > > I would rather put it in ethnl_default_dump_one() before > ethnl_init_reply_data() call. Ah yes true, that'll be more consistent with the other callpaths. > With this change: > Reviewed-by: Kory Maincent <kory.maincent@bootlin.com> > Tested-by: Kory Maincent <kory.maincent@bootlin.com> Thank you for testing, I'll respin. Maxime >
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c index b4c45207fa32..de967961d8fe 100644 --- a/net/ethtool/netlink.c +++ b/net/ethtool/netlink.c @@ -582,6 +582,7 @@ static int ethnl_default_dumpit(struct sk_buff *skb, dev_hold(dev); rcu_read_unlock(); + ctx->req_info->dev = dev; ret = ethnl_default_dump_one(skb, dev, ctx, genl_info_dump(cb)); rcu_read_lock();
There are a few netlink commands that rely on the req_info->dev field being populated by ethnl in their ->prepare_data() and ->fill_reply(). For a regular GET request, this will be set by ethnl_default_parse(), which calls ethnl_parse_header_dev_get(). In the case of a DUMP request, the ->prepare_data() and ->fill_reply() callbacks will be called with the req_info->dev being NULL, which can cause discrepancies in the behaviour between GET and DUMP results. The main impact is that ethnl_req_get_phydev() will not find any phy_device, impacting : - plca - pse-pd - stats Some other commands rely on req_info->dev, namely : - coalesce in ->fill_reply to look for an irq_moder Although cable_test and tunnels also rely on req_info->dev being set, that's not a problem for these commands as : - cable_test doesn't support DUMP - tunnels rolls its own ->dumpit (and sets dev in the req_info). - phy also has its own ->dumpit All other commands use reply_data->dev (probably the correct way of doing things) and aren't facing this issue. Simply set the dev in the req_info context when iterating to dump each dev. Fixes: c15e065b46dc ("net: ethtool: Allow passing a phy index for some commands") Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com> --- Fixes tag targets the phy-index commit, as it introduced a change in behaviour for PLCA. From what I can tell, coalesce never correctly detected irq_moder in DUMP requests. We could also consider fixing all individual commands that use req_info->dev, however I'm not actually sure it's incorrect to do so, feel free to correct me though. Maxime net/ethtool/netlink.c | 1 + 1 file changed, 1 insertion(+)