[PATCH net-next] net: bridge: switchdev: allow port isolation to be offloaded

[PATCH net-next] net: bridge: switchdev: allow port isolation to be offloaded

[DENG Qingfang]

Add BR_ISOLATED flag to BR_PORT_FLAGS_HW_OFFLOAD, to allow switchdev
drivers to offload port isolation.

Suggested-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: DENG Qingfang <dqfext@gmail.com>
---
 net/bridge/br_switchdev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
index 6bf518d78f02..898257153883 100644
--- a/net/bridge/br_switchdev.c
+++ b/net/bridge/br_switchdev.c
@@ -71,7 +71,8 @@ bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
 
 /* Flags that can be offloaded to hardware */
 #define BR_PORT_FLAGS_HW_OFFLOAD (BR_LEARNING | BR_FLOOD | \
-				  BR_MCAST_FLOOD | BR_BCAST_FLOOD)
+				  BR_MCAST_FLOOD | BR_BCAST_FLOOD | \
+				  BR_ISOLATED)
 
 int br_switchdev_set_port_flag(struct net_bridge_port *p,
 			       unsigned long flags,
-- 
2.25.1

Re: [PATCH net-next] net: bridge: switchdev: allow port isolation to be offloaded

[Ido Schimmel]

On Wed, Aug 11, 2021 at 09:52:46PM +0800, DENG Qingfang wrote:
> Add BR_ISOLATED flag to BR_PORT_FLAGS_HW_OFFLOAD, to allow switchdev
> drivers to offload port isolation.
> 
> Suggested-by: Vladimir Oltean <olteanv@gmail.com>
> Signed-off-by: DENG Qingfang <dqfext@gmail.com>
> ---
>  net/bridge/br_switchdev.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
> index 6bf518d78f02..898257153883 100644
> --- a/net/bridge/br_switchdev.c
> +++ b/net/bridge/br_switchdev.c
> @@ -71,7 +71,8 @@ bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
>  
>  /* Flags that can be offloaded to hardware */
>  #define BR_PORT_FLAGS_HW_OFFLOAD (BR_LEARNING | BR_FLOOD | \
> -				  BR_MCAST_FLOOD | BR_BCAST_FLOOD)
> +				  BR_MCAST_FLOOD | BR_BCAST_FLOOD | \
> +				  BR_ISOLATED)

Why add it now and not as part of a patchset that actually makes use of
the flag in a driver that offloads port isolation?

>  
>  int br_switchdev_set_port_flag(struct net_bridge_port *p,
>  			       unsigned long flags,
> -- 
> 2.25.1
> 

Re: [PATCH net-next] net: bridge: switchdev: allow port isolation to be offloaded

[Vladimir Oltean]

On Thu, Aug 12, 2021 at 12:38:56AM +0300, Ido Schimmel wrote:
> On Wed, Aug 11, 2021 at 09:52:46PM +0800, DENG Qingfang wrote:
> > Add BR_ISOLATED flag to BR_PORT_FLAGS_HW_OFFLOAD, to allow switchdev
> > drivers to offload port isolation.
> >
> > Suggested-by: Vladimir Oltean <olteanv@gmail.com>
> > Signed-off-by: DENG Qingfang <dqfext@gmail.com>
> > ---
> >  net/bridge/br_switchdev.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
> > index 6bf518d78f02..898257153883 100644
> > --- a/net/bridge/br_switchdev.c
> > +++ b/net/bridge/br_switchdev.c
> > @@ -71,7 +71,8 @@ bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
> >
> >  /* Flags that can be offloaded to hardware */
> >  #define BR_PORT_FLAGS_HW_OFFLOAD (BR_LEARNING | BR_FLOOD | \
> > -				  BR_MCAST_FLOOD | BR_BCAST_FLOOD)
> > +				  BR_MCAST_FLOOD | BR_BCAST_FLOOD | \
> > +				  BR_ISOLATED)
>
> Why add it now and not as part of a patchset that actually makes use of
> the flag in a driver that offloads port isolation?

The way the information got transmitted is a bit unfortunate.

Making BR_ISOLATED part of BR_PORT_FLAGS_HW_OFFLOAD is a matter of
correctness when switchdev offloads the data path. Since this feature
will not work correctly without driver intervention, it makes sense that
drivers should reject it currently, which is exactly what this patch
accomplishes - it makes the code path go through the
SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS driver handlers, which return
-EINVAL for everything they don't recognize.

(yes, we do still have a problem for drivers that don't catch
SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS at all, switchdev will return
-EOPNOTSUPP for those which is then ignored, but those are in the
minority)

Re: [PATCH net-next] net: bridge: switchdev: allow port isolation to be offloaded

[Ido Schimmel]

On Thu, Aug 12, 2021 at 12:45:06AM +0300, Vladimir Oltean wrote:
> On Thu, Aug 12, 2021 at 12:38:56AM +0300, Ido Schimmel wrote:
> > On Wed, Aug 11, 2021 at 09:52:46PM +0800, DENG Qingfang wrote:
> > > Add BR_ISOLATED flag to BR_PORT_FLAGS_HW_OFFLOAD, to allow switchdev
> > > drivers to offload port isolation.
> > >
> > > Suggested-by: Vladimir Oltean <olteanv@gmail.com>
> > > Signed-off-by: DENG Qingfang <dqfext@gmail.com>
> > > ---
> > >  net/bridge/br_switchdev.c | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
> > > index 6bf518d78f02..898257153883 100644
> > > --- a/net/bridge/br_switchdev.c
> > > +++ b/net/bridge/br_switchdev.c
> > > @@ -71,7 +71,8 @@ bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
> > >
> > >  /* Flags that can be offloaded to hardware */
> > >  #define BR_PORT_FLAGS_HW_OFFLOAD (BR_LEARNING | BR_FLOOD | \
> > > -				  BR_MCAST_FLOOD | BR_BCAST_FLOOD)
> > > +				  BR_MCAST_FLOOD | BR_BCAST_FLOOD | \
> > > +				  BR_ISOLATED)
> >
> > Why add it now and not as part of a patchset that actually makes use of
> > the flag in a driver that offloads port isolation?
> 
> The way the information got transmitted is a bit unfortunate.
> 
> Making BR_ISOLATED part of BR_PORT_FLAGS_HW_OFFLOAD is a matter of
> correctness when switchdev offloads the data path. Since this feature
> will not work correctly without driver intervention, it makes sense that
> drivers should reject it currently, which is exactly what this patch
> accomplishes - it makes the code path go through the
> SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS driver handlers, which return
> -EINVAL for everything they don't recognize.

If the purpose is correctness, then this is not the only flag that was
missed. BR_HAIRPIN_MODE is also relevant for the data path, for example.

Anyway, the commit message needs to be reworded to reflect the true
purpose of the patch.

> 
> (yes, we do still have a problem for drivers that don't catch
> SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS at all, switchdev will return
> -EOPNOTSUPP for those which is then ignored, but those are in the
> minority)

Re: [PATCH net-next] net: bridge: switchdev: allow port isolation to be offloaded

[Vladimir Oltean]

On Thu, Aug 12, 2021 at 12:52:48AM +0300, Ido Schimmel wrote:
> On Thu, Aug 12, 2021 at 12:45:06AM +0300, Vladimir Oltean wrote:
> > On Thu, Aug 12, 2021 at 12:38:56AM +0300, Ido Schimmel wrote:
> > > On Wed, Aug 11, 2021 at 09:52:46PM +0800, DENG Qingfang wrote:
> > > > Add BR_ISOLATED flag to BR_PORT_FLAGS_HW_OFFLOAD, to allow switchdev
> > > > drivers to offload port isolation.
> > > >
> > > > Suggested-by: Vladimir Oltean <olteanv@gmail.com>
> > > > Signed-off-by: DENG Qingfang <dqfext@gmail.com>
> > > > ---
> > > >  net/bridge/br_switchdev.c | 3 ++-
> > > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
> > > > index 6bf518d78f02..898257153883 100644
> > > > --- a/net/bridge/br_switchdev.c
> > > > +++ b/net/bridge/br_switchdev.c
> > > > @@ -71,7 +71,8 @@ bool nbp_switchdev_allowed_egress(const struct net_bridge_port *p,
> > > >
> > > >  /* Flags that can be offloaded to hardware */
> > > >  #define BR_PORT_FLAGS_HW_OFFLOAD (BR_LEARNING | BR_FLOOD | \
> > > > -				  BR_MCAST_FLOOD | BR_BCAST_FLOOD)
> > > > +				  BR_MCAST_FLOOD | BR_BCAST_FLOOD | \
> > > > +				  BR_ISOLATED)
> > >
> > > Why add it now and not as part of a patchset that actually makes use of
> > > the flag in a driver that offloads port isolation?
> > 
> > The way the information got transmitted is a bit unfortunate.
> > 
> > Making BR_ISOLATED part of BR_PORT_FLAGS_HW_OFFLOAD is a matter of
> > correctness when switchdev offloads the data path. Since this feature
> > will not work correctly without driver intervention, it makes sense that
> > drivers should reject it currently, which is exactly what this patch
> > accomplishes - it makes the code path go through the
> > SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS driver handlers, which return
> > -EINVAL for everything they don't recognize.
> 
> If the purpose is correctness, then this is not the only flag that was
> missed. BR_HAIRPIN_MODE is also relevant for the data path, for example.

I never wanted to suggest that I'm giving a comprehensive answer, I just
answered Qingfang's punctual question here:
https://lore.kernel.org/netdev/CALW65jbotyW0MSOd-bd1TH_mkiBWhhRCQ29jgn+d12rXdj2pZA@mail.gmail.com/

Tobias also pointed out the same issue about BR_MULTICAST_TO_UNICAST in
conjunction with tx_fwd_offload (although the same is probably true even
without it):
https://patchwork.kernel.org/project/netdevbpf/cover/20210426170411.1789186-1-tobias@waldekranz.com/

> Anyway, the commit message needs to be reworded to reflect the true
> purpose of the patch.

Agree, and potentially extended with all the bridge port flags which are
broken without switchdev driver intervention.

Re: [PATCH net-next] net: bridge: switchdev: allow port isolation to be offloaded

[DENG Qingfang]

On Thu, Aug 12, 2021 at 12:58:33AM +0300, Vladimir Oltean wrote:
> On Thu, Aug 12, 2021 at 12:52:48AM +0300, Ido Schimmel wrote:
> > 
> > If the purpose is correctness, then this is not the only flag that was
> > missed. BR_HAIRPIN_MODE is also relevant for the data path, for example.
> 
> I never wanted to suggest that I'm giving a comprehensive answer, I just
> answered Qingfang's punctual question here:
> https://lore.kernel.org/netdev/CALW65jbotyW0MSOd-bd1TH_mkiBWhhRCQ29jgn+d12rXdj2pZA@mail.gmail.com/
> 
> Tobias also pointed out the same issue about BR_MULTICAST_TO_UNICAST in
> conjunction with tx_fwd_offload (although the same is probably true even
> without it):
> https://patchwork.kernel.org/project/netdevbpf/cover/20210426170411.1789186-1-tobias@waldekranz.com/
> 
> > Anyway, the commit message needs to be reworded to reflect the true
> > purpose of the patch.
> 
> Agree, and potentially extended with all the bridge port flags which are
> broken without switchdev driver intervention.

So, what else flags should be added to BR_PORT_FLAGS_HW_OFFLOAD?

Re: [PATCH net-next] net: bridge: switchdev: allow port isolation to be offloaded

[Vladimir Oltean]

On Thu, Aug 12, 2021 at 02:04:10PM +0800, DENG Qingfang wrote:
> On Thu, Aug 12, 2021 at 12:58:33AM +0300, Vladimir Oltean wrote:
> > On Thu, Aug 12, 2021 at 12:52:48AM +0300, Ido Schimmel wrote:
> > >
> > > If the purpose is correctness, then this is not the only flag that was
> > > missed. BR_HAIRPIN_MODE is also relevant for the data path, for example.
> >
> > I never wanted to suggest that I'm giving a comprehensive answer, I just
> > answered Qingfang's punctual question here:
> > https://lore.kernel.org/netdev/CALW65jbotyW0MSOd-bd1TH_mkiBWhhRCQ29jgn+d12rXdj2pZA@mail.gmail.com/
> >
> > Tobias also pointed out the same issue about BR_MULTICAST_TO_UNICAST in
> > conjunction with tx_fwd_offload (although the same is probably true even
> > without it):
> > https://patchwork.kernel.org/project/netdevbpf/cover/20210426170411.1789186-1-tobias@waldekranz.com/
> >
> > > Anyway, the commit message needs to be reworded to reflect the true
> > > purpose of the patch.
> >
> > Agree, and potentially extended with all the bridge port flags which are
> > broken without switchdev driver intervention.
>
> So, what else flags should be added to BR_PORT_FLAGS_HW_OFFLOAD?

I can't think of others beside these 3, BR_ISOLATED, BR_HAIRPIN_MODE and BR_MULTICAST_TO_UNICAST.