[PATCH net-next v2 0/2] net: stmmac: Report RSS as not supported

[PATCH net-next v2 0/2] net: stmmac: Report RSS as not supported

[Maxime Chevallier]

Hi everyone,

This is V2 of an RSS cleanup for stmmac, discovered while running the
rss kselftests on stmmac. It returns bogus indirection tables and key
sizes, when RSS isn't actually available at all.

RSS is currently not supported on any stmmac devices upstream, so
code that was already useless is now effectively dead. It has been the
case since 2019 when the code was added, as platforms need to set rss_en
in their plat data, and no glue ever did that.

Russell King ran a poll in february 2026 [1] asking if the code should
be dropped, without any reply going in either direction.

Jitendra Vegiraju from Broadcom sent 9 iterations of a Broadcom PCIe glue
driver [2] that actually sets rss_en = 1, so there's some hope that this
may be used in the future.

[1]: https://lore.kernel.org/netdev/aYd4BkAeNW6d0iIC@shell.armlinux.org.uk/
[2]: https://lore.kernel.org/netdev/20260402213629.1996133-1-jitendra.vegiraju@broadcom.com/

Nvidia platforms seem to be RSS capable, but it's not going to work out
of the box. Let's leave the feature there for now, with proper -EOPNOTSUPP
returned for RSS ops.

V2:
 - target net-next
 - Add a dedicated helper, following Nicolai's review.

V1: https://lore.kernel.org/netdev/20260926093343.292181-1-maxime.chevallier@bootlin.com/#t

Maxime Chevallier (2):
  net: stmmac: Introduce a helper to check RSS support
  net: stmmac: Don't set or get RSS parameters when not supported

 drivers/net/ethernet/stmicro/stmmac/stmmac.h         |  5 +++++
 drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c | 12 ++++++++++++
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c    |  4 ++--
 3 files changed, 19 insertions(+), 2 deletions(-)

-- 
2.55.0

[PATCH net-next v2 1/2] net: stmmac: Introduce a helper to check RSS support

[Maxime Chevallier]

The RSS feature is only available in stmmac if the hardware reports it
through the DMA caps and if the platform glue sets rss_en.

Introduce a helper that checks both.

For now, no platform sets rss_en, but there's interest in the topic so
leave the door open instead of dropping the feature altogether.

No functional changes intended.

Suggested-by: Nicolai Buchwitz <nb@tipi-net.de>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac.h      | 5 +++++
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index 7582fca63741..e2873d46e049 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -433,6 +433,11 @@ struct timespec64 stmmac_calc_tas_basetime(ktime_t old_base_time,
 					   ktime_t current_time,
 					   u64 cycle_time);
 
+static inline bool stmmac_rss_is_supported(const struct stmmac_priv *priv)
+{
+	return priv->dma_cap.rssen && priv->plat->rss_en;
+}
+
 #if IS_ENABLED(CONFIG_STMMAC_SELFTESTS)
 void stmmac_selftest_run(struct net_device *dev,
 			 struct ethtool_test *etest, u64 *buf);
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 4dee3542df3b..08feb18d62ba 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3538,7 +3538,7 @@ static void stmmac_mac_config_rx_queues_routing(struct stmmac_priv *priv)
 
 static void stmmac_mac_config_rss(struct stmmac_priv *priv)
 {
-	if (!priv->dma_cap.rssen || !priv->plat->rss_en) {
+	if (!stmmac_rss_is_supported(priv)) {
 		priv->rss.enable = false;
 		return;
 	}
@@ -8037,7 +8037,7 @@ static int __stmmac_dvr_probe(struct device *device,
 	for (i = 0; i < ARRAY_SIZE(priv->rss.table); i++)
 		priv->rss.table[i] = ethtool_rxfh_indir_default(i, rxq);
 
-	if (priv->dma_cap.rssen && priv->plat->rss_en)
+	if (stmmac_rss_is_supported(priv))
 		ndev->features |= NETIF_F_RXHASH;
 
 	ndev->vlan_features |= ndev->features;
-- 
2.55.0

Re: [PATCH net-next v2 1/2] net: stmmac: Introduce a helper to check RSS support

[Joe Damato]

On Mon, Sep 28, 2026 at 04:50:41PM +0200, Maxime Chevallier wrote:
> The RSS feature is only available in stmmac if the hardware reports it
> through the DMA caps and if the platform glue sets rss_en.
> 
> Introduce a helper that checks both.
> 
> For now, no platform sets rss_en, but there's interest in the topic so
> leave the door open instead of dropping the feature altogether.
> 
> No functional changes intended.
> 
> Suggested-by: Nicolai Buchwitz <nb@tipi-net.de>
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac.h      | 5 +++++
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
>  2 files changed, 7 insertions(+), 2 deletions(-)

Reviewed-by: Joe Damato <joe@dama.to>

Re: [PATCH net-next v2 1/2] net: stmmac: Introduce a helper to check RSS support

[Lorenzo Bianconi]

[-- Attachment #1: Type: text/plain, Size: 2470 bytes --]

> The RSS feature is only available in stmmac if the hardware reports it
> through the DMA caps and if the platform glue sets rss_en.
> 
> Introduce a helper that checks both.
> 
> For now, no platform sets rss_en, but there's interest in the topic so
> leave the door open instead of dropping the feature altogether.
> 
> No functional changes intended.
> 
> Suggested-by: Nicolai Buchwitz <nb@tipi-net.de>
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

Acked-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>

> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac.h      | 5 +++++
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++--
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> index 7582fca63741..e2873d46e049 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> @@ -433,6 +433,11 @@ struct timespec64 stmmac_calc_tas_basetime(ktime_t old_base_time,
>  					   ktime_t current_time,
>  					   u64 cycle_time);
>  
> +static inline bool stmmac_rss_is_supported(const struct stmmac_priv *priv)
> +{
> +	return priv->dma_cap.rssen && priv->plat->rss_en;
> +}
> +
>  #if IS_ENABLED(CONFIG_STMMAC_SELFTESTS)
>  void stmmac_selftest_run(struct net_device *dev,
>  			 struct ethtool_test *etest, u64 *buf);
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 4dee3542df3b..08feb18d62ba 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -3538,7 +3538,7 @@ static void stmmac_mac_config_rx_queues_routing(struct stmmac_priv *priv)
>  
>  static void stmmac_mac_config_rss(struct stmmac_priv *priv)
>  {
> -	if (!priv->dma_cap.rssen || !priv->plat->rss_en) {
> +	if (!stmmac_rss_is_supported(priv)) {
>  		priv->rss.enable = false;
>  		return;
>  	}
> @@ -8037,7 +8037,7 @@ static int __stmmac_dvr_probe(struct device *device,
>  	for (i = 0; i < ARRAY_SIZE(priv->rss.table); i++)
>  		priv->rss.table[i] = ethtool_rxfh_indir_default(i, rxq);
>  
> -	if (priv->dma_cap.rssen && priv->plat->rss_en)
> +	if (stmmac_rss_is_supported(priv))
>  		ndev->features |= NETIF_F_RXHASH;
>  
>  	ndev->vlan_features |= ndev->features;
> -- 
> 2.55.0
> 
> 

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[PATCH net-next v2 2/2] net: stmmac: Don't set or get RSS parameters when not supported

[Maxime Chevallier]

The RSS kselftests fail on stmmac, and this is partly due to the driver
reporting bogus data for the RSS ops :

 - ethtool -x reports an indirection table and a key while the hardware
   doesn't have any of that
 - ethtool -X fails with -EINVAL.

Let's return early in the rss ops if we know the hardware and platform
don't support RSS.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
index 154cc0c7623d..b78dc301d70d 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
@@ -927,6 +927,9 @@ static u32 stmmac_get_rxfh_key_size(struct net_device *dev)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
 
+	if (!stmmac_rss_is_supported(priv))
+		return 0;
+
 	return sizeof(priv->rss.key);
 }
 
@@ -934,6 +937,9 @@ static u32 stmmac_get_rxfh_indir_size(struct net_device *dev)
 {
 	struct stmmac_priv *priv = netdev_priv(dev);
 
+	if (!stmmac_rss_is_supported(priv))
+		return 0;
+
 	return ARRAY_SIZE(priv->rss.table);
 }
 
@@ -943,6 +949,9 @@ static int stmmac_get_rxfh(struct net_device *dev,
 	struct stmmac_priv *priv = netdev_priv(dev);
 	int i;
 
+	if (!stmmac_rss_is_supported(priv))
+		return -EOPNOTSUPP;
+
 	if (rxfh->indir) {
 		for (i = 0; i < ARRAY_SIZE(priv->rss.table); i++)
 			rxfh->indir[i] = priv->rss.table[i];
@@ -962,6 +971,9 @@ static int stmmac_set_rxfh(struct net_device *dev,
 	struct stmmac_priv *priv = netdev_priv(dev);
 	int i;
 
+	if (!stmmac_rss_is_supported(priv))
+		return -EOPNOTSUPP;
+
 	if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE &&
 	    rxfh->hfunc != ETH_RSS_HASH_TOP)
 		return -EOPNOTSUPP;
-- 
2.55.0

Re: [PATCH net-next v2 2/2] net: stmmac: Don't set or get RSS parameters when not supported

[Joe Damato]

On Mon, Sep 28, 2026 at 04:50:42PM +0200, Maxime Chevallier wrote:
> The RSS kselftests fail on stmmac, and this is partly due to the driver
> reporting bogus data for the RSS ops :
> 
>  - ethtool -x reports an indirection table and a key while the hardware
>    doesn't have any of that
>  - ethtool -X fails with -EINVAL.
> 
> Let's return early in the rss ops if we know the hardware and platform
> don't support RSS.
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>

Reviewed-by: Joe Damato <joe@dama.to>

Re: [PATCH net-next v2 2/2] net: stmmac: Don't set or get RSS parameters when not supported

[Lorenzo Bianconi]

[-- Attachment #1: Type: text/plain, Size: 2123 bytes --]

> The RSS kselftests fail on stmmac, and this is partly due to the driver
> reporting bogus data for the RSS ops :
> 
>  - ethtool -x reports an indirection table and a key while the hardware
>    doesn't have any of that
>  - ethtool -X fails with -EINVAL.
> 
> Let's return early in the rss ops if we know the hardware and platform
> don't support RSS.
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

Acked-by: Lorenzo Bianconi <lorenzo.bianconi@oss.qualcomm.com>

> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> index 154cc0c7623d..b78dc301d70d 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> @@ -927,6 +927,9 @@ static u32 stmmac_get_rxfh_key_size(struct net_device *dev)
>  {
>  	struct stmmac_priv *priv = netdev_priv(dev);
>  
> +	if (!stmmac_rss_is_supported(priv))
> +		return 0;
> +
>  	return sizeof(priv->rss.key);
>  }
>  
> @@ -934,6 +937,9 @@ static u32 stmmac_get_rxfh_indir_size(struct net_device *dev)
>  {
>  	struct stmmac_priv *priv = netdev_priv(dev);
>  
> +	if (!stmmac_rss_is_supported(priv))
> +		return 0;
> +
>  	return ARRAY_SIZE(priv->rss.table);
>  }
>  
> @@ -943,6 +949,9 @@ static int stmmac_get_rxfh(struct net_device *dev,
>  	struct stmmac_priv *priv = netdev_priv(dev);
>  	int i;
>  
> +	if (!stmmac_rss_is_supported(priv))
> +		return -EOPNOTSUPP;
> +
>  	if (rxfh->indir) {
>  		for (i = 0; i < ARRAY_SIZE(priv->rss.table); i++)
>  			rxfh->indir[i] = priv->rss.table[i];
> @@ -962,6 +971,9 @@ static int stmmac_set_rxfh(struct net_device *dev,
>  	struct stmmac_priv *priv = netdev_priv(dev);
>  	int i;
>  
> +	if (!stmmac_rss_is_supported(priv))
> +		return -EOPNOTSUPP;
> +
>  	if (rxfh->hfunc != ETH_RSS_HASH_NO_CHANGE &&
>  	    rxfh->hfunc != ETH_RSS_HASH_TOP)
>  		return -EOPNOTSUPP;
> -- 
> 2.55.0
> 
> 

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Re: [PATCH net-next v2 2/2] net: stmmac: Don't set or get RSS parameters when not supported

[netdev-bot+sashiko]

Thank you for your contribution! Sashiko AI review found 2 potential
issue(s) to consider.

Critical: 0 · High: 0 · Medium: 1 · Low: 1

If you believe none of the issues are legitimate, please reply to each
issue of Medium severity or higher and explain why the AI is wrong.
If any of them are legitimate and you plan to respin, please let patchwork
know by including "pw-bot: cr" as a separate line at the end of your reply
(one such reply per series is enough).

- [Medium] This patch makes stmmac_get_rxfh() in
  drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c return…
- [Low] The commit message describes a user-visible bug: on stmmac
  devices without RSS, 'ethtool -x reports an indirection table and a…

--

net: stmmac: Don't set or get RSS parameters when not supported

This commit changes the stmmac ethtool RSS ops to return early when
stmmac_rss_is_supported() is false. The key and indirection sizes now
report 0, and get_rxfh/set_rxfh return -EOPNOTSUPP. The aim is to stop
reporting bogus RSS data and to make the RSS kselftests work on stmmac.

> The RSS kselftests fail on stmmac, and this is partly due to the driver
> reporting bogus data for the RSS ops :
>
>  - ethtool -x reports an indirection table and a key while the hardware
>    doesn't have any of that
>  - ethtool -X fails with -EINVAL.
>
> Let's return early in the rss ops if we know the hardware and platform
> don't support RSS.
>
> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

[Severity: Low]
The commit message describes a bug that users can see, but there is no
Fixes: tag.

Blame shows that the unconditional stmmac_get_rxfh_key_size(),
stmmac_get_rxfh_indir_size(), stmmac_get_rxfh() and stmmac_set_rxfh()
logic came from commit 76067459c686. The later refactor fb6e30a72539 only
moved these functions to the ethtool_rxfh_param API.

Should this carry the following tag?

Fixes: 76067459c686 ("net: stmmac: Implement RSS and enable it in XGMAC core")

> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> index 1cf0f8820b33..56019683f399 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c

[ ... ]

> @@ -943,6 +949,9 @@ static int stmmac_get_rxfh(struct net_device *dev,
>  	struct stmmac_priv *priv = netdev_priv(dev);
>  	int i;
>  
> +	if (!stmmac_rss_is_supported(priv))
> +		return -EOPNOTSUPP;
> +

[Severity: Medium]
Does this -EOPNOTSUPP break namespace-wide ETHTOOL_MSG_RSS_GET dumps?

rss_dump_one_dev() in net/ethtool/rss.c only skips a device when it has
no get_rxfh op, and stmmac still provides one:

net/ethtool/rss.c:rss_dump_one_dev() {
    ...
	if (!dev->ethtool_ops->get_rxfh)
		return 0;

	if (!ctx->ctx_idx) {
		ret = rss_dump_one_ctx(skb, cb, dev, 0);
		if (ret)
			return ret;
    ...
}

The error then comes back through this path:

ethnl_rss_dumpit()
  rss_dump_one_dev()
    rss_dump_one_ctx()
      rss_prepare()
        rss_prepare_get()
          ops->get_rxfh() -> stmmac_get_rxfh() returns -EOPNOTSUPP

When it reaches ethnl_rss_dumpit(), the loop stops:

	for_each_netdev_lock_ops_compat_scoped(net, dev, ctx->ifindex) {
		...
		ret = rss_dump_one_dev(skb, cb, dev);
		if (ret)
			break;
	}

	return ret;

So the dump fails at the stmmac netdev, and no device with a higher
ifindex gets reported. That includes NICs that do support RSS.

No in-tree platform sets plat->rss_en. The only match is the declaration
in include/linux/stmmac.h. That means stmmac_rss_is_supported() is false
for every in-tree stmmac device.

Before this patch, stmmac_get_rxfh() always returned 0. The dump used to
complete, even though it reported bogus data.

The RSS selftests use this dump path. In
tools/testing/selftests/drivers/net/hw/rss_ctx.py,
test_rss_context_dump() calls:

    ctxs = cfg.ethnl.rss_get({}, dump=True)

It also runs a dump with {'start-context': 1}. On a test host that has a
stmmac port plus the NIC under test, would these now fail, when they
passed before?

mvpp2 and mvneta already return -EOPNOTSUPP from get_rxfh, so the core
already stopped dumps this way. This patch applies that behaviour to every
in-tree stmmac device.

Would it be better to have rss_dump_one_dev() skip devices whose get_rxfh
returns -EOPNOTSUPP, or that report zero indir and key sizes? Another
option is to not provide the stmmac get_rxfh op when RSS is unsupported.

>  	if (rxfh->indir) {
>  		for (i = 0; i < ARRAY_SIZE(priv->rss.table); i++)
>  			rxfh->indir[i] = priv->rss.table[i];

[ ... ]

-- 
Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260928145043.1228968-1-maxime.chevallier%40bootlin.com

Re: [PATCH net-next v2 2/2] net: stmmac: Don't set or get RSS parameters when not supported

[Maxime Chevallier]

On 9/29/26 10:48, netdev-bot+sashiko@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 2 potential
> issue(s) to consider.
> 
> Critical: 0 · High: 0 · Medium: 1 · Low: 1
> 
> If you believe none of the issues are legitimate, please reply to each
> issue of Medium severity or higher and explain why the AI is wrong.
> If any of them are legitimate and you plan to respin, please let patchwork
> know by including "pw-bot: cr" as a separate line at the end of your reply
> (one such reply per series is enough).
> 
> - [Medium] This patch makes stmmac_get_rxfh() in
>   drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c return…
> - [Low] The commit message describes a user-visible bug: on stmmac
>   devices without RSS, 'ethtool -x reports an indirection table and a…
> 
> --
> 
> net: stmmac: Don't set or get RSS parameters when not supported
> 
> This commit changes the stmmac ethtool RSS ops to return early when
> stmmac_rss_is_supported() is false. The key and indirection sizes now
> report 0, and get_rxfh/set_rxfh return -EOPNOTSUPP. The aim is to stop
> reporting bogus RSS data and to make the RSS kselftests work on stmmac.
> 
>> The RSS kselftests fail on stmmac, and this is partly due to the driver
>> reporting bogus data for the RSS ops :
>>
>>  - ethtool -x reports an indirection table and a key while the hardware
>>    doesn't have any of that
>>  - ethtool -X fails with -EINVAL.
>>
>> Let's return early in the rss ops if we know the hardware and platform
>> don't support RSS.
>>
>> Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
> 
> [Severity: Low]
> The commit message describes a bug that users can see, but there is no
> Fixes: tag.
> 
> Blame shows that the unconditional stmmac_get_rxfh_key_size(),
> stmmac_get_rxfh_indir_size(), stmmac_get_rxfh() and stmmac_set_rxfh()
> logic came from commit 76067459c686. The later refactor fb6e30a72539 only
> moved these functions to the ethtool_rxfh_param API.
> 
> Should this carry the following tag?
> 
> Fixes: 76067459c686 ("net: stmmac: Implement RSS and enable it in XGMAC core")

targetting net-next, problem always existed, doesn't crash the kernel,
it's just returning bogus harmless stuff

> 
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
>> index 1cf0f8820b33..56019683f399 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
> 
> [ ... ]
> 
>> @@ -943,6 +949,9 @@ static int stmmac_get_rxfh(struct net_device *dev,
>>  	struct stmmac_priv *priv = netdev_priv(dev);
>>  	int i;
>>  
>> +	if (!stmmac_rss_is_supported(priv))
>> +		return -EOPNOTSUPP;
>> +
> 
> [Severity: Medium]
> Does this -EOPNOTSUPP break namespace-wide ETHTOOL_MSG_RSS_GET dumps?

This was reported by Nicolai already, and other drivers report -EOPNOTSUPP
here.

If we address that, I'd say we do that in the RSS ethnl code.

Maxime

Re: [PATCH net-next v2 2/2] net: stmmac: Don't set or get RSS parameters when not supported

[Jakub Kicinski]

On Tue, 29 Sep 2026 10:57:10 +0200 Maxime Chevallier wrote:
> >> @@ -943,6 +949,9 @@ static int stmmac_get_rxfh(struct net_device *dev,
> >>  	struct stmmac_priv *priv = netdev_priv(dev);
> >>  	int i;
> >>  
> >> +	if (!stmmac_rss_is_supported(priv))
> >> +		return -EOPNOTSUPP;
> >> +  
> > 
> > [Severity: Medium]
> > Does this -EOPNOTSUPP break namespace-wide ETHTOOL_MSG_RSS_GET dumps?  
> 
> This was reported by Nicolai already, and other drivers report -EOPNOTSUPP
> here.
> 
> If we address that, I'd say we do that in the RSS ethnl code.

Let's get this in the same series, cause I'm not 100% convinced.
My instinct is that returning 0 size for indir table and key
would be correct and less hairy for the core to handle.
All pieces of RSS are optional so returning 0 size for everything
should be equivalent to having no RSS.
-- 
pw-bot: cr

Re: [PATCH net-next v2 2/2] net: stmmac: Don't set or get RSS parameters when not supported

[Maxime Chevallier]

Hi Jakub,

On 9/30/26 03:09, Jakub Kicinski wrote:
> On Tue, 29 Sep 2026 10:57:10 +0200 Maxime Chevallier wrote:
>>>> @@ -943,6 +949,9 @@ static int stmmac_get_rxfh(struct net_device *dev,
>>>>  	struct stmmac_priv *priv = netdev_priv(dev);
>>>>  	int i;
>>>>  
>>>> +	if (!stmmac_rss_is_supported(priv))
>>>> +		return -EOPNOTSUPP;
>>>> +  
>>>
>>> [Severity: Medium]
>>> Does this -EOPNOTSUPP break namespace-wide ETHTOOL_MSG_RSS_GET dumps?  
>>
>> This was reported by Nicolai already, and other drivers report -EOPNOTSUPP
>> here.
>>
>> If we address that, I'd say we do that in the RSS ethnl code.
> 
> Let's get this in the same series, cause I'm not 100% convinced.
> My instinct is that returning 0 size for indir table and key
> would be correct and less hairy for the core to handle.
> All pieces of RSS are optional so returning 0 size for everything
> should be equivalent to having no RSS.

Ok no problem, I'll also give it a test on mvpp2 as well then.

Thanks,

Maxime