2022-04-16 00:35:53

by Jeff Evanson

Subject: [PATCH 2/2] Trigger proper interrupts in igc_xsk_wakeup

in igc_xsk_wakeup, trigger the proper interrupt based on whether flags
contains XDP_WAKEUP_RX and/or XDP_WAKEUP_TX

Signed-off-by: Jeff Evanson <[email protected]>
---
drivers/net/ethernet/intel/igc/igc_main.c | 36 +++++++++++++++++------
1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index a36a18c84aeb..d706de95dc06 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -6073,7 +6073,7 @@ static void igc_trigger_rxtxq_interrupt(struct igc_adapter *adapter,
int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
{
struct igc_adapter *adapter = netdev_priv(dev);
- struct igc_q_vector *q_vector;
+ struct igc_q_vector *txq_vector = 0, *rxq_vector = 0;
struct igc_ring *ring;

if (test_bit(__IGC_DOWN, &adapter->state))
@@ -6082,17 +6082,35 @@ int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
if (!igc_xdp_is_enabled(adapter))
return -ENXIO;

- if (queue_id >= adapter->num_rx_queues)
- return -EINVAL;
+ if (flags & XDP_WAKEUP_RX) {
+ if (queue_id >= adapter->num_rx_queues)
+ return -EINVAL;

- ring = adapter->rx_ring[queue_id];
+ ring = adapter->rx_ring[queue_id];
+ if (!ring->xsk_pool)
+ return -ENXIO;

- if (!ring->xsk_pool)
- return -ENXIO;
+ rxq_vector = ring->q_vector;
+ }
+
+ if (flags & XDP_WAKEUP_TX) {
+ if (queue_id >= adapter->num_tx_queues)
+ return -EINVAL;
+
+ ring = adapter->tx_ring[queue_id];
+ if (!ring->xsk_pool)
+ return -ENXIO;
+
+ txq_vector = ring->q_vector;
+ }
+
+ if (rxq_vector &&
+ !napi_if_scheduled_mark_missed(&rxq_vector->napi))
+ igc_trigger_rxtxq_interrupt(adapter, rxq_vector);

- q_vector = adapter->q_vector[queue_id];
- if (!napi_if_scheduled_mark_missed(&q_vector->napi))
- igc_trigger_rxtxq_interrupt(adapter, q_vector);
+ if (txq_vector && txq_vector != rxq_vector &&
+ !napi_if_scheduled_mark_missed(&txq_vector->napi))
+ igc_trigger_rxtxq_interrupt(adapter, txq_vector);

return 0;
}
--
2.17.1

2022-04-19 00:01:10

by Jeff Evanson

Subject: RE: [PATCH 2/2] Trigger proper interrupts in igc_xsk_wakeup

Hi Vinicius. Thank you for the reply.

The scenario only happens when the transmit queue interrupt is mapped to a different interrupt from the receive queue. In the case where XDP_WAKEUP_TX is set in the flags argument, the previous code would only trigger the interrupt for the receive queue, causing the transmit queue's napi_struct to never be scheduled.

In the scenario where XDP_WAKEUP_TX and XDP_WAKEUP_RX are both set in flags, the receive interrupt is always triggered and the transmit interrupt is only triggered when the transmit q_vector differs from the receive q_vector.

Regards,
Jeff Evanson

-----Original Message-----
From: Vinicius Costa Gomes <[email protected]>
Sent: Monday, April 18, 2022 11:45 AM
To: Jeff Evanson <[email protected]>; Jesse Brandeburg <[email protected]>; Tony Nguyen <[email protected]>; David S. Miller <[email protected]>; Jakub Kicinski <[email protected]>; [email protected]; [email protected]; [email protected]
Cc: Jeff Evanson <[email protected]>; [email protected]
Subject: Re: [PATCH 2/2] Trigger proper interrupts in igc_xsk_wakeup

-External-

Jeff Evanson <[email protected]> writes:

> in igc_xsk_wakeup, trigger the proper interrupt based on whether flags
> contains XDP_WAKEUP_RX and/or XDP_WAKEUP_TX
>
> Signed-off-by: Jeff Evanson <[email protected]>
> ---
> drivers/net/ethernet/intel/igc/igc_main.c | 36
> +++++++++++++++++------
> 1 file changed, 27 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
> b/drivers/net/ethernet/intel/igc/igc_main.c
> index a36a18c84aeb..d706de95dc06 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -6073,7 +6073,7 @@ static void igc_trigger_rxtxq_interrupt(struct
> igc_adapter *adapter, int igc_xsk_wakeup(struct net_device *dev, u32
> queue_id, u32 flags) {
> struct igc_adapter *adapter = netdev_priv(dev);
> - struct igc_q_vector *q_vector;
> + struct igc_q_vector *txq_vector = 0, *rxq_vector = 0;
> struct igc_ring *ring;
>
> if (test_bit(__IGC_DOWN, &adapter->state)) @@ -6082,17 +6082,35 @@
> int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
> if (!igc_xdp_is_enabled(adapter))
> return -ENXIO;
>
> - if (queue_id >= adapter->num_rx_queues)
> - return -EINVAL;
> + if (flags & XDP_WAKEUP_RX) {
> + if (queue_id >= adapter->num_rx_queues)
> + return -EINVAL;
>
> - ring = adapter->rx_ring[queue_id];
> + ring = adapter->rx_ring[queue_id];
> + if (!ring->xsk_pool)
> + return -ENXIO;
>
> - if (!ring->xsk_pool)
> - return -ENXIO;
> + rxq_vector = ring->q_vector;
> + }
> +
> + if (flags & XDP_WAKEUP_TX) {
> + if (queue_id >= adapter->num_tx_queues)
> + return -EINVAL;
> +
> + ring = adapter->tx_ring[queue_id];
> + if (!ring->xsk_pool)
> + return -ENXIO;
> +
> + txq_vector = ring->q_vector;
> + }
> +
> + if (rxq_vector &&
> + !napi_if_scheduled_mark_missed(&rxq_vector->napi))
> + igc_trigger_rxtxq_interrupt(adapter, rxq_vector);
>
> - q_vector = adapter->q_vector[queue_id];
> - if (!napi_if_scheduled_mark_missed(&q_vector->napi))
> - igc_trigger_rxtxq_interrupt(adapter, q_vector);
> + if (txq_vector && txq_vector != rxq_vector &&
> + !napi_if_scheduled_mark_missed(&txq_vector->napi))
> + igc_trigger_rxtxq_interrupt(adapter, txq_vector);

Two things:
- My imagination was not able to produce a scenario where this commit would solve any problems. Can you explain better the case where the current code would cause the wrong interrupt to be generated (or miss generating an interrupt)? (this should be in the commit message)
- I think that with this patch applied, there would cases (both TX and RX flags set) that we cause two writes into the EICS register. That could cause unnecessary wakeups.

>
> return 0;
> }
> --
> 2.17.1
>

Cheers,
--
Vinicius

2022-04-19 15:53:31

by Vinicius Costa Gomes

Subject: Re: [PATCH 2/2] Trigger proper interrupts in igc_xsk_wakeup

Jeff Evanson <[email protected]> writes:

> in igc_xsk_wakeup, trigger the proper interrupt based on whether flags
> contains XDP_WAKEUP_RX and/or XDP_WAKEUP_TX
>
> Signed-off-by: Jeff Evanson <[email protected]>
> ---
> drivers/net/ethernet/intel/igc/igc_main.c | 36 +++++++++++++++++------
> 1 file changed, 27 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index a36a18c84aeb..d706de95dc06 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -6073,7 +6073,7 @@ static void igc_trigger_rxtxq_interrupt(struct igc_adapter *adapter,
> int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
> {
> struct igc_adapter *adapter = netdev_priv(dev);
> - struct igc_q_vector *q_vector;
> + struct igc_q_vector *txq_vector = 0, *rxq_vector = 0;
> struct igc_ring *ring;
>
> if (test_bit(__IGC_DOWN, &adapter->state))
> @@ -6082,17 +6082,35 @@ int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
> if (!igc_xdp_is_enabled(adapter))
> return -ENXIO;
>
> - if (queue_id >= adapter->num_rx_queues)
> - return -EINVAL;
> + if (flags & XDP_WAKEUP_RX) {
> + if (queue_id >= adapter->num_rx_queues)
> + return -EINVAL;
>
> - ring = adapter->rx_ring[queue_id];
> + ring = adapter->rx_ring[queue_id];
> + if (!ring->xsk_pool)
> + return -ENXIO;
>
> - if (!ring->xsk_pool)
> - return -ENXIO;
> + rxq_vector = ring->q_vector;
> + }
> +
> + if (flags & XDP_WAKEUP_TX) {
> + if (queue_id >= adapter->num_tx_queues)
> + return -EINVAL;
> +
> + ring = adapter->tx_ring[queue_id];
> + if (!ring->xsk_pool)
> + return -ENXIO;
> +
> + txq_vector = ring->q_vector;
> + }
> +
> + if (rxq_vector &&
> + !napi_if_scheduled_mark_missed(&rxq_vector->napi))
> + igc_trigger_rxtxq_interrupt(adapter, rxq_vector);
>
> - q_vector = adapter->q_vector[queue_id];
> - if (!napi_if_scheduled_mark_missed(&q_vector->napi))
> - igc_trigger_rxtxq_interrupt(adapter, q_vector);
> + if (txq_vector && txq_vector != rxq_vector &&
> + !napi_if_scheduled_mark_missed(&txq_vector->napi))
> + igc_trigger_rxtxq_interrupt(adapter, txq_vector);

Two things:
- My imagination was not able to produce a scenario where this commit
would solve any problems. Can you explain better the case where the
current code would cause the wrong interrupt to be generated (or miss
generating an interrupt)? (this should be in the commit message)
- I think that with this patch applied, there would cases (both TX and
RX flags set) that we cause two writes into the EICS register. That
could cause unnecessary wakeups.

>
> return 0;
> }
> --
> 2.17.1
>

Cheers,
--
Vinicius

2022-04-20 14:16:42

by Paul Menzel

Subject: Re: [Intel-wired-lan] [PATCH 2/2] Trigger proper interrupts in igc_xsk_wakeup

Dear Jeff,


Thank you for your patch.


Am 15.04.22 um 23:05 schrieb Jeff Evanson:

1. Add a From tag(?), so your company instead of gmail.com email is used?
2. Please add a prefix to the commit message summary. See `git log
--oneline drivers/net/ethernet/igc` for examples.

> in igc_xsk_wakeup, trigger the proper interrupt based on whether flags
> contains XDP_WAKEUP_RX and/or XDP_WAKEUP_TX

Nit. Please add a dot/period to the end of sentences.

Can you please add a paragraph on what system you experienced the
problem, and how to verify your fix?

> Signed-off-by: Jeff Evanson <[email protected]>
> ---
> drivers/net/ethernet/intel/igc/igc_main.c | 36 +++++++++++++++++------
> 1 file changed, 27 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index a36a18c84aeb..d706de95dc06 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -6073,7 +6073,7 @@ static void igc_trigger_rxtxq_interrupt(struct igc_adapter *adapter,
> int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
> {
> struct igc_adapter *adapter = netdev_priv(dev);
> - struct igc_q_vector *q_vector;
> + struct igc_q_vector *txq_vector = 0, *rxq_vector = 0;

Should you use NULL instead of 0?


Kind regards,

Paul


> struct igc_ring *ring;
>
> if (test_bit(__IGC_DOWN, &adapter->state))
> @@ -6082,17 +6082,35 @@ int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
> if (!igc_xdp_is_enabled(adapter))
> return -ENXIO;
>
> - if (queue_id >= adapter->num_rx_queues)
> - return -EINVAL;
> + if (flags & XDP_WAKEUP_RX) {
> + if (queue_id >= adapter->num_rx_queues)
> + return -EINVAL;
>
> - ring = adapter->rx_ring[queue_id];
> + ring = adapter->rx_ring[queue_id];
> + if (!ring->xsk_pool)
> + return -ENXIO;
>
> - if (!ring->xsk_pool)
> - return -ENXIO;
> + rxq_vector = ring->q_vector;
> + }
> +
> + if (flags & XDP_WAKEUP_TX) {
> + if (queue_id >= adapter->num_tx_queues)
> + return -EINVAL;
> +
> + ring = adapter->tx_ring[queue_id];
> + if (!ring->xsk_pool)
> + return -ENXIO;
> +
> + txq_vector = ring->q_vector;
> + }
> +
> + if (rxq_vector &&
> + !napi_if_scheduled_mark_missed(&rxq_vector->napi))
> + igc_trigger_rxtxq_interrupt(adapter, rxq_vector);
>
> - q_vector = adapter->q_vector[queue_id];
> - if (!napi_if_scheduled_mark_missed(&q_vector->napi))
> - igc_trigger_rxtxq_interrupt(adapter, q_vector);
> + if (txq_vector && txq_vector != rxq_vector &&
> + !napi_if_scheduled_mark_missed(&txq_vector->napi))
> + igc_trigger_rxtxq_interrupt(adapter, txq_vector);
>
> return 0;
> }

2022-04-21 09:09:15

by Paolo Abeni

Subject: Re: [PATCH 2/2] Trigger proper interrupts in igc_xsk_wakeup

On Fri, 2022-04-15 at 15:05 -0600, Jeff Evanson wrote:
> in igc_xsk_wakeup, trigger the proper interrupt based on whether flags
> contains XDP_WAKEUP_RX and/or XDP_WAKEUP_TX
>
> Signed-off-by: Jeff Evanson <[email protected]>
> ---
> drivers/net/ethernet/intel/igc/igc_main.c | 36 +++++++++++++++++------
> 1 file changed, 27 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index a36a18c84aeb..d706de95dc06 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -6073,7 +6073,7 @@ static void igc_trigger_rxtxq_interrupt(struct igc_adapter *adapter,
> int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
> {
> struct igc_adapter *adapter = netdev_priv(dev);
> - struct igc_q_vector *q_vector;
> + struct igc_q_vector *txq_vector = 0, *rxq_vector = 0;

Since a v2 is likely required - see even Vinicius's comments on patch
1/2 - please reorder the above to respect the reverse x-mas tree order
and fix the sparse warning introduced above (s/ = 0/ = NULL/)

Thanks!

Paolo

2022-04-22 01:56:55

by Vinicius Costa Gomes

Subject: RE: [PATCH 2/2] Trigger proper interrupts in igc_xsk_wakeup

Hi Jeff,

Jeff Evanson <[email protected]> writes:

> Hi Vinicius. Thank you for the reply.
>
> The scenario only happens when the transmit queue interrupt is mapped
> to a different interrupt from the receive queue. In the case where
> XDP_WAKEUP_TX is set in the flags argument, the previous code would
> only trigger the interrupt for the receive queue, causing the transmit
> queue's napi_struct to never be scheduled.

This is a good explanation, adding it to the commit message for the v2
would be a good idea.

>
> In the scenario where XDP_WAKEUP_TX and XDP_WAKEUP_RX are both set in
> flags, the receive interrupt is always triggered and the transmit
> interrupt is only triggered when the transmit q_vector differs from
> the receive q_vector.

I missed that condition when I looked at the patch. Sorry about that.
Makes more sense now.

Acked-by: Vinicius Costa Gomes <[email protected]>

>
> Regards,
> Jeff Evanson
>
> -----Original Message-----
> From: Vinicius Costa Gomes <[email protected]>
> Sent: Monday, April 18, 2022 11:45 AM
> To: Jeff Evanson <[email protected]>; Jesse Brandeburg <[email protected]>; Tony Nguyen <[email protected]>; David S. Miller <[email protected]>; Jakub Kicinski <[email protected]>; [email protected]; [email protected]; [email protected]
> Cc: Jeff Evanson <[email protected]>; [email protected]
> Subject: Re: [PATCH 2/2] Trigger proper interrupts in igc_xsk_wakeup
>
> -External-
>
> Jeff Evanson <[email protected]> writes:
>
>> in igc_xsk_wakeup, trigger the proper interrupt based on whether flags
>> contains XDP_WAKEUP_RX and/or XDP_WAKEUP_TX
>>
>> Signed-off-by: Jeff Evanson <[email protected]>
>> ---
>> drivers/net/ethernet/intel/igc/igc_main.c | 36
>> +++++++++++++++++------
>> 1 file changed, 27 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c
>> b/drivers/net/ethernet/intel/igc/igc_main.c
>> index a36a18c84aeb..d706de95dc06 100644
>> --- a/drivers/net/ethernet/intel/igc/igc_main.c
>> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
>> @@ -6073,7 +6073,7 @@ static void igc_trigger_rxtxq_interrupt(struct
>> igc_adapter *adapter, int igc_xsk_wakeup(struct net_device *dev, u32
>> queue_id, u32 flags) {
>> struct igc_adapter *adapter = netdev_priv(dev);
>> - struct igc_q_vector *q_vector;
>> + struct igc_q_vector *txq_vector = 0, *rxq_vector = 0;
>> struct igc_ring *ring;
>>
>> if (test_bit(__IGC_DOWN, &adapter->state)) @@ -6082,17 +6082,35 @@
>> int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
>> if (!igc_xdp_is_enabled(adapter))
>> return -ENXIO;
>>
>> - if (queue_id >= adapter->num_rx_queues)
>> - return -EINVAL;
>> + if (flags & XDP_WAKEUP_RX) {
>> + if (queue_id >= adapter->num_rx_queues)
>> + return -EINVAL;
>>
>> - ring = adapter->rx_ring[queue_id];
>> + ring = adapter->rx_ring[queue_id];
>> + if (!ring->xsk_pool)
>> + return -ENXIO;
>>
>> - if (!ring->xsk_pool)
>> - return -ENXIO;
>> + rxq_vector = ring->q_vector;
>> + }
>> +
>> + if (flags & XDP_WAKEUP_TX) {
>> + if (queue_id >= adapter->num_tx_queues)
>> + return -EINVAL;
>> +
>> + ring = adapter->tx_ring[queue_id];
>> + if (!ring->xsk_pool)
>> + return -ENXIO;
>> +
>> + txq_vector = ring->q_vector;
>> + }
>> +
>> + if (rxq_vector &&
>> + !napi_if_scheduled_mark_missed(&rxq_vector->napi))
>> + igc_trigger_rxtxq_interrupt(adapter, rxq_vector);
>>
>> - q_vector = adapter->q_vector[queue_id];
>> - if (!napi_if_scheduled_mark_missed(&q_vector->napi))
>> - igc_trigger_rxtxq_interrupt(adapter, q_vector);
>> + if (txq_vector && txq_vector != rxq_vector &&
>> + !napi_if_scheduled_mark_missed(&txq_vector->napi))
>> + igc_trigger_rxtxq_interrupt(adapter, txq_vector);
>
> Two things:
> - My imagination was not able to produce a scenario where this commit would solve any problems. Can you explain better the case where the current code would cause the wrong interrupt to be generated (or miss generating an interrupt)? (this should be in the commit message)
> - I think that with this patch applied, there would cases (both TX and RX flags set) that we cause two writes into the EICS register. That could cause unnecessary wakeups.
>
>>
>> return 0;
>> }
>> --
>> 2.17.1
>>
>
> Cheers,
> --
> Vinicius
>

--
Vinicius