Re: [PATCH net] net: stmmac: fix invalid usage of irq_set_affinity_hint

[Robin Murphy <robin.murphy@arm.com>]

On 2022-09-14 02:51, Qingfang DENG wrote:
> The cpumask should not be a local variable, since its pointer is saved
> to irq_desc and may be accessed from procfs.
> To fix it, store cpumask to the heap.

FWIW, by the look of it you might be able to use cpumask_of() and not 
store anything at all.

Robin.

> Fixes: 8deec94c6040 ("net: stmmac: set IRQ affinity hint for multi MSI vectors")
> Signed-off-by: Qingfang DENG <dqfext@gmail.com>
> ---
>   drivers/net/ethernet/stmicro/stmmac/stmmac.h      |  2 ++
>   drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 15 ++++++++-------
>   2 files changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> index bdbf86cb102a..720e9f2a40d8 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
> @@ -77,6 +77,7 @@ struct stmmac_tx_queue {
>   	dma_addr_t dma_tx_phy;
>   	dma_addr_t tx_tail_addr;
>   	u32 mss;
> +	cpumask_t cpu_mask;
>   };
>   
>   struct stmmac_rx_buffer {
> @@ -114,6 +115,7 @@ struct stmmac_rx_queue {
>   		unsigned int len;
>   		unsigned int error;
>   	} state;
> +	cpumask_t cpu_mask;
>   };
>   
>   struct stmmac_channel {
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 8418e795cc21..7b1c1be998e3 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -3469,7 +3469,6 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev)
>   {
>   	struct stmmac_priv *priv = netdev_priv(dev);
>   	enum request_irq_err irq_err;
> -	cpumask_t cpu_mask;
>   	int irq_idx = 0;
>   	char *int_name;
>   	int ret;
> @@ -3580,9 +3579,10 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev)
>   			irq_idx = i;
>   			goto irq_error;
>   		}
> -		cpumask_clear(&cpu_mask);
> -		cpumask_set_cpu(i % num_online_cpus(), &cpu_mask);
> -		irq_set_affinity_hint(priv->rx_irq[i], &cpu_mask);
> +		cpumask_set_cpu(i % num_online_cpus(),
> +				&priv->dma_conf.rx_queue[i].cpu_mask);
> +		irq_set_affinity_hint(priv->rx_irq[i],
> +				      &priv->dma_conf.rx_queue[i].cpu_mask);
>   	}
>   
>   	/* Request Tx MSI irq */
> @@ -3605,9 +3605,10 @@ static int stmmac_request_irq_multi_msi(struct net_device *dev)
>   			irq_idx = i;
>   			goto irq_error;
>   		}
> -		cpumask_clear(&cpu_mask);
> -		cpumask_set_cpu(i % num_online_cpus(), &cpu_mask);
> -		irq_set_affinity_hint(priv->tx_irq[i], &cpu_mask);
> +		cpumask_set_cpu(i % num_online_cpus(),
> +				&priv->dma_conf.tx_queue[i].cpu_mask);
> +		irq_set_affinity_hint(priv->tx_irq[i],
> +				      &priv->dma_conf.tx_queue[i].cpu_mask);
>   	}
>   
>   	return 0;