Re: [PATCH net-next v6 04/12] net: airoha: Move airoha_qdma pointer in airoha_gdm_dev struct

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] `airoha_update_hw_stats` uses `spin_lock` instead of `spin_lock_bh`, risking a deadlock.
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commit 15d9ae36a0700634235a620ca1a28c53959a5c30
Author: Lorenzo Bianconi <lorenzo@kernel.org>

net: airoha: Move airoha_qdma pointer in airoha_gdm_dev struct

This commit moves the airoha_qdma pointer from the airoha_gdm_port struct
to the airoha_gdm_dev struct. This is a preliminary change to support
multiple net_devices connected to the same port via an external hardware
arbiter.

> diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
> index 18a89de4d58ab..e0cd401bbf672 100644
> --- a/drivers/net/ethernet/airoha/airoha_eth.c
> +++ b/drivers/net/ethernet/airoha/airoha_eth.c
[ ... ]
> @@ -1562,9 +1566,10 @@ static void airoha_qdma_stop_napi(struct airoha_qdma *qdma)
>  	}
>  }
>  
> -static void airoha_update_hw_stats(struct airoha_gdm_port *port)
> +static void airoha_update_hw_stats(struct airoha_gdm_dev *dev)
>  {
> -	struct airoha_eth *eth = port->qdma->eth;
> +	struct airoha_gdm_port *port = dev->port;
> +	struct airoha_eth *eth = dev->eth;
>  	u32 val, i = 0;
>  
>  	spin_lock(&port->stats.lock);

This isn't a regression introduced by this patch, but is it safe to use
spin_lock() here instead of spin_lock_bh()?

Since airoha_update_hw_stats() is called from ndo_get_stats64() which can be
invoked from softirq context (e.g., via tc actions or bpf), and also from
process context (e.g., via ethtool operations), could a process thread holding
this lock without disabling bottom halves be preempted by a softirq on the
same CPU that also attempts to call ndo_get_stats64(), leading to a deadlock?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260511-airoha-eth-multi-serdes-v6-0-c899462c4f75@kernel.org?part=4