Re: [PATCH net-next v9 2/6] net: airoha: Remove private net_device pointer in airoha_gdm_dev struct

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> 
> Pre-existing issues:
> - [High] Potential deadlock in airoha_update_hw_stats() due to use of spin_lock() instead of spin_lock_bh().
> --
> 
> commit d33fdec52e6f77bf6de4ab248729e1a868e78dc6
> Author: Lorenzo Bianconi <lorenzo@kernel.org>
> 
> net: airoha: Remove private net_device pointer in airoha_gdm_dev struct
> 
> This commit removes the redundant net_device pointer from the
> airoha_gdm_dev struct. The code now relies on the netdev_from_priv()
> routine to retrieve the net_device pointer. This is a refactoring change
> with no logical modifications.
> 
> > diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
> > index 6574901ebd19b..57a16de0a2ec7 100644
> > --- a/drivers/net/ethernet/airoha/airoha_eth.c
> > +++ b/drivers/net/ethernet/airoha/airoha_eth.c
> 
> [ ... ]
> 
> [Severity: High]
> This isn't a bug introduced by this patch, but I noticed a potential
> deadlock in airoha_update_hw_stats():
> 
> drivers/net/ethernet/airoha/airoha_eth.c:airoha_update_hw_stats() {
> 	...
> 	spin_lock(&port->stats.lock);
> 	...
> }
> 
> Does this code risk a deadlock? The ndo_get_stats64 callback
> (airoha_dev_get_stats64) can be executed in softirq context, while this
> lock is also acquired from process context (e.g., via ethtool) without
> disabling softirqs.
> 
> If a softirq interrupts the process context reader holding the lock on the
> same CPU, wouldn't it spin forever trying to acquire the same lock? Should
> spin_lock_bh() be used here instead to prevent this?

As pointed out during previous iterations of the series, I do not think this is
a real issue since ndo_get_stats64() callback can't be run in softirq context.
Moreover, the reported issue has not been introduced by this series.

Regards,
Lorenzo

> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/20260603-airoha-eth-multi-serdes-v9-0-5d476bc2f426@kernel.org?part=2

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