linux-kernel - Re: [PATCH wireless-next] wifi: ath12k: allocate dummy net

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Date: Tue, 7 May 2024 04:47:52 -0700
From: Breno Leitao <leitao@...ian.org>
To: Simon Horman <horms@...nel.org>
Cc: Kalle Valo <kvalo@...nel.org>, Jeff Johnson <jjohnson@...nel.org>,
	netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
	ath12k@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH wireless-next] wifi: ath12k: allocate dummy net_device
 dynamically

On Sat, May 04, 2024 at 03:55:23PM +0100, Simon Horman wrote:
> On Fri, May 03, 2024 at 03:04:39AM -0700, Breno Leitao wrote:
> > Embedding net_device into structures prohibits the usage of flexible
> > arrays in the net_device structure. For more details, see the discussion
> > at [1].
> > 
> > Un-embed the net_device from struct ath12k_ext_irq_grp by converting it
> > into a pointer. Then use the leverage alloc_netdev_dummy() to allocate
> > the net_device object at ath12k_pci_ext_irq_config().
> > 
> > The free of the device occurs at ath12k_pci_free_ext_irq().
> > 
> > [1] https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/
> > 
> > This is *very* similar to the same changes in ath11k commit
> > bca592ead82528b ("wifi: ath11k: allocate dummy net_device dynamically")
> > 
> > Signed-off-by: Breno Leitao <leitao@...ian.org>
> 
> ...
> 
> > diff --git a/drivers/net/wireless/ath/ath12k/pci.c b/drivers/net/wireless/ath/ath12k/pci.c
> 
> ...
> 
> > @@ -577,8 +578,11 @@ static int ath12k_pci_ext_irq_config(struct ath12k_base *ab)
> >  
> >  		irq_grp->ab = ab;
> >  		irq_grp->grp_id = i;
> > -		init_dummy_netdev(&irq_grp->napi_ndev);
> > -		netif_napi_add(&irq_grp->napi_ndev, &irq_grp->napi,
> > +		irq_grp->napi_ndev = alloc_netdev_dummy(0);
> > +		if (!irq_grp->napi_ndev)
> > +			return -ENOMEM;
> 
> Hi Breno,
> 
> Will returning on error here leak resources allocated by
> alloc_netdev_dummy() in previous iterations of this loop?

very good catch. Thanks!

> If so, I suggest jumping to unwind handling which
> can be shared with the error path in the hunk below.

Agree. let me spend some time and propose a V2.

Thanks