linux-kernel - Re: [PATCH v10 3/3] Bluetooth: NXP: Add protocol support for NXP Bluetooth chipsets

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Date:   Tue, 14 Mar 2023 17:33:59 +0100
From:   Simon Horman <simon.horman@...igine.com>
To:     Neeraj sanjay kale <neeraj.sanjaykale@....com>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "marcel@...tmann.org" <marcel@...tmann.org>,
        "johan.hedberg@...il.com" <johan.hedberg@...il.com>,
        "luiz.dentz@...il.com" <luiz.dentz@...il.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "jirislaby@...nel.org" <jirislaby@...nel.org>,
        "alok.a.tiwari@...cle.com" <alok.a.tiwari@...cle.com>,
        "hdanton@...a.com" <hdanton@...a.com>,
        "ilpo.jarvinen@...ux.intel.com" <ilpo.jarvinen@...ux.intel.com>,
        "leon@...nel.org" <leon@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        Amitkumar Karwar <amitkumar.karwar@....com>,
        Rohit Fule <rohit.fule@....com>,
        Sherry Sun <sherry.sun@....com>
Subject: Re: [PATCH v10 3/3] Bluetooth: NXP: Add protocol support for NXP
 Bluetooth chipsets

On Tue, Mar 14, 2023 at 03:40:34PM +0000, Neeraj sanjay kale wrote:
> Hi Simon
> 
> Thank you for reviewing the patch. I have a comment below:
> 
> > 
> > > +send_skb:
> > > +     /* Prepend skb with frame type */
> > > +     memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);
> > > +     skb_queue_tail(&nxpdev->txq, skb);
> > > +
> > > +     btnxpuart_tx_wakeup(nxpdev);
> > > +ret:
> > > +     return 0;
> > > +
> > > +free_skb:
> > > +     kfree_skb(skb);
> > > +     goto ret;
> > 
> > nit: I think it would be nicer to simply return 0 here.
> >      And remove the ret label entirely.
> > 
> > > +}
> > 
> We need to return from this function without clearing the skbs, unless "goto free_skb" is called.
> If I remove the ret label and return after kfree_skb() it causes a kernel crash.
> Keeping this change as it is.
> 
> Please let me know if you have any further review comments on the v11 patch.

I'll look over v11.

But for the record, I meant something like this:

send_skb:
     /* Prepend skb with frame type */
     memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);
     skb_queue_tail(&nxpdev->txq, skb);

     btnxpuart_tx_wakeup(nxpdev);
     return 0;

free_skb:
     kfree_skb(skb);
     return 0;
}

> We need to return from this function without clearing the skbs, unless "goto free_skb" is called.
> If I remove the ret label and return after kfree_skb() it causes a kernel crash.
> Keeping this change as it is.
> 
> Please let me know if you have any further review comments on the v11 patch.