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Date:   Mon, 3 May 2021 11:37:18 +0300
From:   Pavel Skripkin <paskripkin@gmail.com>
To:     Johan Hovold <johan@kernel.org>
Cc:     marcel@holtmann.org, johan.hedberg@gmail.com, luiz.dentz@gmail.com,
        linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Rocky Liao <rjliao@codeaurora.org>,
        Matthias Kaehlcke <mka@chromium.org>
Subject: Re: [PATCH] bluetooth: fix potential gfp
Message-ID: <20210503113718.2ec9668f@gmail.com>
In-Reply-To: <YI+s2Hms/56Pvatu@hovoldconsulting.com>
References: <20210501150445.4055-1-paskripkin@gmail.com>
        <YI+s2Hms/56Pvatu@hovoldconsulting.com>
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Hi!

On Mon, 3 May 2021 09:57:12 +0200
Johan Hovold <johan@kernel.org> wrote:
> On Sat, May 01, 2021 at 06:04:45PM +0300, Pavel Skripkin wrote:
> > In qca_power_shutdown() qcadev local variable is
> > initialized by hu->serdev.dev private data, but
> > hu->serdev can be NULL and there is a check for it.
> > 
> > Since, qcadev is not used before
> > 
> > 	if (!hu->serdev)
> > 		return;
> > 
> > we can move its initialization after this "if" to
> > prevent gfp.
> 
> Good catch. The commit message needs to be improved however.
> 
> First, what's a "gfp"? Did you mean GPF?

Yes, it's typo :(

> 
> Second, I'd expect you to try to point to the commit that introduced
> this issue (e.g. using a Fixes tag) and CC the person responsible.
> This appears to be commit 5559904ccc08 ("Bluetooth: hci_qca: Add QCA
> Rome power off support to the qca_power_shutdown()") but you should
> verify that.
> 
> Third, this looks like it could be triggered by user space so you
> should CC stable too so that the fix is backported.
> 
> Fourth, your commit summary (Subject) is missing the driver component
> (i.e. "hci_qca").
>

Ok, I'll fix it all and send v2 soon.

Thanks for your feedback!

> > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
> > ---
> >  drivers/bluetooth/hci_qca.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/bluetooth/hci_qca.c
> > b/drivers/bluetooth/hci_qca.c index de36af63e182..9589ef6c0c26
> > 100644 --- a/drivers/bluetooth/hci_qca.c
> > +++ b/drivers/bluetooth/hci_qca.c
> > @@ -1820,8 +1820,6 @@ static void qca_power_shutdown(struct
> > hci_uart *hu) unsigned long flags;
> >  	enum qca_btsoc_type soc_type = qca_soc_type(hu);
> >  
> > -	qcadev = serdev_device_get_drvdata(hu->serdev);
> > -
> >  	/* From this point we go into power off state. But serial
> > port is
> >  	 * still open, stop queueing the IBS data and flush all
> > the buffered
> >  	 * data in skb's.
> > @@ -1837,6 +1835,8 @@ static void qca_power_shutdown(struct
> > hci_uart *hu) if (!hu->serdev)
> >  		return;
> >  
> > +	qcadev = serdev_device_get_drvdata(hu->serdev);
> > +
> >  	if (qca_is_wcn399x(soc_type)) {
> >  		host_set_baudrate(hu, 2400);
> >  		qca_send_power_pulse(hu, false);
> 
> Johan


With regards,
Pavel Skripkin