linux-kernel - Re: [PATCH 1/2] wifi: ath11k: fix temperature event locking

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Message-ID: <ZTFIlS79DclOOjrS@hovoldconsulting.com>
Date:   Thu, 19 Oct 2023 17:17:41 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Jeff Johnson <quic_jjohnson@...cinc.com>
Cc:     Johan Hovold <johan+linaro@...nel.org>,
        Kalle Valo <kvalo@...nel.org>,
        Pradeep Kumar Chitrapu <quic_pradeepc@...cinc.com>,
        ath11k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 1/2] wifi: ath11k: fix temperature event locking

On Thu, Oct 19, 2023 at 08:04:55AM -0700, Jeff Johnson wrote:
> On 10/19/2023 3:42 AM, Johan Hovold wrote:
> > The ath11k active pdevs are protected by RCU but the temperature event
> > handling code calling ath11k_mac_get_ar_by_pdev_id() was not marked as a
> > read-side critical section as reported by RCU lockdep:
> 
> How do I enable this? Just enable CONFIG_PROVE_RCU?

Yeah, via CONFIG_PROVE_LOCKING.

> Of course I'd also need to exercise the code path...

Right, this one I hit when reading out the sensor temperature (e.g.
using lm_sensors).
 
> > +	rcu_read_lock();
> > +
> >   	ar = ath11k_mac_get_ar_by_pdev_id(ab, ev->pdev_id);
> >   	if (!ar) {
> >   		ath11k_warn(ab, "invalid pdev id in pdev temperature ev %d", ev->pdev_id);
> 
> aren't you missing an unlock() in this error path?
> 
> perhaps have a goto cleanup that does both the unlock() and the kfree()?

Bah, I am, thanks for catching that.

Spent too much time on scanning for further instances that I didn't
check the first one properly. Sorry about that. Will send a v2.

Johan