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Subject: Re: [PATCH v2 3/3] wifi: ath12k: Add lock to protect the hardware
 state
From: Johannes Berg <johannes@sipsolutions.net>
To: Kalle Valo <kvalo@kernel.org>
Cc: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>, 
	ath12k@lists.infradead.org, linux-wireless@vger.kernel.org
Date: Wed, 24 Apr 2024 11:52:22 +0200
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On Wed, 2024-04-24 at 12:50 +0300, Kalle Valo wrote:
> Johannes Berg <johannes@sipsolutions.net> writes:
>=20
> > On Wed, 2024-04-24 at 12:39 +0300, Kalle Valo wrote:
> > >=20
> > > Exactly. Swithing to use wiphy_lock() definitely one of my longterm
> > > goals in ath12k. I already started working on switching ath12k to use
> > > wiphy_lock() but IIRC I got blocked by not being able to call
> > > wiphy_delayed_work_cancel() without taking wiphy_lock.
> >=20
> > That's because I didn't want to have an async version, but theoreticall=
y
> > we could have a version of it that just cancels the timer. If you don't
> > hold the wiphy mutex already you could even wait for it to finish. It
> > just adds more complexity there, and I was trying to make it all a lot
> > more obvious :)
>=20
> Yeah, understandable. I think changing ath12k WMI event handling to use
> wiphy_work makes sense, running them in tasklet context feels overkill.

Maybe. Note that the wiphy lock _can_ create delays etc. here, if you're
doing other configuration work at the same time, or similar. Though I
guess eventually you need locking there anyway, to access the HW. So it
can be a bit of a trade-off.

I expect this will evolve over time even in mac80211, though so far we
haven't seen any bad effect from it.

johannes