From: Kalle Valo <kvalo@codeaurora.org>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Sumit Garg <sumit.garg@linaro.org>,
linux-wireless@vger.kernel.org, davem@davemloft.net,
kuba@kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, matthias.schoepfer@ithinx.io,
Philipp.Berg@liebherr.com, Michael.Weitner@liebherr.com,
daniel.thompson@linaro.org, loic.poulain@linaro.org,
stable@vger.kernel.org
Subject: Re: [PATCH] mac80211: fix race in ieee80211_register_hw()
Date: Mon, 06 Apr 2020 16:04:57 +0300 [thread overview]
Message-ID: <87imiczrwm.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <a7e3e8cceff1301f5de5fb2c9aac62b372922b3e.camel@sipsolutions.net> (Johannes Berg's message of "Mon, 06 Apr 2020 14:53:49 +0200")
Johannes Berg <johannes@sipsolutions.net> writes:
> On Mon, 2020-04-06 at 15:52 +0300, Kalle Valo wrote:
>> Johannes Berg <johannes@sipsolutions.net> writes:
>>
>> > On Mon, 2020-04-06 at 15:44 +0300, Kalle Valo wrote:
>> > > > user-space ieee80211_register_hw() RX IRQ
>> > > > +++++++++++++++++++++++++++++++++++++++++++++
>> > > > | | |
>> > > > |<---wlan0---wiphy_register() |
>> > > > |----start wlan0---->| |
>> > > > | |<---IRQ---(RX packet)
>> > > > | Kernel crash |
>> > > > | due to unallocated |
>> > > > | workqueue. |
>> >
>> > [snip]
>> >
>> > > I have understood that no frames should be received until mac80211 calls
>> > > struct ieee80211_ops::start:
>> > >
>> > > * @start: Called before the first netdevice attached to the hardware
>> > > * is enabled. This should turn on the hardware and must turn on
>> > > * frame reception (for possibly enabled monitor interfaces.)
>> >
>> > True, but I think he's saying that you can actually add and configure an
>> > interface as soon as the wiphy is registered?
>>
>> With '<---IRQ---(RX packet)' I assumed wcn36xx is delivering a frame to
>> mac80211 using ieee80211_rx(), but of course I'm just guessing here.
>
> Yeah, but that could be legitimate?
Ah, I misunderstood then. The way I have understood is that no rx frames
should be delivered (= calling ieee80211_rx()_ before start() is called,
but if that's not the case please ignore me :)
--
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
next prev parent reply other threads:[~2020-04-06 13:05 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-06 12:21 [PATCH] mac80211: fix race in ieee80211_register_hw() Sumit Garg
2020-04-06 12:44 ` Johannes Berg
2020-04-06 13:00 ` Sumit Garg
2020-04-06 12:44 ` Kalle Valo
2020-04-06 12:47 ` Johannes Berg
2020-04-06 12:52 ` Kalle Valo
2020-04-06 12:53 ` Johannes Berg
2020-04-06 13:04 ` Kalle Valo [this message]
2020-04-06 13:07 ` Johannes Berg
2020-04-06 13:21 ` Sumit Garg
2020-04-06 13:27 ` Kalle Valo
2020-04-06 13:55 ` Krishna Chaitanya
2020-04-06 14:01 ` Johannes Berg
2020-04-06 14:25 ` Krishna Chaitanya
2020-04-06 15:06 ` Johannes Berg
2020-04-06 18:08 ` Krishna Chaitanya
2020-04-07 6:42 ` Sumit Garg
2020-04-06 13:06 ` Sumit Garg
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