linux-kernel - Re: [PATCH v3 1/3] wifi: rtw88: Move register access from rtw_bf

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Date:   Sun, 2 Apr 2023 13:30:27 +0200
From:   "Linux regression tracking #adding (Thorsten Leemhuis)" 
        <regressions@...mhuis.info>
To:     Sascha Hauer <s.hauer@...gutronix.de>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     linux-wireless@...r.kernel.org, tony0620emma@...il.com,
        kvalo@...nel.org, pkshih@...ltek.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Linux kernel regressions list <regressions@...ts.linux.dev>
Subject: Re: [PATCH v3 1/3] wifi: rtw88: Move register access from
 rtw_bf_assoc() outside the RCU

[CCing the regression list, as it should be in the loop for regressions:
https://docs.kernel.org/admin-guide/reporting-regressions.html]

On 31.03.23 14:59, Sascha Hauer wrote:
> On Sun, Jan 08, 2023 at 10:13:22PM +0100, Martin Blumenstingl wrote:
>> USB and (upcoming) SDIO support may sleep in the read/write handlers.
>> Shrink the RCU critical section so it only cover the call to
>> ieee80211_find_sta() and finding the ic_vht_cap/vht_cap based on the
>> found station. This moves the chip's BFEE configuration outside the
>> rcu_read_lock section and thus prevent "scheduling while atomic" or
>> "Voluntary context switch within RCU read-side critical section!"
>> warnings when accessing the registers using an SDIO card (which is
>> where this issue has been spotted in the real world - but it also
>> affects USB cards).
> 
> Unfortunately this introduces a regression on my RTW8821CU chip. With
> this it constantly looses connection to the AP and reconnects shortly
> after:

Thanks for the report. To be sure the issue doesn't fall through the
cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
tracking bot:

#regzbot ^introduced c7eca79def44
#regzbot title net: wifi: rtw88: RTW8821CU constantly looses connection
to the AP and reconnects shortly after
#regzbot ignore-activity

This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
That page also explains what to do if mails like this annoy you.