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From: Johannes Berg <johannes@sipsolutions.net>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	linux-wireless@vger.kernel.org
Cc: tony0620emma@gmail.com, kvalo@codeaurora.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Neo Jou <neojou@gmail.com>,
	Jernej Skrabec <jernej.skrabec@gmail.com>
Subject: Re: [PATCH RFC v1 3/7] rtw88: Use rtw_iterate_stas where the iterator reads or writes registers
Date: Mon, 19 Jul 2021 08:36:04 +0200	[thread overview]
Message-ID: <27d8246ef3c9755b3e6e908188ca36f7b0fab3fc.camel@sipsolutions.net> (raw)
In-Reply-To: <20210717204057.67495-4-martin.blumenstingl@googlemail.com>

On Sat, 2021-07-17 at 22:40 +0200, Martin Blumenstingl wrote:
> 
> --- a/drivers/net/wireless/realtek/rtw88/mac80211.c
> +++ b/drivers/net/wireless/realtek/rtw88/mac80211.c
> @@ -721,7 +721,7 @@ static void rtw_ra_mask_info_update(struct rtw_dev *rtwdev,
>  	br_data.rtwdev = rtwdev;
>  	br_data.vif = vif;
>  	br_data.mask = mask;
> -	rtw_iterate_stas_atomic(rtwdev, rtw_ra_mask_info_update_iter, &br_data);
> +	rtw_iterate_stas(rtwdev, rtw_ra_mask_info_update_iter, &br_data);

And then you pretty much immediately break that invariant here, namely
that you're calling this within the set_bitrate_mask() method called by
mac80211.

That's not actually fundamentally broken today, but it does *severely*
restrict what we can do in mac80211 wrt. locking, and I really don't
want to keep the dozen or so locks forever, this needs simplification
because clearly we don't even know what should be under what lock.

So like I said on the other patch, I don't have a fundamental objection
to taking such a patch, but the locking mess that this gets us into is
something I'd rather not have.

Maybe just don't support set_bitrate_mask for SDIO drivers for now?

The other cases look OK, it's being called from outside contexts
(wowlan, etc.)

johannes


  reply	other threads:[~2021-07-19  6:36 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-17 20:40 [PATCH RFC v1 0/7] rtw88: prepare locking for SDIO support Martin Blumenstingl
2021-07-17 20:40 ` [PATCH RFC v1 1/7] mac80211: Add stations iterator where the iterator function may sleep Martin Blumenstingl
2021-07-19  5:46   ` Pkshih
2021-07-19  6:30   ` Johannes Berg
2021-07-17 20:40 ` [PATCH RFC v1 2/7] rtw88: Use rtw_iterate_vifs where the iterator reads or writes registers Martin Blumenstingl
2021-07-19  5:47   ` Pkshih
2021-07-25 21:31     ` Martin Blumenstingl
2021-07-26  7:22       ` Pkshih
2021-07-17 20:40 ` [PATCH RFC v1 3/7] rtw88: Use rtw_iterate_stas " Martin Blumenstingl
2021-07-19  6:36   ` Johannes Berg [this message]
2021-07-25 21:51     ` Martin Blumenstingl
2021-07-26  7:22       ` Pkshih
2021-08-09 20:00         ` Johannes Berg
2021-07-17 20:40 ` [PATCH RFC v1 4/7] rtw88: Replace usage of rtw_iterate_keys_rcu() with rtw_iterate_keys() Martin Blumenstingl
2021-07-17 20:40 ` [PATCH RFC v1 5/7] rtw88: Configure the registers from rtw_bf_assoc() outside the RCU lock Martin Blumenstingl
2021-07-19  5:47   ` Pkshih
2021-07-25 21:36     ` Martin Blumenstingl
2021-07-26  7:22       ` Pkshih
2021-07-17 20:40 ` [PATCH RFC v1 6/7] rtw88: hci: Convert rf_lock from a spinlock to a mutex Martin Blumenstingl
2021-07-17 20:40 ` [PATCH RFC v1 7/7] rtw88: fw: Convert h2c.lock " Martin Blumenstingl
2021-07-19  5:52 ` [PATCH RFC v1 0/7] rtw88: prepare locking for SDIO support Pkshih

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