linux-kernel - Re: [PATCH 05/10] rtw88: Do not access registers while atomic

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Message-ID: <e33aaa2ab60e04d3449273e117ca73acb3895ed3.camel@realtek.com>
Date:   Fri, 20 May 2022 06:06:05 +0000
From:   Pkshih <pkshih@...ltek.com>
To:     "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>
CC:     "johannes@...solutions.net" <johannes@...solutions.net>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "neojou@...il.com" <neojou@...il.com>,
        "kvalo@...nel.org" <kvalo@...nel.org>,
        "tony0620emma@...il.com" <tony0620emma@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "martin.blumenstingl@...glemail.com" 
        <martin.blumenstingl@...glemail.com>,
        "linux@...i-kroll.de" <linux@...i-kroll.de>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH 05/10] rtw88: Do not access registers while atomic

On Wed, 2022-05-18 at 10:23 +0200, Sascha Hauer wrote:
> The driver uses ieee80211_iterate_active_interfaces_atomic()
> and ieee80211_iterate_stations_atomic() in several places and does
> register accesses in the iterators. This doesn't cope with upcoming
                                           ^^^^^^^ does?
> USB support as registers can only be accessed non-atomically.
> 
> Split these into a two stage process: First use the atomic iterator
> functions to collect all active interfaces or stations on a list, then
> iterate over the list non-atomically and call the iterator on each
> entry.

I think the subject could be "iterate over vif/sta list non-atomically"

> 
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> Suggested-by: Pkshih <pkshih@...ltek.com>
> ---
>  drivers/net/wireless/realtek/rtw88/phy.c  |  6 +-
>  drivers/net/wireless/realtek/rtw88/ps.c   |  2 +-
>  drivers/net/wireless/realtek/rtw88/util.c | 92 +++++++++++++++++++++++
>  drivers/net/wireless/realtek/rtw88/util.h | 12 ++-
>  4 files changed, 105 insertions(+), 7 deletions(-)
> 
> 

[...]

>  
> diff --git a/drivers/net/wireless/realtek/rtw88/util.c b/drivers/net/wireless/realtek/rtw88/util.c
> index 2c515af214e76..db55dbd5c533e 100644
> --- a/drivers/net/wireless/realtek/rtw88/util.c
> +++ b/drivers/net/wireless/realtek/rtw88/util.c
> @@ -105,3 +105,95 @@ void rtw_desc_to_mcsrate(u16 rate, u8 *mcs, u8 *nss)
>  		*mcs = rate - DESC_RATEMCS0;
>  	}
>  }
> 

[...]

> +
> +void rtw_iterate_stas(struct rtw_dev *rtwdev,
> +		      void (*iterator)(void *data,
> +				       struct ieee80211_sta *sta),
> +				       void *data)
> +{
> +	struct rtw_iter_stas_data iter_data;
> +	struct rtw_stas_entry *sta_entry, *tmp;

lockdep_assert_held(&rtwdev->mutex);

> +
> +	iter_data.rtwdev = rtwdev;
> +	INIT_LIST_HEAD(&iter_data.list);
> +
> +	ieee80211_iterate_stations_atomic(rtwdev->hw, rtw_collect_sta_iter,
> +					  &iter_data);
> +
> +	list_for_each_entry_safe(sta_entry, tmp, &iter_data.list,
> +				 list) {
> +		list_del_init(&sta_entry->list);
> +		iterator(data, sta_entry->sta);
> +		kfree(sta_entry);
> +	}
> +}
> +

[...]

> +void rtw_iterate_vifs(struct rtw_dev *rtwdev,
> +		      void (*iterator)(void *data, u8 *mac,
> +				       struct ieee80211_vif *vif),
> +		      void *data)
> +{
> +	struct rtw_iter_vifs_data iter_data;
> +	struct rtw_vifs_entry *vif_entry, *tmp;

lockdep_assert_held(&rtwdev->mutex);

> +
> +	iter_data.rtwdev = rtwdev;
> +	INIT_LIST_HEAD(&iter_data.list);
> +
> +	ieee80211_iterate_active_interfaces_atomic(rtwdev->hw,
> +			IEEE80211_IFACE_ITER_NORMAL, rtw_collect_vif_iter, &iter_data);
> +
> +	list_for_each_entry_safe(vif_entry, tmp, &iter_data.list,
> +				 list) {
> +		list_del_init(&vif_entry->list);
> +		iterator(data, vif_entry->mac, vif_entry->vif);
> +		kfree(vif_entry);
> +	}
> +}
> 

[...]

--
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