RE: [PATCH RFC v1 5/7] rtw88: Configure the registers from rtw_bf_assoc() outside the RCU lock
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From: Pkshih <pkshih@realtek.com>
Date: 2021-07-19 05:47:29
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-----Original Message----- From: Martin Blumenstingl [mailto:martin.blumenstingl@googlemail.com] Sent: Sunday, July 18, 2021 4:41 AM To: linux-wireless@vger.kernel.org Cc: tony0620emma@gmail.com; kvalo@codeaurora.org; johannes@sipsolutions.net; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Neo Jou; Jernej Skrabec; Martin Blumenstingl Subject: [PATCH RFC v1 5/7] rtw88: Configure the registers from rtw_bf_assoc() outside the RCU lock Upcoming SDIO support may sleep in the read/write handlers. Configure the chip's BFEE configuration set from rtw_bf_assoc() outside the rcu_read_lock section to prevent a "scheduling while atomic" issue. Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> --- drivers/net/wireless/realtek/rtw88/bf.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)diff --git a/drivers/net/wireless/realtek/rtw88/bf.c b/drivers/net/wireless/realtek/rtw88/bf.c index aff70e4ae028..06034d5d6f6c 100644 --- a/drivers/net/wireless/realtek/rtw88/bf.c +++ b/drivers/net/wireless/realtek/rtw88/bf.c@@ -39,6 +39,7 @@ void rtw_bf_assoc(struct rtw_dev *rtwdev, struct ieee80211_vif *vif, struct ieee80211_sta_vht_cap *vht_cap; struct ieee80211_sta_vht_cap *ic_vht_cap; const u8 *bssid = bss_conf->bssid; + bool config_bfee = false; u32 sound_dim; u8 i;
The rcu_read_lock() in this function is used to access ieee80211_find_sta() and protect 'sta'.
A simple way is to shrink the critical section, like:
rcu_read_lock();
sta = ieee80211_find_sta(vif, bssid);
if (!sta) {
rtw_warn(rtwdev, "failed to find station entry for bss %pM\n",
bssid);
rcu_read_unlock();
}
vht_cap = &sta->vht_cap;
rcu_read_unlock();
--
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