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Subject[PATCH 7/9] rtw88: Configure the registers from rtw_bf_assoc() outside the RCU lock
Date
Upcoming SDIO support may sleep in the read/write handlers. Shrink the
RCU critical section so it only cover the ieee80211_find_sta() call 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 a "scheduling while atomic" issue when accessing the registers
using an SDIO card.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
v1 -> v2:
- shrink the critical section as suggested by Ping-Ke

drivers/net/wireless/realtek/rtw88/bf.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/bf.c b/drivers/net/wireless/realtek/rtw88/bf.c
index df750b3a35e9..792eb9930269 100644
--- a/drivers/net/wireless/realtek/rtw88/bf.c
+++ b/drivers/net/wireless/realtek/rtw88/bf.c
@@ -49,19 +49,23 @@ void rtw_bf_assoc(struct rtw_dev *rtwdev, struct ieee80211_vif *vif,

sta = ieee80211_find_sta(vif, bssid);
if (!sta) {
+ rcu_read_unlock();
+
rtw_warn(rtwdev, "failed to find station entry for bss %pM\n",
bssid);
- goto out_unlock;
+ return;
}

ic_vht_cap = &hw->wiphy->bands[NL80211_BAND_5GHZ]->vht_cap;
vht_cap = &sta->vht_cap;

+ rcu_read_unlock();
+
if ((ic_vht_cap->cap & IEEE80211_VHT_CAP_MU_BEAMFORMEE_CAPABLE) &&
(vht_cap->cap & IEEE80211_VHT_CAP_MU_BEAMFORMER_CAPABLE)) {
if (bfinfo->bfer_mu_cnt >= chip->bfer_mu_max_num) {
rtw_dbg(rtwdev, RTW_DBG_BF, "mu bfer number over limit\n");
- goto out_unlock;
+ return;
}

ether_addr_copy(bfee->mac_addr, bssid);
@@ -75,7 +79,7 @@ void rtw_bf_assoc(struct rtw_dev *rtwdev, struct ieee80211_vif *vif,
(vht_cap->cap & IEEE80211_VHT_CAP_SU_BEAMFORMER_CAPABLE)) {
if (bfinfo->bfer_su_cnt >= chip->bfer_su_max_num) {
rtw_dbg(rtwdev, RTW_DBG_BF, "su bfer number over limit\n");
- goto out_unlock;
+ return;
}

sound_dim = vht_cap->cap &
@@ -98,9 +102,6 @@ void rtw_bf_assoc(struct rtw_dev *rtwdev, struct ieee80211_vif *vif,

rtw_chip_config_bfee(rtwdev, rtwvif, bfee, true);
}
-
-out_unlock:
- rcu_read_unlock();
}

void rtw_bf_init_bfer_entry_mu(struct rtw_dev *rtwdev,
--
2.34.1
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