RE: [PATCH v3 0/8] rtw88: prepare locking for SDIO support

[Pkshih <pkshih@realtek.com>]

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> -----Original Message-----
> From: Pkshih
> Sent: Wednesday, January 19, 2022 5:38 PM
> To: 'Martin Blumenstingl' <martin.blumenstingl@googlemail.com>; 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 <neojou@gmail.com>; Jernej Skrabec <jernej.skrabec@gmail.com>; Ed
> Swierk <eswierk@gh.st>
> Subject: RE: [PATCH v3 0/8] rtw88: prepare locking for SDIO support
> 
> Hi,
> 
> > -----Original Message-----
> > From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> > Sent: Saturday, January 8, 2022 8:55 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 <neojou@gmail.com>; Jernej Skrabec <jernej.skrabec@gmail.com>;
> > Pkshih <pkshih@realtek.com>; Ed Swierk <eswierk@gh.st>; Martin Blumenstingl
> > <martin.blumenstingl@googlemail.com>
> > Subject: [PATCH v3 0/8] rtw88: prepare locking for SDIO support
> >
> 
> [...]
> 
> I do stressed test of connection and suspend, and it get stuck after about
> 4 hours but no useful messages. I will re-build my kernel and turn on lockdep debug
> to see if it can tell me what is wrong.
> 

I found some deadlock: 

[ 4891.169653]        CPU0                    CPU1
[ 4891.169732]        ----                    ----
[ 4891.169799]   lock(&rtwdev->mutex);
[ 4891.169874]                                lock(&local->sta_mtx);
[ 4891.169948]                                lock(&rtwdev->mutex);
[ 4891.170050]   lock(&local->sta_mtx);


[ 4919.598630]        CPU0                    CPU1
[ 4919.598715]        ----                    ----
[ 4919.598779]   lock(&local->iflist_mtx);
[ 4919.598900]                                lock(&rtwdev->mutex);
[ 4919.598995]                                lock(&local->iflist_mtx);
[ 4919.599092]   lock(&rtwdev->mutex);

So, I add wrappers to iterate rtw_iterate_stas() and rtw_iterate_vifs() that
use _atomic version to collect sta and vif, and use list_for_each() to iterate.
Reference code is attached, and I'm still thinking if we can have better method.

--
Ping-Ke


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From c9539ea5fbbd692030381a42ad31e08490f5b804 Mon Sep 17 00:00:00 2001
From: Ping-Ke Shih <pkshih@realtek.com>
Date: Fri, 21 Jan 2022 11:09:45 +0800
Subject: [PATCH] rtw88: use atomic to collect stas and does iterators

Change-Id: I7665268d0ca859d4e3c3a60b1f15b76f5444f0ab
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
---
 util.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 util.h | 13 +++++----
 2 files changed, 100 insertions(+), 5 deletions(-)

diff --git a/util.c b/util.c
index 2c515af2..1835968f 100644
--- a/util.c
+++ b/util.c
@@ -105,3 +105,95 @@ void rtw_desc_to_mcsrate(u16 rate, u8 *mcs, u8 *nss)
 		*mcs = rate - DESC_RATEMCS0;
 	}
 }
+
+struct rtw_stas_entry {
+	struct list_head list;
+	struct ieee80211_sta *sta;
+};
+
+struct rtw_iter_stas_data {
+	struct rtw_dev *rtwdev;
+	struct list_head list;
+};
+
+void rtw_collect_sta_iter(void *data, struct ieee80211_sta *sta)
+{
+	struct rtw_iter_stas_data *iter_stas = (struct rtw_iter_stas_data *)data;
+	struct rtw_stas_entry *stas_entry;
+
+	stas_entry = kmalloc(sizeof(*stas_entry), GFP_ATOMIC);
+	if (!stas_entry)
+		return;
+
+	stas_entry->sta = sta;
+	list_add_tail(&stas_entry->list, &iter_stas->list);
+}
+
+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;
+
+	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);
+	}
+}
+
+struct rtw_vifs_entry {
+	struct list_head list;
+	struct ieee80211_vif *vif;
+	u8 mac[ETH_ALEN];
+};
+
+struct rtw_iter_vifs_data {
+	struct rtw_dev *rtwdev;
+	struct list_head list;
+};
+
+void rtw_collect_vif_iter(void *data, u8 *mac, struct ieee80211_vif *vif)
+{
+	struct rtw_iter_vifs_data *iter_stas = (struct rtw_iter_vifs_data *)data;
+	struct rtw_vifs_entry *vifs_entry;
+
+	vifs_entry = kmalloc(sizeof(*vifs_entry), GFP_ATOMIC);
+	if (!vifs_entry)
+		return;
+
+	vifs_entry->vif = vif;
+	ether_addr_copy(vifs_entry->mac, mac);
+	list_add_tail(&vifs_entry->list, &iter_stas->list);
+}
+
+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;
+
+	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);
+	}
+}
diff --git a/util.h b/util.h
index 06a5b4c4..e4995dba 100644
--- a/util.h
+++ b/util.h
@@ -7,18 +7,21 @@
 
 struct rtw_dev;
 
-#define rtw_iterate_vifs(rtwdev, iterator, data)                               \
-	ieee80211_iterate_active_interfaces(rtwdev->hw,                        \
-			IEEE80211_IFACE_ITER_NORMAL, iterator, data)
 #define rtw_iterate_vifs_atomic(rtwdev, iterator, data)                        \
 	ieee80211_iterate_active_interfaces_atomic(rtwdev->hw,                 \
 			IEEE80211_IFACE_ITER_NORMAL, iterator, data)
-#define rtw_iterate_stas(rtwdev, iterator, data)                        \
-	ieee80211_iterate_stations(rtwdev->hw, iterator, data)
 #define rtw_iterate_stas_atomic(rtwdev, iterator, data)                        \
 	ieee80211_iterate_stations_atomic(rtwdev->hw, iterator, data)
 #define rtw_iterate_keys(rtwdev, vif, iterator, data)			       \
 	ieee80211_iter_keys(rtwdev->hw, vif, iterator, data)
+void rtw_iterate_vifs(struct rtw_dev *rtwdev,
+		      void (*iterator)(void *data, u8 *mac,
+				       struct ieee80211_vif *vif),
+		      void *data);
+void rtw_iterate_stas(struct rtw_dev *rtwdev,
+		      void (*iterator)(void *data,
+				       struct ieee80211_sta *sta),
+				       void *data);
 
 static inline u8 *get_hdr_bssid(struct ieee80211_hdr *hdr)
 {
-- 
2.25.1