staging: rtl8723bs: Fix access-point mode deadlock

Commit 54659ca026e5 ("staging: rtl8723bs: remove possible deadlock when
disconnect (v2)") split the locking of pxmitpriv->lock vs sleep_q/lock
into 2 locks in attempt to fix a lockdep reported issue with the locking
order of the sta_hash_lock vs pxmitpriv->lock.

But in the end this turned out to not fully solve the sta_hash_lock issue
so commit a7ac783c338b ("staging: rtl8723bs: remove a second possible
deadlock") was added to fix this in another way.

The original fix was kept as it was still seen as a good thing to have,
but now it turns out that it creates a deadlock in access-point mode:

[Feb20 23:47] ======================================================
[  +0.074085] WARNING: possible circular locking dependency detected
[  +0.074077] 5.16.0-1-amd64 #1 Tainted: G         C  E
[  +0.064710] ------------------------------------------------------
[  +0.074075] ksoftirqd/3/29 is trying to acquire lock:
[  +0.060542] ffffb8b30062ab00 (&pxmitpriv->lock){+.-.}-{2:2}, at: rtw_xmit_classifier+0x8a/0x140 [r8723bs]
[  +0.114921]
              but task is already holding lock:
[  +0.069908] ffffb8b3007ab704 (&psta->sleep_q.lock){+.-.}-{2:2}, at: wakeup_sta_to_xmit+0x3b/0x300 [r8723bs]
[  +0.116976]
              which lock already depends on the new lock.

[  +0.098037]
              the existing dependency chain (in reverse order) is:
[  +0.089704]
              -> #1 (&psta->sleep_q.lock){+.-.}-{2:2}:
[  +0.077232]        _raw_spin_lock_bh+0x34/0x40
[  +0.053261]        xmitframe_enqueue_for_sleeping_sta+0xc1/0x2f0 [r8723bs]
[  +0.082572]        rtw_xmit+0x58b/0x940 [r8723bs]
[  +0.056528]        _rtw_xmit_entry+0xba/0x350 [r8723bs]
[  +0.062755]        dev_hard_start_xmit+0xf1/0x320
[  +0.056381]        sch_direct_xmit+0x9e/0x360
[  +0.052212]        __dev_queue_xmit+0xce4/0x1080
[  +0.055334]        ip6_finish_output2+0x18f/0x6e0
[  +0.056378]        ndisc_send_skb+0x2c8/0x870
[  +0.052209]        ndisc_send_ns+0xd3/0x210
[  +0.050130]        addrconf_dad_work+0x3df/0x5a0
[  +0.055338]        process_one_work+0x274/0x5a0
[  +0.054296]        worker_thread+0x52/0x3b0
[  +0.050124]        kthread+0x16c/0x1a0
[  +0.044925]        ret_from_fork+0x1f/0x30
[  +0.049092]
              -> #0 (&pxmitpriv->lock){+.-.}-{2:2}:
[  +0.074101]        __lock_acquire+0x10f5/0x1d80
[  +0.054298]        lock_acquire+0xd7/0x300
[  +0.049088]        _raw_spin_lock_bh+0x34/0x40
[  +0.053248]        rtw_xmit_classifier+0x8a/0x140 [r8723bs]
[  +0.066949]        rtw_xmitframe_enqueue+0xa/0x20 [r8723bs]
[  +0.066946]        rtl8723bs_hal_xmitframe_enqueue+0x14/0x50 [r8723bs]
[  +0.078386]        wakeup_sta_to_xmit+0xa6/0x300 [r8723bs]
[  +0.065903]        rtw_recv_entry+0xe36/0x1160 [r8723bs]
[  +0.063809]        rtl8723bs_recv_tasklet+0x349/0x6c0 [r8723bs]
[  +0.071093]        tasklet_action_common.constprop.0+0xe5/0x110
[  +0.070966]        __do_softirq+0x16f/0x50a
[  +0.050134]        __irq_exit_rcu+0xeb/0x140
[  +0.051172]        irq_exit_rcu+0xa/0x20
[  +0.047006]        common_interrupt+0xb8/0xd0
[  +0.052214]        asm_common_interrupt+0x1e/0x40
[  +0.056381]        finish_task_switch.isra.0+0x100/0x3a0
[  +0.063670]        __schedule+0x3ad/0xd20
[  +0.048047]        schedule+0x4e/0xc0
[  +0.043880]        smpboot_thread_fn+0xc4/0x220
[  +0.054298]        kthread+0x16c/0x1a0
[  +0.044922]        ret_from_fork+0x1f/0x30
[  +0.049088]
              other info that might help us debug this:

[  +0.095950]  Possible unsafe locking scenario:

[  +0.070952]        CPU0                    CPU1
[  +0.054282]        ----                    ----
[  +0.054285]   lock(&psta->sleep_q.lock);
[  +0.047004]                                lock(&pxmitpriv->lock);
[  +0.074082]                                lock(&psta->sleep_q.lock);
[  +0.077209]   lock(&pxmitpriv->lock);
[  +0.043873]
               *** DEADLOCK ***

[  +0.070950] 1 lock held by ksoftirqd/3/29:
[  +0.049082]  #0: ffffb8b3007ab704 (&psta->sleep_q.lock){+.-.}-{2:2}, at: wakeup_sta_to_xmit+0x3b/0x300 [r8723bs]

Analysis shows that in hindsight the splitting of the lock was not
a good idea, so revert this to fix the access-point mode deadlock.

Note this is a straight-forward revert done with git revert, the commented
out "/* spin_lock_bh(&psta_bmc->sleep_q.lock); */" lines were part of the
code before the reverted changes.

Fixes: 54659ca026e5 ("staging: rtl8723bs: remove possible deadlock when disconnect (v2)")
Cc: stable <stable@vger.kernel.org>
Cc: Fabio Aiuto <fabioaiuto83@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215542
Link: https://lore.kernel.org/r/20220302101637.26542-1-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 7 deletions

diff --git a/drivers/staging/rtl8723bs/core/rtw_xmit.c b/drivers/staging/rtl8723bs/core/rtw_xmit.c
index 13b8bd5ffabc..f466bfd248fb 100644
--- a/drivers/staging/rtl8723bs/core/rtw_xmit.c
+++ b/drivers/staging/rtl8723bs/core/rtw_xmit.c
@@ -1734,12 +1734,15 @@ void rtw_free_xmitframe_queue(struct xmit_priv *pxmitpriv, struct __queue *pfram
 	struct list_head *plist, *phead, *tmp;
 	struct	xmit_frame	*pxmitframe;
 
+	spin_lock_bh(&pframequeue->lock);
+
 	phead = get_list_head(pframequeue);
 	list_for_each_safe(plist, tmp, phead) {
 		pxmitframe = list_entry(plist, struct xmit_frame, list);
 
 		rtw_free_xmitframe(pxmitpriv, pxmitframe);
 	}
+	spin_unlock_bh(&pframequeue->lock);
 }
 
 s32 rtw_xmitframe_enqueue(struct adapter *padapter, struct xmit_frame *pxmitframe)
@@ -1794,7 +1797,6 @@ s32 rtw_xmit_classifier(struct adapter *padapter, struct xmit_frame *pxmitframe)
 	struct sta_info *psta;
 	struct tx_servq	*ptxservq;
 	struct pkt_attrib	*pattrib = &pxmitframe->attrib;
-	struct xmit_priv *xmit_priv = &padapter->xmitpriv;
 	struct hw_xmit	*phwxmits =  padapter->xmitpriv.hwxmits;
 	signed int res = _SUCCESS;
 
@@ -1812,14 +1814,12 @@ s32 rtw_xmit_classifier(struct adapter *padapter, struct xmit_frame *pxmitframe)
 
 	ptxservq = rtw_get_sta_pending(padapter, psta, pattrib->priority, (u8 *)(&ac_index));
 
-	spin_lock_bh(&xmit_priv->lock);
 	if (list_empty(&ptxservq->tx_pending))
 		list_add_tail(&ptxservq->tx_pending, get_list_head(phwxmits[ac_index].sta_queue));
 
 	list_add_tail(&pxmitframe->list, get_list_head(&ptxservq->sta_pending));
 	ptxservq->qcnt++;
 	phwxmits[ac_index].accnt++;
-	spin_unlock_bh(&xmit_priv->lock);
 
 exit:
 
@@ -2202,10 +2202,11 @@ void wakeup_sta_to_xmit(struct adapter *padapter, struct sta_info *psta)
 	struct list_head *xmitframe_plist, *xmitframe_phead, *tmp;
 	struct xmit_frame *pxmitframe = NULL;
 	struct sta_priv *pstapriv = &padapter->stapriv;
+	struct xmit_priv *pxmitpriv = &padapter->xmitpriv;
 
 	psta_bmc = rtw_get_bcmc_stainfo(padapter);
 
-	spin_lock_bh(&psta->sleep_q.lock);
+	spin_lock_bh(&pxmitpriv->lock);
 
 	xmitframe_phead = get_list_head(&psta->sleep_q);
 	list_for_each_safe(xmitframe_plist, tmp, xmitframe_phead) {
@@ -2306,7 +2307,7 @@ void wakeup_sta_to_xmit(struct adapter *padapter, struct sta_info *psta)
 
 _exit:
 
-	spin_unlock_bh(&psta->sleep_q.lock);
+	spin_unlock_bh(&pxmitpriv->lock);
 
 	if (update_mask)
 		update_beacon(padapter, WLAN_EID_TIM, NULL, true);
@@ -2318,8 +2319,9 @@ void xmit_delivery_enabled_frames(struct adapter *padapter, struct sta_info *pst
 	struct list_head *xmitframe_plist, *xmitframe_phead, *tmp;
 	struct xmit_frame *pxmitframe = NULL;
 	struct sta_priv *pstapriv = &padapter->stapriv;
+	struct xmit_priv *pxmitpriv = &padapter->xmitpriv;
 
-	spin_lock_bh(&psta->sleep_q.lock);
+	spin_lock_bh(&pxmitpriv->lock);
 
 	xmitframe_phead = get_list_head(&psta->sleep_q);
 	list_for_each_safe(xmitframe_plist, tmp, xmitframe_phead) {
@@ -2372,7 +2374,7 @@ void xmit_delivery_enabled_frames(struct adapter *padapter, struct sta_info *pst
 		}
 	}
 
-	spin_unlock_bh(&psta->sleep_q.lock);
+	spin_unlock_bh(&pxmitpriv->lock);
 }
 
 void enqueue_pending_xmitbuf(struct xmit_priv *pxmitpriv, struct xmit_buf *pxmitbuf)