ath10k: use locked skb_dequeue for rx completions

In our environment we are occasionally seeing the following stack trace
in ath10k:

Unable to handle kernel paging request at virtual address 0000a800
pgd = c0204000
[0000a800] *pgd=00000000
Internal error: Oops: 17 [#1] SMP ARM
Modules linked in: dwc3 dwc3_of_simple phy_qcom_dwc3 nf_nat xt_connmark
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.31 #2
Hardware name: Generic DT based system
task: c09f4f40 task.stack: c09ee000
PC is at kfree_skb_list+0x1c/0x2c
LR is at skb_release_data+0x6c/0x108
pc : [<c065dcc4>]    lr : [<c065da5c>]    psr: 200f0113
sp : c09efb68  ip : c09efb80  fp : c09efb7c
r10: 00000000  r9 : 00000000  r8 : 043fddd1
r7 : bf15d160  r6 : 00000000  r5 : d4ca2f00  r4 : ca7c6480
r3 : 000000a0  r2 : 01000000  r1 : c0a57470  r0 : 0000a800
Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 10c5787d  Table: 56e6006a  DAC: 00000051
Process swapper/0 (pid: 0, stack limit = 0xc09ee210)
Stack: (0xc09efb68 to 0xc09f0000)
fb60:                   ca7c6480 d4ca2f00 c09efb9c c09efb80 c065da5c c065dcb4
fb80: d4ca2f00 00000000 dcbf8400 bf15d160 c09efbb4 c09efba0 c065db28 c065d9fc
fba0: d4ca2f00 00000000 c09efbcc c09efbb8 c065db48 c065db04 d4ca2f00 00000000
fbc0: c09efbe4 c09efbd0 c065ddd0 c065db38 d4ca2f00 00000000 c09efc64 c09efbe8
fbe0: bf09bd00 c065dd10 00000003 7fffffff c09efc24 dcbfc9c0 01200000 00000000
fc00: 00000000 00000000 ddb7e440 c09e9440 c09efc48 1d195000 c09efc7c c09efc28
fc20: c027bb68 c028aa00 ddb7e4f8 bf13231c ddb7e454 0004091f bf154571 d4ca2f00
fc40: dcbf8d00 ca7c5df6 bf154538 01200000 00000000 bf154538 c09efd1c c09efc68
fc60: bf132458 bf09bbbc ca7c5dec 00000041 bf154538 bf154539 000007bf bf154545
fc80: bf154538 bf154538 bf154538 bf154538 bf154538 00000000 00000000 000016c1
fca0: 00000001 c09efcb0 01200000 00000000 00000000 00000000 00000000 00000001
fcc0: bf154539 00000041 00000000 00000007 00000000 000000d0 ffffffff 3160ffff
fce0: 9ad93e97 3e973160 7bf09ad9 0004091f d4ca2f00 c09efdb0 dcbf94e8 00000000
fd00: dcbf8d00 01200000 00000000 dcbf8d00 c09efd44 c09efd20 bf132544 bf132130
fd20: dcbf8d00 00000000 d4ca2f00 c09efdb0 00000001 d4ca2f00 c09efdec c09efd48
fd40: bf133630 bf1324d0 ca7c5cc0 000007c0 c09efd88 c09efd70 c0764230 c02277d8
fd60: 200f0113 ffffffff dcbf94c8 bf000000 dcbf93b0 dcbf8d00 00000040 dcbf945c
fd80: dcbf94e8 00000000 c09efdcc 00000000 c09efd90 c09efd90 00000000 00000024
fda0: dcbf8d00 00000000 00000005 dcbf8d00 c09efdb0 c09efdb0 00000000 00000040
fdc0: c09efdec dcbf8d00 dcbfc9c0 c09ed140 00000040 00000000 00000100 00000040
fde0: c09efe14 c09efdf0 bf1739b4 bf132840 dcbfc9c0 ddb82140 c09ed140 1d195000
fe00: 00000001 00000100 c09efe64 c09efe18 c067136c bf173958 ddb7fac8 c09f0d00
fe20: 001df678 0000012c c09efe28 c09efe28 c09efe30 c09efe30 c0a7fb28 ffffe000
fe40: c09f008c 00000003 00000008 c0a598c0 00000100 c09f0080 c09efeb4 c09efe68
fe60: c02096e0 c0671278 c0494584 00000080 dd5c3300 c09f0d00 00000004 001df677
fe80: 0000000a 00200100 dd5c3300 00000000 00000000 c09eaa70 00000060 dd410800
fea0: c09ee000 00000000 c09efecc c09efeb8 c0227944 c02094c4 00000000 00000000
fec0: c09efef4 c09efed0 c0268b64 c02278ac de802000 c09f1b1c c09eff20 c0a16cc0
fee0: de803000 c09ee000 c09eff1c c09efef8 c020947c c0268ae0 c02103dc 600f0013
ff00: ffffffff c09eff54 ffffe000 c09ee000 c09eff7c c09eff20 c021448c c0209424
ff20: 00000001 00000000 00000000 c021ddc0 00000000 00000000 c09f1024 00000001
ff40: ffffe000 c09f1078 00000000 c09eff7c c09eff80 c09eff70 c02103ec c02103dc
ff60: 600f0013 ffffffff 00000051 00000000 c09eff8c c09eff80 c0763cc4 c02103bc
ff80: c09effa4 c09eff90 c025f0e4 c0763c98 c0a59040 c09f1000 c09effb4 c09effa8
ffa0: c075efe0 c025efd4 c09efff4 c09effb8 c097dcac c075ef7c ffffffff ffffffff
ffc0: 00000000 c097d6c4 00000000 c09c1a28 c0a59294 c09f101c c09c1a24 c09f61c0
ffe0: 4220406a 512f04d0 00000000 c09efff8 4220807c c097d95c 00000000 00000000
[<c065dcc4>] (kfree_skb_list) from [<c065da5c>] (skb_release_data+0x6c/0x108)
[<c065da5c>] (skb_release_data) from [<c065db28>] (skb_release_all+0x30/0x34)
[<c065db28>] (skb_release_all) from [<c065db48>] (__kfree_skb+0x1c/0x9c)
[<c065db48>] (__kfree_skb) from [<c065ddd0>] (consume_skb+0xcc/0xd8)
[<c065ddd0>] (consume_skb) from [<bf09bd00>] (ieee80211_rx_napi+0x150/0x82c [mac80211])
[<bf09bd00>] (ieee80211_rx_napi [mac80211]) from [<bf132458>] (ath10k_htt_t2h_msg_handler+0x15e8/0x19c4 [ath10k_core])
[<bf132458>] (ath10k_htt_t2h_msg_handler [ath10k_core]) from [<bf132544>] (ath10k_htt_t2h_msg_handler+0x16d4/0x19c4 [ath10k_core])
[<bf132544>] (ath10k_htt_t2h_msg_handler [ath10k_core]) from [<bf133630>] (ath10k_htt_txrx_compl_task+0xdfc/0x12cc [ath10k_core])
[<bf133630>] (ath10k_htt_txrx_compl_task [ath10k_core]) from [<bf1739b4>] (ath10k_pci_napi_poll+0x68/0xf4 [ath10k_pci])
[<bf1739b4>] (ath10k_pci_napi_poll [ath10k_pci]) from [<c067136c>] (net_rx_action+0x100/0x33c)
[<c067136c>] (net_rx_action) from [<c02096e0>] (__do_softirq+0x228/0x31c)
[<c02096e0>] (__do_softirq) from [<c0227944>] (irq_exit+0xa4/0x114)

The trace points to a corrupt skb inside kfree_skb(), seemingly because
one of the shared skb queues is getting corrupted.  Most of the skb queues
ath10k uses are local to a single call stack, but three are shared among
multiple codepaths:

 - rx_msdus_q,
 - rx_in_ord_compl_q, and
 - tx_fetch_ind_q

Of the three, the first two are manipulated using the unlocked skb_queue
functions without any additional lock protecting them.  Use the locked
variants of skb_queue_* functions to protect these manipulations.
Signed-off-by: Bob Copeland <bobcopeland@fb.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath10k/htt_rx.c

@@ -1092,7 +1092,7 @@ static void ath10k_htt_rx_h_queue_msdu(struct ath10k *ar,
 	status = IEEE80211_SKB_RXCB(skb);
 	*status = *rx_status;
 
-	__skb_queue_tail(&ar->htt.rx_msdus_q, skb);
+	skb_queue_tail(&ar->htt.rx_msdus_q, skb);
 }
 
 static void ath10k_process_rx(struct ath10k *ar, struct sk_buff *skb)
@@ -2813,7 +2813,7 @@ bool ath10k_htt_t2h_msg_handler(struct ath10k *ar, struct sk_buff *skb)
 		break;
 	}
 	case HTT_T2H_MSG_TYPE_RX_IN_ORD_PADDR_IND: {
-		__skb_queue_tail(&htt->rx_in_ord_compl_q, skb);
+		skb_queue_tail(&htt->rx_in_ord_compl_q, skb);
 		return false;
 	}
 	case HTT_T2H_MSG_TYPE_TX_CREDIT_UPDATE_IND:
@@ -2877,7 +2877,7 @@ static int ath10k_htt_rx_deliver_msdu(struct ath10k *ar, int quota, int budget)
 		if (skb_queue_empty(&ar->htt.rx_msdus_q))
 			break;
 
-		skb = __skb_dequeue(&ar->htt.rx_msdus_q);
+		skb = skb_dequeue(&ar->htt.rx_msdus_q);
 		if (!skb)
 			break;
 		ath10k_process_rx(ar, skb);
@@ -2908,7 +2908,7 @@ int ath10k_htt_txrx_compl_task(struct ath10k *ar, int budget)
 		goto exit;
 	}
 
-	while ((skb = __skb_dequeue(&htt->rx_in_ord_compl_q))) {
+	while ((skb = skb_dequeue(&htt->rx_in_ord_compl_q))) {
 		spin_lock_bh(&htt->rx_ring.lock);
 		ret = ath10k_htt_rx_in_ord_ind(ar, skb);
 		spin_unlock_bh(&htt->rx_ring.lock);