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From: Kang Yang <quic_kangyang@quicinc.com>
To: <ath12k@lists.infradead.org>
CC: <linux-wireless@vger.kernel.org>, <quic_kangyang@quicinc.com>
Subject: [PATCH] wifi: ath12k: add rcu lock for ath12k_wmi_p2p_noa_event()
Date: Fri, 23 Feb 2024 13:45:05 +0800
Message-ID: <20240223054505.438839-1-quic_kangyang@quicinc.com>
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Warning will appear when running P2P GO:

WARNING: suspicious RCU usage
drivers/net/wireless/ath/ath12k/mac.c:583 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
no locks held by swapper/0/0.
stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.8.0-rc4-wt-ath+ #4
Call Trace:
 <IRQ>
 dump_stack_lvl+0x82/0xa0
 dump_stack+0x14/0x20
 lockdep_rcu_suspicious+0x214/0x3b0
 ath12k_mac_get_ar_by_vdev_id+0x192/0x220 [ath12k]
 ath12k_wmi_op_rx+0x2d7/0x1b40 [ath12k]

ath12k_mac_get_ar_by_vdev_id() requires its callers to have called
rcu_read_lock(), but in ath12k_wmi_p2p_noa_event() it is called without
doing so, and hence the warning was triggered.

Add rcu_read_lock() and rcu_read_unlock() to avoid warning.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Fixes: 9411eecb60cb ("wifi: ath12k: implement handling of P2P NoA event")
Reported-by: Kalle Valo <quic_kvalo@quicinc.com>
Closes: https://lore.kernel.org/linux-wireless/87o7cusyvw.fsf@kernel.org/
Signed-off-by: Kang Yang <quic_kangyang@quicinc.com>
---
 drivers/net/wireless/ath/ath12k/wmi.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath12k/wmi.c b/drivers/net/wireless/ath/ath12k/wmi.c
index 838161dd9098..9d69a1769926 100644
--- a/drivers/net/wireless/ath/ath12k/wmi.c
+++ b/drivers/net/wireless/ath/ath12k/wmi.c
@@ -6736,18 +6736,21 @@ static int ath12k_wmi_p2p_noa_event(struct ath12k_base *ab,
 		   "wmi tlv p2p noa vdev_id %i descriptors %u\n",
 		   vdev_id, le32_get_bits(noa->noa_attr, WMI_P2P_NOA_INFO_DESC_NUM));
 
+	rcu_read_lock();
 	ar = ath12k_mac_get_ar_by_vdev_id(ab, vdev_id);
 	if (!ar) {
 		ath12k_warn(ab, "invalid vdev id %d in P2P NoA event\n",
 			    vdev_id);
 		ret = -EINVAL;
-		goto out;
+		goto unlock;
 	}
 
 	ath12k_p2p_noa_update_by_vdev_id(ar, vdev_id, noa);
 
 	ret = 0;
 
+unlock:
+	rcu_read_unlock();
 out:
 	kfree(tb);
 	return ret;

base-commit: 707e306f3573fa321ae197d77366578e4566cff5
-- 
2.34.1