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Message-ID: <833facaa-6b8d-4301-84e1-bef1980f26b6@quicinc.com>
Date: Wed, 24 Apr 2024 13:41:25 -0700
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Subject: Re: [PATCH v2 3/3] wifi: ath12k: Add lock to protect the hardware
 state
Content-Language: en-US
To: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>,
        <ath12k@lists.infradead.org>
CC: <linux-wireless@vger.kernel.org>
References: <20240424065646.1666166-1-quic_periyasa@quicinc.com>
 <20240424065646.1666166-4-quic_periyasa@quicinc.com>
From: Jeff Johnson <quic_jjohnson@quicinc.com>
In-Reply-To: <20240424065646.1666166-4-quic_periyasa@quicinc.com>
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On 4/23/2024 11:56 PM, Karthikeyan Periyasamy wrote:
> Currently, hardware state is not protected across the reconfigure
> operations. However, in single wiphy models, multiple radio/links is
> exposed as a MAC hardware (ieee80211_hw) through the driver hardware
> abstraction (ath12k_hw) layer. In such scenario, we need to protect
> hardware state across the multiple radio/link at the driver hardware
> abstraction (ath12k_hw) layer. Therefore, introduce a new mutex in
> the ath12k_hw layer.
> 
> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1
> 
> Signed-off-by: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
> ---
>  drivers/net/wireless/ath/ath12k/core.c |  4 ++++
>  drivers/net/wireless/ath/ath12k/core.h |  6 ++++++
>  drivers/net/wireless/ath/ath12k/mac.c  | 29 ++++++++++++++++++++++++--
>  3 files changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath12k/core.c b/drivers/net/wireless/ath/ath12k/core.c
> index a685cfd6fd92..e9aabdb9341c 100644
> --- a/drivers/net/wireless/ath/ath12k/core.c
> +++ b/drivers/net/wireless/ath/ath12k/core.c
> @@ -1048,6 +1048,8 @@ static void ath12k_core_post_reconfigure_recovery(struct ath12k_base *ab)
>  		if (!ah || ah->state == ATH12K_HW_STATE_OFF)
>  			continue;
>  
> +		mutex_lock(&ah->hw_mutex);
> +
>  		switch (ah->state) {
>  		case ATH12K_HW_STATE_ON:
>  			ah->state = ATH12K_HW_STATE_RESTARTING;
> @@ -1078,6 +1080,8 @@ static void ath12k_core_post_reconfigure_recovery(struct ath12k_base *ab)
>  				    "device is wedged, will not restart hw %d\n", i);
>  			break;
>  		}
> +
> +		mutex_unlock(&ah->hw_mutex);
>  	}
>  
>  	complete(&ab->driver_recovery);
> diff --git a/drivers/net/wireless/ath/ath12k/core.h b/drivers/net/wireless/ath/ath12k/core.h
> index eff1093fbb6e..3e3e157b6c56 100644
> --- a/drivers/net/wireless/ath/ath12k/core.h
> +++ b/drivers/net/wireless/ath/ath12k/core.h
> @@ -634,11 +634,17 @@ struct ath12k {
>  struct ath12k_hw {
>  	struct ieee80211_hw *hw;
>  	struct ath12k_base *ab;
> +
> +	/* Protect the write operation of the hardware state ath12k_hw::state
> +	 * between hardware start<=>reconfigure<=>stop transitions.
> +	 */
> +	struct mutex hw_mutex;
>  	enum ath12k_hw_state state;
>  	bool regd_updated;
>  	bool use_6ghz_regd;
>  	u8 num_radio;
>  
> +	/* Keep last */
>  	struct ath12k radio[] __aligned(sizeof(void *));
>  };
>  
> diff --git a/drivers/net/wireless/ath/ath12k/mac.c b/drivers/net/wireless/ath/ath12k/mac.c
> index 8b003c18796d..3dc95d36b6a2 100644
> --- a/drivers/net/wireless/ath/ath12k/mac.c
> +++ b/drivers/net/wireless/ath/ath12k/mac.c
> @@ -5546,10 +5546,13 @@ static void ath12k_mac_wait_reconfigure(struct ath12k_base *ab)
>  
>  static int ath12k_mac_start(struct ath12k *ar)
>  {
> +	struct ath12k_hw *ah = ar->ah;
>  	struct ath12k_base *ab = ar->ab;
>  	struct ath12k_pdev *pdev = ar->pdev;
>  	int ret;
>  
> +	lockdep_assert_held(&ah->hw_mutex);
> +
>  	mutex_lock(&ar->conf_mutex);
>  
>  	ret = ath12k_wmi_pdev_set_param(ar, WMI_PDEV_PARAM_PMF_QOS,
> @@ -5664,6 +5667,8 @@ static int ath12k_mac_op_start(struct ieee80211_hw *hw)
>  
>  	ath12k_drain_tx(ah);
>  
> +	mutex_lock(&ah->hw_mutex);

since this is always unlocked just before we return, it is a good candidate
for the cleanup.h functionality. just change this to:
	guard(mutex)(&ah->hw_mutex);

and remove all of the other edits to this function. the mutex will always be
unlocked when the function returns

> +
>  	switch (ah->state) {
>  	case ATH12K_HW_STATE_OFF:
>  		ah->state = ATH12K_HW_STATE_ON;
> @@ -5678,7 +5683,8 @@ static int ath12k_mac_op_start(struct ieee80211_hw *hw)
>  		ah->state = ATH12K_HW_STATE_OFF;
>  
>  		WARN_ON(1);
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto err;
>  	}
>  
>  	for_each_ar(ah, ar, i) {
> @@ -5692,6 +5698,8 @@ static int ath12k_mac_op_start(struct ieee80211_hw *hw)
>  		}
>  	}
>  
> +	mutex_unlock(&ah->hw_mutex);
> +
>  	return 0;
>  
>  fail_start:
> @@ -5700,6 +5708,8 @@ static int ath12k_mac_op_start(struct ieee80211_hw *hw)
>  		ath12k_mac_stop(ar);
>  	}
>  
> +err:
> +	mutex_unlock(&ah->hw_mutex);
>  	return ret;
>  }
>  
> @@ -5762,9 +5772,12 @@ int ath12k_mac_rfkill_enable_radio(struct ath12k *ar, bool enable)
>  
>  static void ath12k_mac_stop(struct ath12k *ar)
>  {
> +	struct ath12k_hw *ah = ar->ah;
>  	struct htt_ppdu_stats_info *ppdu_stats, *tmp;
>  	int ret;
>  
> +	lockdep_assert_held(&ah->hw_mutex);
> +
>  	mutex_lock(&ar->conf_mutex);
>  	ret = ath12k_mac_config_mon_status_default(ar, false);
>  	if (ret && (ret != -EOPNOTSUPP))
> @@ -5800,10 +5813,14 @@ static void ath12k_mac_op_stop(struct ieee80211_hw *hw)
>  
>  	ath12k_drain_tx(ah);
>  
> +	mutex_lock(&ah->hw_mutex);
> +
>  	ah->state = ATH12K_HW_STATE_OFF;
>  
>  	for_each_ar(ah, ar, i)
>  		ath12k_mac_stop(ar);
> +
> +	mutex_unlock(&ah->hw_mutex);
>  }
>  
>  static u8
> @@ -7848,8 +7865,12 @@ ath12k_mac_op_reconfig_complete(struct ieee80211_hw *hw,
>  	if (reconfig_type != IEEE80211_RECONFIG_TYPE_RESTART)
>  		return;
>  
> -	if (ah->state != ATH12K_HW_STATE_RESTARTED)
> +	mutex_lock(&ah->hw_mutex);

another good candidate for
	guard(mutex)(&ah->hw_mutex);

> +
> +	if (ah->state != ATH12K_HW_STATE_RESTARTED) {
> +		mutex_unlock(&ah->hw_mutex);
>  		return;
> +	}
>  
>  	ah->state = ATH12K_HW_STATE_ON;
>  	ieee80211_wake_queues(hw);
> @@ -7904,6 +7925,8 @@ ath12k_mac_op_reconfig_complete(struct ieee80211_hw *hw,
>  
>  		mutex_unlock(&ar->conf_mutex);
>  	}
> +
> +	mutex_unlock(&ah->hw_mutex);
>  }
>  
>  static void
> @@ -8850,6 +8873,8 @@ static struct ath12k_hw *ath12k_mac_hw_allocate(struct ath12k_base *ab,
>  	ah->ab = ab;
>  	ah->num_radio = num_pdev_map;
>  
> +	mutex_init(&ah->hw_mutex);
> +
>  	for (i = 0; i < num_pdev_map; i++) {
>  		ab = pdev_map[i].ab;
>  		pdev_idx = pdev_map[i].pdev_idx;