[PATCH 0/2] Improve ath10k flush queue mechanism

[PATCH 0/2] Improve ath10k flush queue mechanism

[Remi Pommarel]

It has been reported [0] that a 3-4 seconds (actually up to 5 sec) of
radio silence could be observed followed by the error below on ath10k
devices:

 ath10k_pci 0000:04:00.0: failed to flush transmit queue (skip 0 ar-state 1): 0

This is due to how the TX queues are flushed in ath10k. When a STA is
removed, mac80211 need to flush queues [1], but because ath10k does not
have a lightweight .flush_sta operation, ieee80211_flush_queues() is
called instead effectively blocking the whole queue during the drain
causing this radio silence. Also because ath10k_flush() waits for all
queued to be emptied, not only the flushed ones it could more easily
take up to 5 seconds to finish making the whole situation worst.

The first patch of this series adds a .flush_sta operation to flush only
specific STA traffic avoiding the need to stop whole queues and should
be enough in itself to fix the reported issue.

The second patch of this series is a proposal to improve ath10k_flush so
that it will be less likely to timeout waiting for non related queues to
drain.

The abose kernel warning could still be observed (e.g. flushing a dead
STA) but should be now harmless.

[0]: https://lore.kernel.org/all/CA+Xfe4FjUmzM5mvPxGbpJsF3SvSdE5_wgxvgFJ0bsdrKODVXCQ@mail.gmail.com/
[1]: commit 0b75a1b1e42e ("wifi: mac80211: flush queues on STA removal")

Remi Pommarel (2):
  wifi: ath10k: Implement ieee80211 flush_sta callback
  wifi: ath10k: Flush only requested txq in ath10k_flush()

 drivers/net/wireless/ath/ath10k/core.h   |  4 ++
 drivers/net/wireless/ath/ath10k/htt.h    | 11 +++-
 drivers/net/wireless/ath/ath10k/htt_tx.c | 50 +++++++++++++++-
 drivers/net/wireless/ath/ath10k/mac.c    | 76 ++++++++++++++++++++----
 drivers/net/wireless/ath/ath10k/txrx.c   |  5 +-
 5 files changed, 129 insertions(+), 17 deletions(-)

-- 
2.40.0

[PATCH 1/2] wifi: ath10k: Implement ieee80211 flush_sta callback

[Remi Pommarel]

When a STA reassociates, mac80211's _sta_info_move_state() waits for all
pending frame to be flushed before removing the key (so that no frame
get sent unencrypted after key removable [0]). When a driver does not
implement the flush_sta callback, ieee80211_flush_queues() is called
instead which effectively stops the whole queue until it is completely
drained.

The ath10k driver configure all STAs of one vdev to share the same
queue. So when flushing one STA this is the whole vdev queue that is
blocked until completely drained causing Tx to other STA to also stall
this whole time.

One easy way to reproduce the issue is to connect two STAs (STA0 and
STA1) to an ath10k AP. While Generating a bunch of traffic from AP to
STA0 (e.g. fping -l -p 20 <STA0-IP>) disconnect STA0 from AP without
clean disassociation (e.g. remove power, reboot -f). Then as soon as
STA0 is effectively disconnected from AP (either after inactivity
timeout or forced with iw dev AP station del STA0), its queues get
flushed using ieee80211_flush_queues(). This causes STA1 to suffer a
connectivity stall for about 5 seconds (see ATH10K_FLUSH_TIMEOUT_HZ).

Implement a flush_sta callback in ath10k to wait only for a specific
STA pending frames to be drained (without stopping the whole HW queue)
to fix that.

[0]: commit 0b75a1b1e42e ("wifi: mac80211: flush queues on STA removal")

Reported-by: Cedric Veilleux <veilleux.cedric@gmail.com>
Signed-off-by: Remi Pommarel <repk@triplefau.lt>
---
 drivers/net/wireless/ath/ath10k/core.h   |  4 +++
 drivers/net/wireless/ath/ath10k/htt.h    |  4 +++
 drivers/net/wireless/ath/ath10k/htt_tx.c | 32 ++++++++++++++++++
 drivers/net/wireless/ath/ath10k/mac.c    | 43 +++++++++++++++++++++++-
 drivers/net/wireless/ath/ath10k/txrx.c   |  3 ++
 5 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
index 446dca74f06a..4709e4887efc 100644
--- a/drivers/net/wireless/ath/ath10k/core.h
+++ b/drivers/net/wireless/ath/ath10k/core.h
@@ -558,6 +558,10 @@ struct ath10k_sta {
 	u8 rate_ctrl[ATH10K_TID_MAX];
 	u32 rate_code[ATH10K_TID_MAX];
 	int rtscts[ATH10K_TID_MAX];
+	/* protects num_fw_queued */
+	spinlock_t sta_tx_lock;
+	wait_queue_head_t empty_tx_wq;
+	unsigned int num_fw_queued;
 };
 
 #define ATH10K_VDEV_SETUP_TIMEOUT_HZ	(5 * HZ)
diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
index 603f6de62b0a..d150f9330941 100644
--- a/drivers/net/wireless/ath/ath10k/htt.h
+++ b/drivers/net/wireless/ath/ath10k/htt.h
@@ -2452,6 +2452,10 @@ int ath10k_htt_tx_inc_pending(struct ath10k_htt *htt);
 void ath10k_htt_tx_mgmt_dec_pending(struct ath10k_htt *htt);
 int ath10k_htt_tx_mgmt_inc_pending(struct ath10k_htt *htt, bool is_mgmt,
 				   bool is_presp);
+void ath10k_htt_tx_sta_inc_pending(struct ath10k_htt *htt,
+				   struct ieee80211_sta *sta);
+void ath10k_htt_tx_sta_dec_pending(struct ath10k_htt *htt,
+				   struct ieee80211_sta *sta);
 
 int ath10k_htt_tx_alloc_msdu_id(struct ath10k_htt *htt, struct sk_buff *skb);
 void ath10k_htt_tx_free_msdu_id(struct ath10k_htt *htt, u16 msdu_id);
diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
index 9725feecefd6..7477cb8f5d10 100644
--- a/drivers/net/wireless/ath/ath10k/htt_tx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
@@ -195,6 +195,38 @@ void ath10k_htt_tx_mgmt_dec_pending(struct ath10k_htt *htt)
 	htt->num_pending_mgmt_tx--;
 }
 
+void ath10k_htt_tx_sta_inc_pending(struct ath10k_htt *htt,
+				   struct ieee80211_sta *sta)
+{
+	struct ath10k_sta *arsta;
+
+	if (!sta)
+		return;
+
+	arsta = (struct ath10k_sta *)sta->drv_priv;
+
+	spin_lock_bh(&arsta->sta_tx_lock);
+	arsta->num_fw_queued++;
+	spin_unlock_bh(&arsta->sta_tx_lock);
+}
+
+void ath10k_htt_tx_sta_dec_pending(struct ath10k_htt *htt,
+				   struct ieee80211_sta *sta)
+{
+	struct ath10k_sta *arsta;
+
+	if (!sta)
+		return;
+
+	arsta = (struct ath10k_sta *)sta->drv_priv;
+
+	spin_lock_bh(&arsta->sta_tx_lock);
+	arsta->num_fw_queued--;
+	if (arsta->num_fw_queued == 0)
+		wake_up(&arsta->empty_tx_wq);
+	spin_unlock_bh(&arsta->sta_tx_lock);
+}
+
 int ath10k_htt_tx_alloc_msdu_id(struct ath10k_htt *htt, struct sk_buff *skb)
 {
 	struct ath10k *ar = htt->ar;
diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
index 646e1737d4c4..373a0aa6b01c 100644
--- a/drivers/net/wireless/ath/ath10k/mac.c
+++ b/drivers/net/wireless/ath/ath10k/mac.c
@@ -4423,6 +4423,8 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
 		spin_unlock_bh(&ar->htt.tx_lock);
 	}
 
+	ath10k_htt_tx_sta_inc_pending(&ar->htt, sta);
+
 	ret = ath10k_mac_tx(ar, vif, txmode, txpath, skb, false);
 	if (unlikely(ret)) {
 		ath10k_warn(ar, "failed to push frame: %d\n", ret);
@@ -4432,6 +4434,7 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
 		if (is_mgmt)
 			ath10k_htt_tx_mgmt_dec_pending(htt);
 		spin_unlock_bh(&ar->htt.tx_lock);
+		ath10k_htt_tx_sta_dec_pending(&ar->htt, sta);
 
 		return ret;
 	}
@@ -7474,7 +7477,8 @@ static int ath10k_sta_state(struct ieee80211_hw *hw,
 		arsta->peer_ps_state = WMI_PEER_PS_STATE_DISABLED;
 		INIT_WORK(&arsta->update_wk, ath10k_sta_rc_update_wk);
 		INIT_WORK(&arsta->tid_config_wk, ath10k_sta_tid_cfg_wk);
-
+		spin_lock_init(&arsta->sta_tx_lock);
+		init_waitqueue_head(&arsta->empty_tx_wq);
 		for (i = 0; i < ARRAY_SIZE(sta->txq); i++)
 			ath10k_mac_txq_init(sta->txq[i]);
 	}
@@ -8098,6 +8102,42 @@ static void ath10k_flush(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	mutex_unlock(&ar->conf_mutex);
 }
 
+static void ath10k_flush_sta(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
+			     struct ieee80211_sta *sta)
+{
+	struct ath10k_sta *arsta = (struct ath10k_sta *)sta->drv_priv;
+	struct ath10k *ar = hw->priv;
+	bool skip;
+	long time_left;
+
+	/* TODO do we need drop implemented here ? */
+
+	mutex_lock(&ar->conf_mutex);
+
+	if (ar->state == ATH10K_STATE_WEDGED)
+		goto out;
+
+	time_left = wait_event_timeout(arsta->empty_tx_wq, ({
+			bool empty;
+
+			spin_lock_bh(&arsta->sta_tx_lock);
+			empty = (arsta->num_fw_queued == 0);
+			spin_unlock_bh(&arsta->sta_tx_lock);
+
+			skip = (ar->state == ATH10K_STATE_WEDGED) ||
+			       test_bit(ATH10K_FLAG_CRASH_FLUSH,
+					&ar->dev_flags);
+
+			(empty || skip);
+		}), ATH10K_FLUSH_TIMEOUT_HZ);
+
+	if (time_left == 0 || skip)
+		ath10k_warn(ar, "failed to flush sta txq (sta %pM skip %i ar-state %i): %ld\n",
+			    sta->addr, skip, ar->state, time_left);
+out:
+	mutex_unlock(&ar->conf_mutex);
+}
+
 /* TODO: Implement this function properly
  * For now it is needed to reply to Probe Requests in IBSS mode.
  * Probably we need this information from FW.
@@ -9444,6 +9484,7 @@ static const struct ieee80211_ops ath10k_ops = {
 	.set_rts_threshold		= ath10k_set_rts_threshold,
 	.set_frag_threshold		= ath10k_mac_op_set_frag_threshold,
 	.flush				= ath10k_flush,
+	.flush_sta			= ath10k_flush_sta,
 	.tx_last_beacon			= ath10k_tx_last_beacon,
 	.set_antenna			= ath10k_set_antenna,
 	.get_antenna			= ath10k_get_antenna,
diff --git a/drivers/net/wireless/ath/ath10k/txrx.c b/drivers/net/wireless/ath/ath10k/txrx.c
index da3bc35e41aa..ece56379b0f0 100644
--- a/drivers/net/wireless/ath/ath10k/txrx.c
+++ b/drivers/net/wireless/ath/ath10k/txrx.c
@@ -91,6 +91,9 @@ int ath10k_txrx_tx_unref(struct ath10k_htt *htt,
 					       skb_cb->airtime_est, 0);
 	rcu_read_unlock();
 
+	if (txq)
+		ath10k_htt_tx_sta_dec_pending(htt, txq->sta);
+
 	if (ar->bus_param.dev_type != ATH10K_DEV_TYPE_HL)
 		dma_unmap_single(dev, skb_cb->paddr, msdu->len, DMA_TO_DEVICE);
 
-- 
2.40.0

Re: [PATCH 1/2] wifi: ath10k: Implement ieee80211 flush_sta callback

[Jeff Johnson]

On 10/12/2024 7:13 AM, Remi Pommarel wrote:
> When a STA reassociates, mac80211's _sta_info_move_state() waits for all
> pending frame to be flushed before removing the key (so that no frame
> get sent unencrypted after key removable [0]). When a driver does not
> implement the flush_sta callback, ieee80211_flush_queues() is called
> instead which effectively stops the whole queue until it is completely
> drained.
> 
> The ath10k driver configure all STAs of one vdev to share the same
> queue. So when flushing one STA this is the whole vdev queue that is
> blocked until completely drained causing Tx to other STA to also stall
> this whole time.
> 
> One easy way to reproduce the issue is to connect two STAs (STA0 and
> STA1) to an ath10k AP. While Generating a bunch of traffic from AP to
> STA0 (e.g. fping -l -p 20 <STA0-IP>) disconnect STA0 from AP without
> clean disassociation (e.g. remove power, reboot -f). Then as soon as
> STA0 is effectively disconnected from AP (either after inactivity
> timeout or forced with iw dev AP station del STA0), its queues get
> flushed using ieee80211_flush_queues(). This causes STA1 to suffer a
> connectivity stall for about 5 seconds (see ATH10K_FLUSH_TIMEOUT_HZ).
> 
> Implement a flush_sta callback in ath10k to wait only for a specific
> STA pending frames to be drained (without stopping the whole HW queue)
> to fix that.
> 
> [0]: commit 0b75a1b1e42e ("wifi: mac80211: flush queues on STA removal")
> 
> Reported-by: Cedric Veilleux <veilleux.cedric@gmail.com>

checkpatch.pl reports:
WARNING:BAD_REPORTED_BY_LINK: Reported-by: should be immediately followed by Closes: with a URL to the report

> Signed-off-by: Remi Pommarel <repk@triplefau.lt>
> ---
>  drivers/net/wireless/ath/ath10k/core.h   |  4 +++
>  drivers/net/wireless/ath/ath10k/htt.h    |  4 +++
>  drivers/net/wireless/ath/ath10k/htt_tx.c | 32 ++++++++++++++++++
>  drivers/net/wireless/ath/ath10k/mac.c    | 43 +++++++++++++++++++++++-
>  drivers/net/wireless/ath/ath10k/txrx.c   |  3 ++
>  5 files changed, 85 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
> index 446dca74f06a..4709e4887efc 100644
> --- a/drivers/net/wireless/ath/ath10k/core.h
> +++ b/drivers/net/wireless/ath/ath10k/core.h
> @@ -558,6 +558,10 @@ struct ath10k_sta {
>  	u8 rate_ctrl[ATH10K_TID_MAX];
>  	u32 rate_code[ATH10K_TID_MAX];
>  	int rtscts[ATH10K_TID_MAX];
> +	/* protects num_fw_queued */
> +	spinlock_t sta_tx_lock;
> +	wait_queue_head_t empty_tx_wq;
> +	unsigned int num_fw_queued;

is there a reason to prefer a spinlocked value instead of using an atomic without additional locking?

Re: [PATCH 1/2] wifi: ath10k: Implement ieee80211 flush_sta callback

[Remi Pommarel]

On Thu, Oct 17, 2024 at 02:19:51PM -0700, Jeff Johnson wrote:
> On 10/12/2024 7:13 AM, Remi Pommarel wrote:
> > When a STA reassociates, mac80211's _sta_info_move_state() waits for all
> > pending frame to be flushed before removing the key (so that no frame
> > get sent unencrypted after key removable [0]). When a driver does not
> > implement the flush_sta callback, ieee80211_flush_queues() is called
> > instead which effectively stops the whole queue until it is completely
> > drained.
> > 
> > The ath10k driver configure all STAs of one vdev to share the same
> > queue. So when flushing one STA this is the whole vdev queue that is
> > blocked until completely drained causing Tx to other STA to also stall
> > this whole time.
> > 
> > One easy way to reproduce the issue is to connect two STAs (STA0 and
> > STA1) to an ath10k AP. While Generating a bunch of traffic from AP to
> > STA0 (e.g. fping -l -p 20 <STA0-IP>) disconnect STA0 from AP without
> > clean disassociation (e.g. remove power, reboot -f). Then as soon as
> > STA0 is effectively disconnected from AP (either after inactivity
> > timeout or forced with iw dev AP station del STA0), its queues get
> > flushed using ieee80211_flush_queues(). This causes STA1 to suffer a
> > connectivity stall for about 5 seconds (see ATH10K_FLUSH_TIMEOUT_HZ).
> > 
> > Implement a flush_sta callback in ath10k to wait only for a specific
> > STA pending frames to be drained (without stopping the whole HW queue)
> > to fix that.
> > 
> > [0]: commit 0b75a1b1e42e ("wifi: mac80211: flush queues on STA removal")
> > 
> > Reported-by: Cedric Veilleux <veilleux.cedric@gmail.com>
> 
> checkpatch.pl reports:
> WARNING:BAD_REPORTED_BY_LINK: Reported-by: should be immediately followed by Closes: with a URL to the report

It has been reported on mailing list should I put the thread link here ?

> 
> > Signed-off-by: Remi Pommarel <repk@triplefau.lt>
> > ---
> >  drivers/net/wireless/ath/ath10k/core.h   |  4 +++
> >  drivers/net/wireless/ath/ath10k/htt.h    |  4 +++
> >  drivers/net/wireless/ath/ath10k/htt_tx.c | 32 ++++++++++++++++++
> >  drivers/net/wireless/ath/ath10k/mac.c    | 43 +++++++++++++++++++++++-
> >  drivers/net/wireless/ath/ath10k/txrx.c   |  3 ++
> >  5 files changed, 85 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
> > index 446dca74f06a..4709e4887efc 100644
> > --- a/drivers/net/wireless/ath/ath10k/core.h
> > +++ b/drivers/net/wireless/ath/ath10k/core.h
> > @@ -558,6 +558,10 @@ struct ath10k_sta {
> >  	u8 rate_ctrl[ATH10K_TID_MAX];
> >  	u32 rate_code[ATH10K_TID_MAX];
> >  	int rtscts[ATH10K_TID_MAX];
> > +	/* protects num_fw_queued */
> > +	spinlock_t sta_tx_lock;
> > +	wait_queue_head_t empty_tx_wq;
> > +	unsigned int num_fw_queued;
> 
> is there a reason to prefer a spinlocked value instead of using an atomic without additional locking?

No reason except to mimic what is done for num_pending. Can move that to
atomic if needed be.

Thanks,

-- 
Remi

Re: [PATCH 1/2] wifi: ath10k: Implement ieee80211 flush_sta callback

[Vasanthakumar Thiagarajan]

On 10/12/2024 7:43 PM, Remi Pommarel wrote:
> When a STA reassociates, mac80211's _sta_info_move_state() waits for all
> pending frame to be flushed before removing the key (so that no frame
> get sent unencrypted after key removable [0]). When a driver does not
> implement the flush_sta callback, ieee80211_flush_queues() is called
> instead which effectively stops the whole queue until it is completely
> drained.
> 
> The ath10k driver configure all STAs of one vdev to share the same
> queue. So when flushing one STA this is the whole vdev queue that is
> blocked until completely drained causing Tx to other STA to also stall
> this whole time.
> 
> One easy way to reproduce the issue is to connect two STAs (STA0 and
> STA1) to an ath10k AP. While Generating a bunch of traffic from AP to
> STA0 (e.g. fping -l -p 20 <STA0-IP>) disconnect STA0 from AP without
> clean disassociation (e.g. remove power, reboot -f). Then as soon as
> STA0 is effectively disconnected from AP (either after inactivity
> timeout or forced with iw dev AP station del STA0), its queues get
> flushed using ieee80211_flush_queues(). This causes STA1 to suffer a
> connectivity stall for about 5 seconds (see ATH10K_FLUSH_TIMEOUT_HZ).
> 
> Implement a flush_sta callback in ath10k to wait only for a specific
> STA pending frames to be drained (without stopping the whole HW queue)
> to fix that.
> 
> [0]: commit 0b75a1b1e42e ("wifi: mac80211: flush queues on STA removal")
> 
> Reported-by: Cedric Veilleux <veilleux.cedric@gmail.com>
> Signed-off-by: Remi Pommarel <repk@triplefau.lt>
> ---
>   drivers/net/wireless/ath/ath10k/core.h   |  4 +++
>   drivers/net/wireless/ath/ath10k/htt.h    |  4 +++
>   drivers/net/wireless/ath/ath10k/htt_tx.c | 32 ++++++++++++++++++
>   drivers/net/wireless/ath/ath10k/mac.c    | 43 +++++++++++++++++++++++-
>   drivers/net/wireless/ath/ath10k/txrx.c   |  3 ++
>   5 files changed, 85 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
> index 446dca74f06a..4709e4887efc 100644
> --- a/drivers/net/wireless/ath/ath10k/core.h
> +++ b/drivers/net/wireless/ath/ath10k/core.h
> @@ -558,6 +558,10 @@ struct ath10k_sta {
>   	u8 rate_ctrl[ATH10K_TID_MAX];
>   	u32 rate_code[ATH10K_TID_MAX];
>   	int rtscts[ATH10K_TID_MAX];
> +	/* protects num_fw_queued */
> +	spinlock_t sta_tx_lock;
> +	wait_queue_head_t empty_tx_wq;
> +	unsigned int num_fw_queued;
>   };
>   
>   #define ATH10K_VDEV_SETUP_TIMEOUT_HZ	(5 * HZ)
> diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
> index 603f6de62b0a..d150f9330941 100644
> --- a/drivers/net/wireless/ath/ath10k/htt.h
> +++ b/drivers/net/wireless/ath/ath10k/htt.h
> @@ -2452,6 +2452,10 @@ int ath10k_htt_tx_inc_pending(struct ath10k_htt *htt);
>   void ath10k_htt_tx_mgmt_dec_pending(struct ath10k_htt *htt);
>   int ath10k_htt_tx_mgmt_inc_pending(struct ath10k_htt *htt, bool is_mgmt,
>   				   bool is_presp);
> +void ath10k_htt_tx_sta_inc_pending(struct ath10k_htt *htt,
> +				   struct ieee80211_sta *sta);
> +void ath10k_htt_tx_sta_dec_pending(struct ath10k_htt *htt,
> +				   struct ieee80211_sta *sta);
>   
>   int ath10k_htt_tx_alloc_msdu_id(struct ath10k_htt *htt, struct sk_buff *skb);
>   void ath10k_htt_tx_free_msdu_id(struct ath10k_htt *htt, u16 msdu_id);
> diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
> index 9725feecefd6..7477cb8f5d10 100644
> --- a/drivers/net/wireless/ath/ath10k/htt_tx.c
> +++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
> @@ -195,6 +195,38 @@ void ath10k_htt_tx_mgmt_dec_pending(struct ath10k_htt *htt)
>   	htt->num_pending_mgmt_tx--;
>   }
>   
> +void ath10k_htt_tx_sta_inc_pending(struct ath10k_htt *htt,
> +				   struct ieee80211_sta *sta)
> +{
> +	struct ath10k_sta *arsta;
> +
> +	if (!sta)
> +		return;
> +
> +	arsta = (struct ath10k_sta *)sta->drv_priv;
> +
> +	spin_lock_bh(&arsta->sta_tx_lock);
> +	arsta->num_fw_queued++;
> +	spin_unlock_bh(&arsta->sta_tx_lock);
> +}
> +
> +void ath10k_htt_tx_sta_dec_pending(struct ath10k_htt *htt,
> +				   struct ieee80211_sta *sta)
> +{
> +	struct ath10k_sta *arsta;
> +
> +	if (!sta)
> +		return;
> +
> +	arsta = (struct ath10k_sta *)sta->drv_priv;
> +
> +	spin_lock_bh(&arsta->sta_tx_lock);
> +	arsta->num_fw_queued--;
> +	if (arsta->num_fw_queued == 0)
> +		wake_up(&arsta->empty_tx_wq);
> +	spin_unlock_bh(&arsta->sta_tx_lock);
> +}
> +
>   int ath10k_htt_tx_alloc_msdu_id(struct ath10k_htt *htt, struct sk_buff *skb)
>   {
>   	struct ath10k *ar = htt->ar;
> diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
> index 646e1737d4c4..373a0aa6b01c 100644
> --- a/drivers/net/wireless/ath/ath10k/mac.c
> +++ b/drivers/net/wireless/ath/ath10k/mac.c
> @@ -4423,6 +4423,8 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
>   		spin_unlock_bh(&ar->htt.tx_lock);
>   	}
>   
> +	ath10k_htt_tx_sta_inc_pending(&ar->htt, sta);
> +
>   	ret = ath10k_mac_tx(ar, vif, txmode, txpath, skb, false);
>   	if (unlikely(ret)) {
>   		ath10k_warn(ar, "failed to push frame: %d\n", ret);
> @@ -4432,6 +4434,7 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
>   		if (is_mgmt)
>   			ath10k_htt_tx_mgmt_dec_pending(htt);
>   		spin_unlock_bh(&ar->htt.tx_lock);
> +		ath10k_htt_tx_sta_dec_pending(&ar->htt, sta);
>   
>   		return ret;
>   	}
> @@ -7474,7 +7477,8 @@ static int ath10k_sta_state(struct ieee80211_hw *hw,
>   		arsta->peer_ps_state = WMI_PEER_PS_STATE_DISABLED;
>   		INIT_WORK(&arsta->update_wk, ath10k_sta_rc_update_wk);
>   		INIT_WORK(&arsta->tid_config_wk, ath10k_sta_tid_cfg_wk);
> -
> +		spin_lock_init(&arsta->sta_tx_lock);
> +		init_waitqueue_head(&arsta->empty_tx_wq);
>   		for (i = 0; i < ARRAY_SIZE(sta->txq); i++)
>   			ath10k_mac_txq_init(sta->txq[i]);
>   	}
> @@ -8098,6 +8102,42 @@ static void ath10k_flush(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
>   	mutex_unlock(&ar->conf_mutex);
>   }
>   
> +static void ath10k_flush_sta(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
> +			     struct ieee80211_sta *sta)
> +{
> +	struct ath10k_sta *arsta = (struct ath10k_sta *)sta->drv_priv;
> +	struct ath10k *ar = hw->priv;
> +	bool skip;
> +	long time_left;
> +
> +	/* TODO do we need drop implemented here ? */
> +
> +	mutex_lock(&ar->conf_mutex);
> +
> +	if (ar->state == ATH10K_STATE_WEDGED)
> +		goto out;
> +
> +	time_left = wait_event_timeout(arsta->empty_tx_wq, ({
> +			bool empty;
> +
> +			spin_lock_bh(&arsta->sta_tx_lock);
> +			empty = (arsta->num_fw_queued == 0);
> +			spin_unlock_bh(&arsta->sta_tx_lock);
> +
> +			skip = (ar->state == ATH10K_STATE_WEDGED) ||
> +			       test_bit(ATH10K_FLAG_CRASH_FLUSH,
> +					&ar->dev_flags);
> +
> +			(empty || skip);
> +		}), ATH10K_FLUSH_TIMEOUT_HZ);
> +
> +	if (time_left == 0 || skip)
> +		ath10k_warn(ar, "failed to flush sta txq (sta %pM skip %i ar-state %i): %ld\n",
> +			    sta->addr, skip, ar->state, time_left);
> +out:
> +	mutex_unlock(&ar->conf_mutex);
> +}
> +
>   /* TODO: Implement this function properly
>    * For now it is needed to reply to Probe Requests in IBSS mode.
>    * Probably we need this information from FW.
> @@ -9444,6 +9484,7 @@ static const struct ieee80211_ops ath10k_ops = {
>   	.set_rts_threshold		= ath10k_set_rts_threshold,
>   	.set_frag_threshold		= ath10k_mac_op_set_frag_threshold,
>   	.flush				= ath10k_flush,
> +	.flush_sta			= ath10k_flush_sta,
>   	.tx_last_beacon			= ath10k_tx_last_beacon,
>   	.set_antenna			= ath10k_set_antenna,
>   	.get_antenna			= ath10k_get_antenna,
> diff --git a/drivers/net/wireless/ath/ath10k/txrx.c b/drivers/net/wireless/ath/ath10k/txrx.c
> index da3bc35e41aa..ece56379b0f0 100644
> --- a/drivers/net/wireless/ath/ath10k/txrx.c
> +++ b/drivers/net/wireless/ath/ath10k/txrx.c
> @@ -91,6 +91,9 @@ int ath10k_txrx_tx_unref(struct ath10k_htt *htt,
>   					       skb_cb->airtime_est, 0);
>   	rcu_read_unlock();
>   
> +	if (txq)
> +		ath10k_htt_tx_sta_dec_pending(htt, txq->sta);
> +

This should be called within rcu?

Vasanth

Re: [PATCH 1/2] wifi: ath10k: Implement ieee80211 flush_sta callback

[Remi Pommarel]

On Fri, Oct 18, 2024 at 12:57:48PM +0530, Vasanthakumar Thiagarajan wrote:
> 
> 
> On 10/12/2024 7:43 PM, Remi Pommarel wrote:
> > When a STA reassociates, mac80211's _sta_info_move_state() waits for all
> > pending frame to be flushed before removing the key (so that no frame
> > get sent unencrypted after key removable [0]). When a driver does not
> > implement the flush_sta callback, ieee80211_flush_queues() is called
> > instead which effectively stops the whole queue until it is completely
> > drained.
> > 
> > The ath10k driver configure all STAs of one vdev to share the same
> > queue. So when flushing one STA this is the whole vdev queue that is
> > blocked until completely drained causing Tx to other STA to also stall
> > this whole time.
> > 
> > One easy way to reproduce the issue is to connect two STAs (STA0 and
> > STA1) to an ath10k AP. While Generating a bunch of traffic from AP to
> > STA0 (e.g. fping -l -p 20 <STA0-IP>) disconnect STA0 from AP without
> > clean disassociation (e.g. remove power, reboot -f). Then as soon as
> > STA0 is effectively disconnected from AP (either after inactivity
> > timeout or forced with iw dev AP station del STA0), its queues get
> > flushed using ieee80211_flush_queues(). This causes STA1 to suffer a
> > connectivity stall for about 5 seconds (see ATH10K_FLUSH_TIMEOUT_HZ).
> > 
> > Implement a flush_sta callback in ath10k to wait only for a specific
> > STA pending frames to be drained (without stopping the whole HW queue)
> > to fix that.
> > 
> > [0]: commit 0b75a1b1e42e ("wifi: mac80211: flush queues on STA removal")
> > 
> > Reported-by: Cedric Veilleux <veilleux.cedric@gmail.com>
> > Signed-off-by: Remi Pommarel <repk@triplefau.lt>
> > ---
> >   drivers/net/wireless/ath/ath10k/core.h   |  4 +++
> >   drivers/net/wireless/ath/ath10k/htt.h    |  4 +++
> >   drivers/net/wireless/ath/ath10k/htt_tx.c | 32 ++++++++++++++++++
> >   drivers/net/wireless/ath/ath10k/mac.c    | 43 +++++++++++++++++++++++-
> >   drivers/net/wireless/ath/ath10k/txrx.c   |  3 ++
> >   5 files changed, 85 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
> > index 446dca74f06a..4709e4887efc 100644
> > --- a/drivers/net/wireless/ath/ath10k/core.h
> > +++ b/drivers/net/wireless/ath/ath10k/core.h
> > @@ -558,6 +558,10 @@ struct ath10k_sta {
> >   	u8 rate_ctrl[ATH10K_TID_MAX];
> >   	u32 rate_code[ATH10K_TID_MAX];
> >   	int rtscts[ATH10K_TID_MAX];
> > +	/* protects num_fw_queued */
> > +	spinlock_t sta_tx_lock;
> > +	wait_queue_head_t empty_tx_wq;
> > +	unsigned int num_fw_queued;
> >   };
> >   #define ATH10K_VDEV_SETUP_TIMEOUT_HZ	(5 * HZ)
> > diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
> > index 603f6de62b0a..d150f9330941 100644
> > --- a/drivers/net/wireless/ath/ath10k/htt.h
> > +++ b/drivers/net/wireless/ath/ath10k/htt.h
> > @@ -2452,6 +2452,10 @@ int ath10k_htt_tx_inc_pending(struct ath10k_htt *htt);
> >   void ath10k_htt_tx_mgmt_dec_pending(struct ath10k_htt *htt);
> >   int ath10k_htt_tx_mgmt_inc_pending(struct ath10k_htt *htt, bool is_mgmt,
> >   				   bool is_presp);
> > +void ath10k_htt_tx_sta_inc_pending(struct ath10k_htt *htt,
> > +				   struct ieee80211_sta *sta);
> > +void ath10k_htt_tx_sta_dec_pending(struct ath10k_htt *htt,
> > +				   struct ieee80211_sta *sta);
> >   int ath10k_htt_tx_alloc_msdu_id(struct ath10k_htt *htt, struct sk_buff *skb);
> >   void ath10k_htt_tx_free_msdu_id(struct ath10k_htt *htt, u16 msdu_id);
> > diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
> > index 9725feecefd6..7477cb8f5d10 100644
> > --- a/drivers/net/wireless/ath/ath10k/htt_tx.c
> > +++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
> > @@ -195,6 +195,38 @@ void ath10k_htt_tx_mgmt_dec_pending(struct ath10k_htt *htt)
> >   	htt->num_pending_mgmt_tx--;
> >   }
> > +void ath10k_htt_tx_sta_inc_pending(struct ath10k_htt *htt,
> > +				   struct ieee80211_sta *sta)
> > +{
> > +	struct ath10k_sta *arsta;
> > +
> > +	if (!sta)
> > +		return;
> > +
> > +	arsta = (struct ath10k_sta *)sta->drv_priv;
> > +
> > +	spin_lock_bh(&arsta->sta_tx_lock);
> > +	arsta->num_fw_queued++;
> > +	spin_unlock_bh(&arsta->sta_tx_lock);
> > +}
> > +
> > +void ath10k_htt_tx_sta_dec_pending(struct ath10k_htt *htt,
> > +				   struct ieee80211_sta *sta)
> > +{
> > +	struct ath10k_sta *arsta;
> > +
> > +	if (!sta)
> > +		return;
> > +
> > +	arsta = (struct ath10k_sta *)sta->drv_priv;
> > +
> > +	spin_lock_bh(&arsta->sta_tx_lock);
> > +	arsta->num_fw_queued--;
> > +	if (arsta->num_fw_queued == 0)
> > +		wake_up(&arsta->empty_tx_wq);
> > +	spin_unlock_bh(&arsta->sta_tx_lock);
> > +}
> > +
> >   int ath10k_htt_tx_alloc_msdu_id(struct ath10k_htt *htt, struct sk_buff *skb)
> >   {
> >   	struct ath10k *ar = htt->ar;
> > diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
> > index 646e1737d4c4..373a0aa6b01c 100644
> > --- a/drivers/net/wireless/ath/ath10k/mac.c
> > +++ b/drivers/net/wireless/ath/ath10k/mac.c
> > @@ -4423,6 +4423,8 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
> >   		spin_unlock_bh(&ar->htt.tx_lock);
> >   	}
> > +	ath10k_htt_tx_sta_inc_pending(&ar->htt, sta);
> > +
> >   	ret = ath10k_mac_tx(ar, vif, txmode, txpath, skb, false);
> >   	if (unlikely(ret)) {
> >   		ath10k_warn(ar, "failed to push frame: %d\n", ret);
> > @@ -4432,6 +4434,7 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
> >   		if (is_mgmt)
> >   			ath10k_htt_tx_mgmt_dec_pending(htt);
> >   		spin_unlock_bh(&ar->htt.tx_lock);
> > +		ath10k_htt_tx_sta_dec_pending(&ar->htt, sta);
> >   		return ret;
> >   	}
> > @@ -7474,7 +7477,8 @@ static int ath10k_sta_state(struct ieee80211_hw *hw,
> >   		arsta->peer_ps_state = WMI_PEER_PS_STATE_DISABLED;
> >   		INIT_WORK(&arsta->update_wk, ath10k_sta_rc_update_wk);
> >   		INIT_WORK(&arsta->tid_config_wk, ath10k_sta_tid_cfg_wk);
> > -
> > +		spin_lock_init(&arsta->sta_tx_lock);
> > +		init_waitqueue_head(&arsta->empty_tx_wq);
> >   		for (i = 0; i < ARRAY_SIZE(sta->txq); i++)
> >   			ath10k_mac_txq_init(sta->txq[i]);
> >   	}
> > @@ -8098,6 +8102,42 @@ static void ath10k_flush(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
> >   	mutex_unlock(&ar->conf_mutex);
> >   }
> > +static void ath10k_flush_sta(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
> > +			     struct ieee80211_sta *sta)
> > +{
> > +	struct ath10k_sta *arsta = (struct ath10k_sta *)sta->drv_priv;
> > +	struct ath10k *ar = hw->priv;
> > +	bool skip;
> > +	long time_left;
> > +
> > +	/* TODO do we need drop implemented here ? */
> > +
> > +	mutex_lock(&ar->conf_mutex);
> > +
> > +	if (ar->state == ATH10K_STATE_WEDGED)
> > +		goto out;
> > +
> > +	time_left = wait_event_timeout(arsta->empty_tx_wq, ({
> > +			bool empty;
> > +
> > +			spin_lock_bh(&arsta->sta_tx_lock);
> > +			empty = (arsta->num_fw_queued == 0);
> > +			spin_unlock_bh(&arsta->sta_tx_lock);
> > +
> > +			skip = (ar->state == ATH10K_STATE_WEDGED) ||
> > +			       test_bit(ATH10K_FLAG_CRASH_FLUSH,
> > +					&ar->dev_flags);
> > +
> > +			(empty || skip);
> > +		}), ATH10K_FLUSH_TIMEOUT_HZ);
> > +
> > +	if (time_left == 0 || skip)
> > +		ath10k_warn(ar, "failed to flush sta txq (sta %pM skip %i ar-state %i): %ld\n",
> > +			    sta->addr, skip, ar->state, time_left);
> > +out:
> > +	mutex_unlock(&ar->conf_mutex);
> > +}
> > +
> >   /* TODO: Implement this function properly
> >    * For now it is needed to reply to Probe Requests in IBSS mode.
> >    * Probably we need this information from FW.
> > @@ -9444,6 +9484,7 @@ static const struct ieee80211_ops ath10k_ops = {
> >   	.set_rts_threshold		= ath10k_set_rts_threshold,
> >   	.set_frag_threshold		= ath10k_mac_op_set_frag_threshold,
> >   	.flush				= ath10k_flush,
> > +	.flush_sta			= ath10k_flush_sta,
> >   	.tx_last_beacon			= ath10k_tx_last_beacon,
> >   	.set_antenna			= ath10k_set_antenna,
> >   	.get_antenna			= ath10k_get_antenna,
> > diff --git a/drivers/net/wireless/ath/ath10k/txrx.c b/drivers/net/wireless/ath/ath10k/txrx.c
> > index da3bc35e41aa..ece56379b0f0 100644
> > --- a/drivers/net/wireless/ath/ath10k/txrx.c
> > +++ b/drivers/net/wireless/ath/ath10k/txrx.c
> > @@ -91,6 +91,9 @@ int ath10k_txrx_tx_unref(struct ath10k_htt *htt,
> >   					       skb_cb->airtime_est, 0);
> >   	rcu_read_unlock();
> > +	if (txq)
> > +		ath10k_htt_tx_sta_dec_pending(htt, txq->sta);
> > +
> 
> This should be called within rcu?

According to [0] yes. But not sure to understand how that fixes the null
pointer dereference here as txq->sta is never set to NULL elsewhere and
no rcu_dereference is used in rcu critical section. The only things I
can think of is that it delays sta memory release past the rcu section.
So yes maybe it is safer (and harmless) to put that within rcu read
lock.

Waiting to know if sta pending should be atomic instead of spinlock
protected and send v2 accordingly.

Thanks

[0]: commit acb31476adc9f ("ath10k: fix kernel null pointer dereference")

-- 
Remi

-- 
Remi

[PATCH 2/2] wifi: ath10k: Flush only requested txq in ath10k_flush()

[Remi Pommarel]

The ieee80211 flush callback can be called to flush only part of all hw
queues. The ath10k's flush callback implementation (i.e. ath10k_flush())
was waiting for all pending frames of all queues to be flushed ignoring
the queue parameter. Because only the queues to be flushed are stopped
by mac80211, skb can still be queued to other queues meanwhile. Thus
ath10k_flush() could fail (and wait 5sec holding ar->conf lock) even if
the requested queues are flushed correctly.

A way to reproduce the issue is to use two different APs because
each vdev has its own hw queue in ath10k. Connect STA0 to AP0 and STA1
to AP1. Then generate traffic from AP0 to STA0 and kill STA0 without
clean disassociation frame (e.g. unplug power cable, reboot -f, ...).
Now if we were to flush AP1's queue, ath10k_flush() would fail (and
effectively block 5 seconds with ar->conf or even wiphy's lock held)
with the following warning:

 ath10k_pci 0000:01:00.0: failed to flush transmit queue (skip 0 ar-state 2): 0

Wait only for pending frames of the requested queues to be flushed in
ath10k_flush() to avoid that long blocking.

Reported-by: Cedric Veilleux <veilleux.cedric@gmail.com>
Signed-off-by: Remi Pommarel <repk@triplefau.lt>
---
 drivers/net/wireless/ath/ath10k/htt.h    |  7 +++--
 drivers/net/wireless/ath/ath10k/htt_tx.c | 18 ++++++++++---
 drivers/net/wireless/ath/ath10k/mac.c    | 33 +++++++++++++++++-------
 drivers/net/wireless/ath/ath10k/txrx.c   |  2 +-
 4 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
index d150f9330941..33054fc4d9fb 100644
--- a/drivers/net/wireless/ath/ath10k/htt.h
+++ b/drivers/net/wireless/ath/ath10k/htt.h
@@ -1870,6 +1870,7 @@ struct ath10k_htt {
 	spinlock_t tx_lock;
 	int max_num_pending_tx;
 	int num_pending_tx;
+	int pending_per_queue[IEEE80211_MAX_QUEUES];
 	int num_pending_mgmt_tx;
 	struct idr pending_tx;
 	wait_queue_head_t empty_tx_wq;
@@ -2447,8 +2448,10 @@ void ath10k_htt_tx_txq_update(struct ieee80211_hw *hw,
 void ath10k_htt_tx_txq_recalc(struct ieee80211_hw *hw,
 			      struct ieee80211_txq *txq);
 void ath10k_htt_tx_txq_sync(struct ath10k *ar);
-void ath10k_htt_tx_dec_pending(struct ath10k_htt *htt);
-int ath10k_htt_tx_inc_pending(struct ath10k_htt *htt);
+void ath10k_htt_tx_dec_pending(struct ath10k_htt *htt,
+			       struct ieee80211_txq *txq);
+int ath10k_htt_tx_inc_pending(struct ath10k_htt *htt,
+			      struct ieee80211_txq *txq);
 void ath10k_htt_tx_mgmt_dec_pending(struct ath10k_htt *htt);
 int ath10k_htt_tx_mgmt_inc_pending(struct ath10k_htt *htt, bool is_mgmt,
 				   bool is_presp);
diff --git a/drivers/net/wireless/ath/ath10k/htt_tx.c b/drivers/net/wireless/ath/ath10k/htt_tx.c
index 7477cb8f5d10..a87ceda86098 100644
--- a/drivers/net/wireless/ath/ath10k/htt_tx.c
+++ b/drivers/net/wireless/ath/ath10k/htt_tx.c
@@ -140,19 +140,26 @@ void ath10k_htt_tx_txq_update(struct ieee80211_hw *hw,
 	spin_unlock_bh(&ar->htt.tx_lock);
 }
 
-void ath10k_htt_tx_dec_pending(struct ath10k_htt *htt)
+void ath10k_htt_tx_dec_pending(struct ath10k_htt *htt,
+			       struct ieee80211_txq *txq)
 {
+	int num_txq = -1;
+
 	lockdep_assert_held(&htt->tx_lock);
 
 	htt->num_pending_tx--;
 	if (htt->num_pending_tx == htt->max_num_pending_tx - 1)
 		ath10k_mac_tx_unlock(htt->ar, ATH10K_TX_PAUSE_Q_FULL);
 
-	if (htt->num_pending_tx == 0)
+	if (txq)
+		num_txq = --htt->pending_per_queue[txq->vif->hw_queue[txq->ac]];
+
+	if (htt->num_pending_tx == 0 || num_txq == 0)
 		wake_up(&htt->empty_tx_wq);
 }
 
-int ath10k_htt_tx_inc_pending(struct ath10k_htt *htt)
+int ath10k_htt_tx_inc_pending(struct ath10k_htt *htt,
+			      struct ieee80211_txq *txq)
 {
 	lockdep_assert_held(&htt->tx_lock);
 
@@ -163,6 +170,11 @@ int ath10k_htt_tx_inc_pending(struct ath10k_htt *htt)
 	if (htt->num_pending_tx == htt->max_num_pending_tx)
 		ath10k_mac_tx_lock(htt->ar, ATH10K_TX_PAUSE_Q_FULL);
 
+	if (!txq)
+		return 0;
+
+	htt->pending_per_queue[txq->vif->hw_queue[txq->ac]]++;
+
 	return 0;
 }
 
diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
index 373a0aa6b01c..bb4a6f11dd1d 100644
--- a/drivers/net/wireless/ath/ath10k/mac.c
+++ b/drivers/net/wireless/ath/ath10k/mac.c
@@ -4385,7 +4385,7 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
 	u16 airtime;
 
 	spin_lock_bh(&ar->htt.tx_lock);
-	ret = ath10k_htt_tx_inc_pending(htt);
+	ret = ath10k_htt_tx_inc_pending(htt, txq);
 	spin_unlock_bh(&ar->htt.tx_lock);
 
 	if (ret)
@@ -4394,7 +4394,7 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
 	skb = ieee80211_tx_dequeue_ni(hw, txq);
 	if (!skb) {
 		spin_lock_bh(&ar->htt.tx_lock);
-		ath10k_htt_tx_dec_pending(htt);
+		ath10k_htt_tx_dec_pending(htt, txq);
 		spin_unlock_bh(&ar->htt.tx_lock);
 
 		return -ENOENT;
@@ -4416,7 +4416,7 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
 		ret = ath10k_htt_tx_mgmt_inc_pending(htt, is_mgmt, is_presp);
 
 		if (ret) {
-			ath10k_htt_tx_dec_pending(htt);
+			ath10k_htt_tx_dec_pending(htt, txq);
 			spin_unlock_bh(&ar->htt.tx_lock);
 			return ret;
 		}
@@ -4430,7 +4430,7 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
 		ath10k_warn(ar, "failed to push frame: %d\n", ret);
 
 		spin_lock_bh(&ar->htt.tx_lock);
-		ath10k_htt_tx_dec_pending(htt);
+		ath10k_htt_tx_dec_pending(htt, txq);
 		if (is_mgmt)
 			ath10k_htt_tx_mgmt_dec_pending(htt);
 		spin_unlock_bh(&ar->htt.tx_lock);
@@ -4693,7 +4693,7 @@ static void ath10k_mac_op_tx(struct ieee80211_hw *hw,
 			is_presp = ieee80211_is_probe_resp(hdr->frame_control);
 		}
 
-		ret = ath10k_htt_tx_inc_pending(htt);
+		ret = ath10k_htt_tx_inc_pending(htt, txq);
 		if (ret) {
 			ath10k_warn(ar, "failed to increase tx pending count: %d, dropping\n",
 				    ret);
@@ -4706,7 +4706,7 @@ static void ath10k_mac_op_tx(struct ieee80211_hw *hw,
 		if (ret) {
 			ath10k_dbg(ar, ATH10K_DBG_MAC, "failed to increase tx mgmt pending count: %d, dropping\n",
 				   ret);
-			ath10k_htt_tx_dec_pending(htt);
+			ath10k_htt_tx_dec_pending(htt, txq);
 			spin_unlock_bh(&ar->htt.tx_lock);
 			ieee80211_free_txskb(ar->hw, skb);
 			return;
@@ -4719,7 +4719,7 @@ static void ath10k_mac_op_tx(struct ieee80211_hw *hw,
 		ath10k_warn(ar, "failed to transmit frame: %d\n", ret);
 		if (is_htt) {
 			spin_lock_bh(&ar->htt.tx_lock);
-			ath10k_htt_tx_dec_pending(htt);
+			ath10k_htt_tx_dec_pending(htt, txq);
 			if (is_mgmt)
 				ath10k_htt_tx_mgmt_dec_pending(htt);
 			spin_unlock_bh(&ar->htt.tx_lock);
@@ -8046,10 +8046,12 @@ static int ath10k_mac_op_set_frag_threshold(struct ieee80211_hw *hw, u32 value)
 	return -EOPNOTSUPP;
 }
 
-void ath10k_mac_wait_tx_complete(struct ath10k *ar)
+static void _ath10k_mac_wait_tx_complete(struct ath10k *ar,
+					 unsigned long queues)
 {
 	bool skip;
 	long time_left;
+	unsigned int q;
 
 	/* mac80211 doesn't care if we really xmit queued frames or not
 	 * we'll collect those frames either way if we stop/delete vdevs
@@ -8062,7 +8064,11 @@ void ath10k_mac_wait_tx_complete(struct ath10k *ar)
 			bool empty;
 
 			spin_lock_bh(&ar->htt.tx_lock);
-			empty = (ar->htt.num_pending_tx == 0);
+			for_each_set_bit(q, &queues, ar->hw->queues) {
+				empty = (ar->htt.pending_per_queue[q] == 0);
+				if (!empty)
+					break;
+			}
 			spin_unlock_bh(&ar->htt.tx_lock);
 
 			skip = (ar->state == ATH10K_STATE_WEDGED) ||
@@ -8077,6 +8083,13 @@ void ath10k_mac_wait_tx_complete(struct ath10k *ar)
 			    skip, ar->state, time_left);
 }
 
+void ath10k_mac_wait_tx_complete(struct ath10k *ar)
+{
+	unsigned int queues = GENMASK(ar->hw->queues - 1, 0);
+
+	_ath10k_mac_wait_tx_complete(ar, queues);
+}
+
 static void ath10k_flush(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 			 u32 queues, bool drop)
 {
@@ -8098,7 +8111,7 @@ static void ath10k_flush(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	}
 
 	mutex_lock(&ar->conf_mutex);
-	ath10k_mac_wait_tx_complete(ar);
+	_ath10k_mac_wait_tx_complete(ar, queues);
 	mutex_unlock(&ar->conf_mutex);
 }
 
diff --git a/drivers/net/wireless/ath/ath10k/txrx.c b/drivers/net/wireless/ath/ath10k/txrx.c
index ece56379b0f0..5b5078cff153 100644
--- a/drivers/net/wireless/ath/ath10k/txrx.c
+++ b/drivers/net/wireless/ath/ath10k/txrx.c
@@ -82,7 +82,7 @@ int ath10k_txrx_tx_unref(struct ath10k_htt *htt,
 
 	flags = skb_cb->flags;
 	ath10k_htt_tx_free_msdu_id(htt, tx_done->msdu_id);
-	ath10k_htt_tx_dec_pending(htt);
+	ath10k_htt_tx_dec_pending(htt, txq);
 	spin_unlock_bh(&htt->tx_lock);
 
 	rcu_read_lock();
-- 
2.40.0

Re: [PATCH 2/2] wifi: ath10k: Flush only requested txq in ath10k_flush()

[Jeff Johnson]

On 10/12/2024 7:13 AM, Remi Pommarel wrote:
> The ieee80211 flush callback can be called to flush only part of all hw
> queues. The ath10k's flush callback implementation (i.e. ath10k_flush())
> was waiting for all pending frames of all queues to be flushed ignoring
> the queue parameter. Because only the queues to be flushed are stopped
> by mac80211, skb can still be queued to other queues meanwhile. Thus
> ath10k_flush() could fail (and wait 5sec holding ar->conf lock) even if
> the requested queues are flushed correctly.
> 
> A way to reproduce the issue is to use two different APs because
> each vdev has its own hw queue in ath10k. Connect STA0 to AP0 and STA1
> to AP1. Then generate traffic from AP0 to STA0 and kill STA0 without
> clean disassociation frame (e.g. unplug power cable, reboot -f, ...).
> Now if we were to flush AP1's queue, ath10k_flush() would fail (and
> effectively block 5 seconds with ar->conf or even wiphy's lock held)
> with the following warning:
> 
>  ath10k_pci 0000:01:00.0: failed to flush transmit queue (skip 0 ar-state 2): 0
> 
> Wait only for pending frames of the requested queues to be flushed in
> ath10k_flush() to avoid that long blocking.
> 
> Reported-by: Cedric Veilleux <veilleux.cedric@gmail.com>

WARNING:BAD_REPORTED_BY_LINK: Reported-by: should be immediately followed by Closes: with a URL to the report

> Signed-off-by: Remi Pommarel <repk@triplefau.lt>
> ---
>  drivers/net/wireless/ath/ath10k/htt.h    |  7 +++--
>  drivers/net/wireless/ath/ath10k/htt_tx.c | 18 ++++++++++---
>  drivers/net/wireless/ath/ath10k/mac.c    | 33 +++++++++++++++++-------
>  drivers/net/wireless/ath/ath10k/txrx.c   |  2 +-
>  4 files changed, 44 insertions(+), 16 deletions(-)

Re: [PATCH 2/2] wifi: ath10k: Flush only requested txq in ath10k_flush()

[Vasanthakumar Thiagarajan]

On 10/12/2024 7:43 PM, Remi Pommarel wrote:
> The ieee80211 flush callback can be called to flush only part of all hw
> queues. The ath10k's flush callback implementation (i.e. ath10k_flush())
> was waiting for all pending frames of all queues to be flushed ignoring
> the queue parameter. Because only the queues to be flushed are stopped
> by mac80211, skb can still be queued to other queues meanwhile. Thus
> ath10k_flush() could fail (and wait 5sec holding ar->conf lock) even if
> the requested queues are flushed correctly.
> 
> A way to reproduce the issue is to use two different APs because
> each vdev has its own hw queue in ath10k. Connect STA0 to AP0 and STA1
> to AP1. Then generate traffic from AP0 to STA0 and kill STA0 without
> clean disassociation frame (e.g. unplug power cable, reboot -f, ...).
> Now if we were to flush AP1's queue, ath10k_flush() would fail (and
> effectively block 5 seconds with ar->conf or even wiphy's lock held)
> with the following warning:
> 
>   ath10k_pci 0000:01:00.0: failed to flush transmit queue (skip 0 ar-state 2): 0
> 
> Wait only for pending frames of the requested queues to be flushed in
> ath10k_flush() to avoid that long blocking.
> 
> Reported-by: Cedric Veilleux <veilleux.cedric@gmail.com>
> Signed-off-by: Remi Pommarel <repk@triplefau.lt>
> ---
>   drivers/net/wireless/ath/ath10k/htt.h    |  7 +++--
>   drivers/net/wireless/ath/ath10k/htt_tx.c | 18 ++++++++++---
>   drivers/net/wireless/ath/ath10k/mac.c    | 33 +++++++++++++++++-------
>   drivers/net/wireless/ath/ath10k/txrx.c   |  2 +-
>   4 files changed, 44 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
> index d150f9330941..33054fc4d9fb 100644
> --- a/drivers/net/wireless/ath/ath10k/htt.h
> +++ b/drivers/net/wireless/ath/ath10k/htt.h
> @@ -1870,6 +1870,7 @@ struct ath10k_htt {
>   	spinlock_t tx_lock;
>   	int max_num_pending_tx;
>   	int num_pending_tx;
> +	int pending_per_queue[IEEE80211_MAX_QUEUES];

Something like num_pending_per_queue[] to align with the existing
packet counter looks better?

Vasanth

Re: [PATCH 0/2] Improve ath10k flush queue mechanism

[Jeff Johnson]

On 10/12/2024 7:13 AM, Remi Pommarel wrote:
> It has been reported [0] that a 3-4 seconds (actually up to 5 sec) of
> radio silence could be observed followed by the error below on ath10k
> devices:
> 
>  ath10k_pci 0000:04:00.0: failed to flush transmit queue (skip 0 ar-state 1): 0
> 
> This is due to how the TX queues are flushed in ath10k. When a STA is
> removed, mac80211 need to flush queues [1], but because ath10k does not
> have a lightweight .flush_sta operation, ieee80211_flush_queues() is
> called instead effectively blocking the whole queue during the drain
> causing this radio silence. Also because ath10k_flush() waits for all
> queued to be emptied, not only the flushed ones it could more easily
> take up to 5 seconds to finish making the whole situation worst.
> 
> The first patch of this series adds a .flush_sta operation to flush only
> specific STA traffic avoiding the need to stop whole queues and should
> be enough in itself to fix the reported issue.
> 
> The second patch of this series is a proposal to improve ath10k_flush so
> that it will be less likely to timeout waiting for non related queues to
> drain.
> 
> The abose kernel warning could still be observed (e.g. flushing a dead
> STA) but should be now harmless.
> 
> [0]: https://lore.kernel.org/all/CA+Xfe4FjUmzM5mvPxGbpJsF3SvSdE5_wgxvgFJ0bsdrKODVXCQ@mail.gmail.com/
> [1]: commit 0b75a1b1e42e ("wifi: mac80211: flush queues on STA removal")
> 
> Remi Pommarel (2):
>   wifi: ath10k: Implement ieee80211 flush_sta callback
>   wifi: ath10k: Flush only requested txq in ath10k_flush()
> 
>  drivers/net/wireless/ath/ath10k/core.h   |  4 ++
>  drivers/net/wireless/ath/ath10k/htt.h    | 11 +++-
>  drivers/net/wireless/ath/ath10k/htt_tx.c | 50 +++++++++++++++-
>  drivers/net/wireless/ath/ath10k/mac.c    | 76 ++++++++++++++++++++----
>  drivers/net/wireless/ath/ath10k/txrx.c   |  5 +-
>  5 files changed, 129 insertions(+), 17 deletions(-)
> 
LGTM wit a few nits.
Hope the Qualcomm ath10k folks review this.

/jeff