2021-10-25 14:14:36

by P Praneesh

Subject: [PATCH v2] ath11k: Increment pending_mgmt_tx count before tx send invoke

There is a race condition whereby the tx completion handler can be invoked
before the 'num_pending_mgmt_tx" count is incremented. If that occurs, we
could get warning trace indicating that 'num_pending_mgmt_tx' is 0 (because
it was not yet incremented). Ideally, this trace should be seen only if
mgmt tx has not happened but tx completion is received, and it is not
expected in this race condition.

Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.4.0.1-01386-QCAHKSWPL_SILICONZ-1

Co-developed-by: Lavanya Suresh <[email protected]>
Signed-off-by: Lavanya Suresh <[email protected]>
Signed-off-by: P Praneesh <[email protected]>
---
v2: - corrected signed off detail.
---
drivers/net/wireless/ath/ath11k/mac.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
index 1cc5560..56f3208 100644
--- a/drivers/net/wireless/ath/ath11k/mac.c
+++ b/drivers/net/wireless/ath/ath11k/mac.c
@@ -5048,13 +5048,15 @@ static void ath11k_mgmt_over_wmi_tx_work(struct work_struct *work)
arvif = ath11k_vif_to_arvif(skb_cb->vif);
if (ar->allocated_vdev_map & (1LL << arvif->vdev_id) &&
arvif->is_started) {
+ atomic_inc(&ar->num_pending_mgmt_tx);
ret = ath11k_mac_mgmt_tx_wmi(ar, arvif, skb);
if (ret) {
+ if (atomic_dec_if_positive(&ar->num_pending_mgmt_tx) < 0)
+ WARN_ON_ONCE(1);
+
ath11k_warn(ar->ab, "failed to tx mgmt frame, vdev_id %d :%d\n",
arvif->vdev_id, ret);
ieee80211_free_txskb(ar->hw, skb);
- } else {
- atomic_inc(&ar->num_pending_mgmt_tx);
}
} else {
ath11k_warn(ar->ab,
--
2.7.4

2021-11-15 09:26:54

by Kalle Valo

Subject: Re: [PATCH v2] ath11k: Increment pending_mgmt_tx count before tx send invoke

P Praneesh <[email protected]> wrote:

> There is a race condition whereby the tx completion handler can be invoked
> before the 'num_pending_mgmt_tx" count is incremented. If that occurs, we
> could get warning trace indicating that 'num_pending_mgmt_tx' is 0 (because
> it was not yet incremented). Ideally, this trace should be seen only if
> mgmt tx has not happened but tx completion is received, and it is not
> expected in this race condition.
>
> Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.4.0.1-01386-QCAHKSWPL_SILICONZ-1
>
> Co-developed-by: Lavanya Suresh <[email protected]>
> Signed-off-by: Lavanya Suresh <[email protected]>
> Signed-off-by: P Praneesh <[email protected]>
> Signed-off-by: Kalle Valo <[email protected]>

Patch applied to ath-next branch of ath.git, thanks.

c0b0d2e87d91 ath11k: Increment pending_mgmt_tx count before tx send invoke

--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches