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ath10k: workaround fw beaconing bug

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Some firmware revisions don't wait for beacon tx
completion before sending another SWBA event. This
could lead to hardware using old (freed) beacon
data in some cases, e.g. tx credit starvation
combined with missed TBTT. This is very very rare.

On non-IOMMU-enabled hosts this could be a
possible security issue because hw could beacon
some random data on the air.  On IOMMU-enabled
hosts DMAR faults would occur in most cases and
target device would crash.

Since there are no beacon tx completions (implicit
nor explicit) propagated to host the only
workaround for this is to allocate a DMA-coherent
buffer for a lifetime of a vif and use it for all
beacon tx commands. Worst case for this approach
is some beacons may become corrupted, e.g. garbled
IEs or out-of-date TIM bitmap.

Keep the original beacon-related code as-is in
case future firmware revisions solve this problem
so that the old path can be easily re-enabled with
a fw_feature flag.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
This commit is contained in:
Michal Kazior
2014-09-18 11:18:02 +03:00
committed by Kalle Valo
parent b25f32cb02
commit 64badcb6d6
4 changed files with 102 additions and 43 deletions
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1
drivers/net/wireless/ath/ath10k/mac.h
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@@ -39,6 +39,7 @@ void ath10k_offchan_tx_work(struct work_struct *work);
void ath10k_mgmt_over_wmi_tx_purge(struct ath10k *ar);
void ath10k_mgmt_over_wmi_tx_work(struct work_struct *work);
void ath10k_halt(struct ath10k *ar);
void ath10k_mac_vif_beacon_free(struct ath10k_vif *arvif);
static inline struct ath10k_vif *ath10k_vif_to_arvif(struct ieee80211_vif *vif)
{