Re: [PATCH v4 1/2] mac80211: Add support to trigger sta disconnect on hardware restart

[Jeff Johnson]

On 3/3/2022 3:55 AM, Youghandhar Chintala wrote:
> Currently in case of target hardware restart, we just reconfig and
> re-enable the security keys and enable the network queues to start
> data traffic back from where it was interrupted.
>
> Many ath10k wifi chipsets have sequence numbers for the data
> packets assigned by firmware and the mac sequence number will
> restart from zero after target hardware restart leading to mismatch
> in the sequence number expected by the remote peer vs the sequence
> number of the frame sent by the target firmware.
>
> This mismatch in sequence number will cause out-of-order packets
> on the remote peer and all the frames sent by the device are dropped
> until we reach the sequence number which was sent before we restarted
> the target hardware
>
> In order to fix this, we trigger a sta disconnect, in case of target
> hw restart. After this there will be a fresh connection and thereby
> avoiding the dropping of frames by remote peer.
>
> The right fix would be to pull the entire data path into the host
> which is not feasible or would need lots of complex changes and
> will still be inefficient.
>
> Tested on ath10k using WCN3990, QCA6174
>
> Signed-off-by: Youghandhar Chintala <youghand@xxxxxxxxxxxxxx>
> ---
>   include/net/mac80211.h     | 11 +++++++++++
>   net/mac80211/ieee80211_i.h |  3 +++
>   net/mac80211/mlme.c        | 12 ++++++++++++
>   net/mac80211/util.c        | 33 ++++++++++++++++++++++++++++++---
>   4 files changed, 56 insertions(+), 3 deletions(-)
>
> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
> index bd6912d0292b..0773c50fa182 100644
> --- a/include/net/mac80211.h
> +++ b/include/net/mac80211.h
> @@ -6064,6 +6064,17 @@ void ieee80211_disconnect(struct ieee80211_vif *vif, bool reconnect);
>    */
>   void ieee80211_resume_disconnect(struct ieee80211_vif *vif);
>   
> +/**
> + * ieee80211_hw_restart_disconnect - disconnect from AP after
> + * hardware  restart

nits:
remove excess space in "hardware  restart"

"Do not leave a blank line between the function description and the 
arguments" per 
<https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html#function-documentation>

(I see that there is quite a mixture of compliant and non-compliant 
kernel-doc in this file)