[PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure

[Michal Kazior]

On 2 December 2016 at 03:29,  <greearb at candelatech.com> wrote:
> From: Ben Greear <greearb at candelatech.com>
>
> This appears to fix a problem where ath10k firmware would crash,
> mac80211 would start re-adding interfaces to the driver, but the
> iterate-active-interfaces logic would then try to use the half-built
> interfaces.  With a bit of extra debug to catch the problem, the
> ath10k crash looks like this:
>
> ath10k_pci 0000:05:00.0: Initializing arvif: ffff8801ce97e320 on vif: ffff8801ce97e1d8
>
> [the print that happens after arvif->ar is assigned is not shown, so code did not make it that far before
>  the tx-beacon-nowait method was called]
>
> tx-beacon-nowait:  arvif: ffff8801ce97e320  ar:           (null)
[...]
>
> Signed-off-by: Ben Greear <greearb at candelatech.com>
> ---
>  net/mac80211/util.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/mac80211/util.c b/net/mac80211/util.c
> index 863f2c1..abe1f64 100644
> --- a/net/mac80211/util.c
> +++ b/net/mac80211/util.c
> @@ -705,7 +705,7 @@ static void __iterate_interfaces(struct ieee80211_local *local,
>                         break;
>                 }
>                 if (!(iter_flags & IEEE80211_IFACE_ITER_RESUME_ALL) &&
> -                   active_only && !(sdata->flags & IEEE80211_SDATA_IN_DRIVER))
> +                   (active_only && (local->in_reconfig || !(sdata->flags & IEEE80211_SDATA_IN_DRIVER))))
>                         continue;

Doesn't this effectivelly prevent you from iterating over interfaces
completely during reconfig? As you bring up interfaces you might
need/want to iterate over others to re-adjust your own state.

I'd argue there should be another flag, IEEE80211_SDATA_RESUMING, used
with sdata->flags for resuming so that once it is re-added to the
driver it can be cleared (and therefore properly iterated over).


Michał