[PATCH v3] mac80211: stop Rx during HW reconfig

[PATCH v3] mac80211: stop Rx during HW reconfig

[Arik Nemtsov]

While HW reconfig is in progress, drop all incoming Rx. This prevents
incoming packets from changing the internal state of the driver or
calling callbacks of the low level driver while it is in inconsistent
state.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
---
 net/mac80211/ieee80211_i.h |    3 +++
 net/mac80211/main.c        |    7 +++++++
 net/mac80211/rx.c          |    4 ++++
 net/mac80211/util.c        |    3 +++
 4 files changed, 17 insertions(+)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index ae046b5..04e8912 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -912,6 +912,9 @@ struct ieee80211_local {
 	/* device is started */
 	bool started;
 
+	/* device is during a HW reconfig */
+	bool in_reconfig;
+
 	/* wowlan is enabled -- don't reconfig on resume */
 	bool wowlan;
 
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index b70f7f0..eb4a5b9 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -345,6 +345,13 @@ void ieee80211_restart_hw(struct ieee80211_hw *hw)
 	ieee80211_stop_queues_by_reason(hw,
 		IEEE80211_QUEUE_STOP_REASON_SUSPEND);
 
+	/*
+	 * Stop all Rx during the reconfig. We don't want state changes
+	 * or driver callbacks while this is in progress.
+	 */
+	local->in_reconfig = true;
+	barrier();
+
 	schedule_work(&local->restart_work);
 }
 EXPORT_SYMBOL(ieee80211_restart_hw);
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index d5ac02f..3b488e3 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -3033,6 +3033,10 @@ void ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb)
 	if (unlikely(local->quiescing || local->suspended))
 		goto drop;
 
+	/* We might be during a HW reconfig, prevent Rx for the same reason */
+	if (unlikely(local->in_reconfig))
+		goto drop;
+
 	/*
 	 * The same happens when we're not even started,
 	 * but that's worth a warning.
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 76f90c1..ee46273 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1399,6 +1399,9 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 		if (ieee80211_sdata_running(sdata))
 			ieee80211_enable_keys(sdata);
 
+	local->in_reconfig = false;
+	barrier();
+
  wake_up:
 	/*
 	 * Clear the WLAN_STA_BLOCK_BA flag so new aggregation
-- 
1.7.9.5

Re: [PATCH v3] mac80211: stop Rx during HW reconfig

[John W. Linville]

Should this go to 3.5 and/or stable?

On Wed, Jun 06, 2012 at 11:25:02AM +0300, Arik Nemtsov wrote:
> While HW reconfig is in progress, drop all incoming Rx. This prevents
> incoming packets from changing the internal state of the driver or
> calling callbacks of the low level driver while it is in inconsistent
> state.
> 
> Signed-off-by: Arik Nemtsov <arik@wizery.com>
> ---
>  net/mac80211/ieee80211_i.h |    3 +++
>  net/mac80211/main.c        |    7 +++++++
>  net/mac80211/rx.c          |    4 ++++
>  net/mac80211/util.c        |    3 +++
>  4 files changed, 17 insertions(+)
> 
> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index ae046b5..04e8912 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -912,6 +912,9 @@ struct ieee80211_local {
>  	/* device is started */
>  	bool started;
>  
> +	/* device is during a HW reconfig */
> +	bool in_reconfig;
> +
>  	/* wowlan is enabled -- don't reconfig on resume */
>  	bool wowlan;
>  
> diff --git a/net/mac80211/main.c b/net/mac80211/main.c
> index b70f7f0..eb4a5b9 100644
> --- a/net/mac80211/main.c
> +++ b/net/mac80211/main.c
> @@ -345,6 +345,13 @@ void ieee80211_restart_hw(struct ieee80211_hw *hw)
>  	ieee80211_stop_queues_by_reason(hw,
>  		IEEE80211_QUEUE_STOP_REASON_SUSPEND);
>  
> +	/*
> +	 * Stop all Rx during the reconfig. We don't want state changes
> +	 * or driver callbacks while this is in progress.
> +	 */
> +	local->in_reconfig = true;
> +	barrier();
> +
>  	schedule_work(&local->restart_work);
>  }
>  EXPORT_SYMBOL(ieee80211_restart_hw);
> diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
> index d5ac02f..3b488e3 100644
> --- a/net/mac80211/rx.c
> +++ b/net/mac80211/rx.c
> @@ -3033,6 +3033,10 @@ void ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb)
>  	if (unlikely(local->quiescing || local->suspended))
>  		goto drop;
>  
> +	/* We might be during a HW reconfig, prevent Rx for the same reason */
> +	if (unlikely(local->in_reconfig))
> +		goto drop;
> +
>  	/*
>  	 * The same happens when we're not even started,
>  	 * but that's worth a warning.
> diff --git a/net/mac80211/util.c b/net/mac80211/util.c
> index 76f90c1..ee46273 100644
> --- a/net/mac80211/util.c
> +++ b/net/mac80211/util.c
> @@ -1399,6 +1399,9 @@ int ieee80211_reconfig(struct ieee80211_local *local)
>  		if (ieee80211_sdata_running(sdata))
>  			ieee80211_enable_keys(sdata);
>  
> +	local->in_reconfig = false;
> +	barrier();
> +
>   wake_up:
>  	/*
>  	 * Clear the WLAN_STA_BLOCK_BA flag so new aggregation
> -- 
> 1.7.9.5
> 
> --
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> 

-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.

Re: [PATCH v3] mac80211: stop Rx during HW reconfig

[Arik Nemtsov]

On Fri, Jun 8, 2012 at 8:39 PM, John W. Linville <linville@tuxdriver.com> wrote:
> Should this go to 3.5 and/or stable?

I don't think this is necessary. This only partially solves the race,
and reconfig is a corner case anyway.

And the part of the race it solves is actually only created in 3.6, by
the patch "mac80211: add stations after AP start on reconfig".

Arik

Re: [PATCH v3] mac80211: stop Rx during HW reconfig

[Arik Nemtsov]

On Wed, Jun 6, 2012 at 11:25 AM, Arik Nemtsov <arik@wizery.com> wrote:
> While HW reconfig is in progress, drop all incoming Rx. This prevents
> incoming packets from changing the internal state of the driver or
> calling callbacks of the low level driver while it is in inconsistent
> state.
>

Ping?

Re: [PATCH v3] mac80211: stop Rx during HW reconfig

[Johannes Berg]

On Wed, 2012-06-06 at 11:25 +0300, Arik Nemtsov wrote:
> While HW reconfig is in progress, drop all incoming Rx. This prevents
> incoming packets from changing the internal state of the driver or
> calling callbacks of the low level driver while it is in inconsistent
> state.

Applied.

johannes