[PATCH] mac802154: Keep track of the channel when changed

[PATCH] mac802154: Keep track of the channel when changed

[Alan Ott]

Prevent set_channel() from getting called every time a packet is sent. This
looks like it was an oversight.

Signed-off-by: Alan Ott <alan@signal11.us>
---
 net/mac802154/tx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/mac802154/tx.c b/net/mac802154/tx.c
index 3fd3e07..6d16473 100644
--- a/net/mac802154/tx.c
+++ b/net/mac802154/tx.c
@@ -58,6 +58,9 @@ static void mac802154_xmit_worker(struct work_struct *work)
 			pr_debug("set_channel failed\n");
 			goto out;
 		}
+
+		xw->priv->phy->current_channel = xw->chan;
+		xw->priv->phy->current_page = xw->page;
 	}
 
 	res = xw->priv->ops->xmit(&xw->priv->hw, xw->skb);
-- 
1.7.11.2

Re: [Linux-zigbee-devel] [PATCH] mac802154: Keep track of the channel when changed

[Werner Almesberger]

Alan Ott wrote:
> Prevent set_channel() from getting called every time a packet is sent. This
> looks like it was an oversight.

at86rf230.c and derivatives avoid this problem by setting
phy->current_* in the *_channel function.

But I'd agree that it's nicer to do this in one place, not in
every driver.

In case a driver had a weird failure mode in which it leaves the
original channel but only makes it halfway to the new channel, it
could still set phy->current_* and return an error. So there's no
loss of functionality with your change.

- Werner

Re: [PATCH] mac802154: Keep track of the channel when changed

[Alan Ott]

On 04/05/2013 05:05 PM, Werner Almesberger wrote:
> Alan Ott wrote:
>> Prevent set_channel() from getting called every time a packet is sent. This
>> looks like it was an oversight.
> at86rf230.c and derivatives avoid this problem by setting
> phy->current_* in the *_channel function.
>
> But I'd agree that it's nicer to do this in one place, not in
> every driver.
>
> In case a driver had a weird failure mode in which it leaves the
> original channel but only makes it halfway to the new channel, it
> could still set phy->current_* and return an error. So there's no
> loss of functionality with your change.

Hmm... I just noticed that mib.c does the same thing (and doesn't set
phy->current_*). I'll need to fix that one too (and resubmit). :(

Alan.




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[PATCH v2] mac802154: Keep track of the channel when changed

[Alan Ott]

Two sections checked whether the current channel != the new channel
without ever setting the current channel variables.

1. net/mac802154/tx.c: Prevent set_channel() from getting called every
time a packet is sent.

2. net/mac802154/mib.c: Lock (pib_lock) accesses to current_channel and
current_page and make sure they are updated when the channel has been
changed.

Signed-off-by: Alan Ott <alan-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org>
---
 net/mac802154/mib.c | 12 +++++++++++-
 net/mac802154/tx.c  |  3 +++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/net/mac802154/mib.c b/net/mac802154/mib.c
index f03e55f..8ded97c 100644
--- a/net/mac802154/mib.c
+++ b/net/mac802154/mib.c
@@ -176,9 +176,15 @@ static void phy_chan_notify(struct work_struct *work)
 	struct mac802154_sub_if_data *priv = netdev_priv(nw->dev);
 	int res;
 
+	mutex_lock(&priv->hw->phy->pib_lock);
 	res = hw->ops->set_channel(&hw->hw, priv->page, priv->chan);
 	if (res)
 		pr_debug("set_channel failed\n");
+	else {
+		priv->hw->phy->current_channel = priv->chan;
+		priv->hw->phy->current_page = priv->page;
+	}
+	mutex_unlock(&priv->hw->phy->pib_lock);
 
 	kfree(nw);
 }
@@ -195,8 +201,11 @@ void mac802154_dev_set_page_channel(struct net_device *dev, u8 page, u8 chan)
 	priv->chan = chan;
 	spin_unlock_bh(&priv->mib_lock);
 
+	mutex_lock(&priv->hw->phy->pib_lock);
 	if (priv->hw->phy->current_channel != priv->chan ||
 	    priv->hw->phy->current_page != priv->page) {
+		mutex_unlock(&priv->hw->phy->pib_lock);
+
 		work = kzalloc(sizeof(*work), GFP_ATOMIC);
 		if (!work)
 			return;
@@ -204,5 +213,6 @@ void mac802154_dev_set_page_channel(struct net_device *dev, u8 page, u8 chan)
 		INIT_WORK(&work->work, phy_chan_notify);
 		work->dev = dev;
 		queue_work(priv->hw->dev_workqueue, &work->work);
-	}
+	} else
+		mutex_unlock(&priv->hw->phy->pib_lock);
 }
diff --git a/net/mac802154/tx.c b/net/mac802154/tx.c
index 3fd3e07..6d16473 100644
--- a/net/mac802154/tx.c
+++ b/net/mac802154/tx.c
@@ -58,6 +58,9 @@ static void mac802154_xmit_worker(struct work_struct *work)
 			pr_debug("set_channel failed\n");
 			goto out;
 		}
+
+		xw->priv->phy->current_channel = xw->chan;
+		xw->priv->phy->current_page = xw->page;
 	}
 
 	res = xw->priv->ops->xmit(&xw->priv->hw, xw->skb);
-- 
1.7.11.2


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Re: [PATCH v2] mac802154: Keep track of the channel when changed

[David Miller]

From: Alan Ott <alan@signal11.us>
Date: Fri,  5 Apr 2013 19:03:10 -0400

> Two sections checked whether the current channel != the new channel
> without ever setting the current channel variables.
> 
> 1. net/mac802154/tx.c: Prevent set_channel() from getting called every
> time a packet is sent.
> 
> 2. net/mac802154/mib.c: Lock (pib_lock) accesses to current_channel and
> current_page and make sure they are updated when the channel has been
> changed.
> 
> Signed-off-by: Alan Ott <alan@signal11.us>

Applied.