Re: [PATCH] p54: Fix regression in 2.6.31-rcX since commit a1091aa- sleeping function called from invalid context

[Larry Finger]

David Miller wrote:
> From: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
> Date: Mon, 06 Jul 2009 14:43:45 -0500
> 
>> I'm available for testing.
> 
> I just committed the following to my net-2.6 tree, give
> it a spin:
> 
>>From 0ca1b08eba627b4245efd0f71b55a062bf163777 Mon Sep 17 00:00:00 2001
> From: David S. Miller <davem@xxxxxxxxxxxxx>
> Date: Mon, 6 Jul 2009 12:49:18 -0700
> Subject: [PATCH] Revert "p54: Use SKB list handling helpers instead of by-hand code."
> 
> This reverts commit a1091aae19b1d9c85d91c86915a611387f67a26b.
> ---
>  drivers/net/wireless/p54/p54common.c |   46 ++++++++++++++++++++--------------
>  1 files changed, 27 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/net/wireless/p54/p54common.c b/drivers/net/wireless/p54/p54common.c
> index b618bd1..48d81d9 100644
> --- a/drivers/net/wireless/p54/p54common.c
> +++ b/drivers/net/wireless/p54/p54common.c
> @@ -823,30 +823,30 @@ void p54_free_skb(struct ieee80211_hw *dev, struct sk_buff *skb)
>  	struct p54_tx_info *range;
>  	unsigned long flags;
>  
> -	if (unlikely(!skb || !dev || skb_queue_empty(&priv->tx_queue)))
> +	if (unlikely(!skb || !dev || !skb_queue_len(&priv->tx_queue)))
>  		return;
>  
> -	/* There used to be a check here to see if the SKB was on the
> -	 * TX queue or not.  This can never happen because all SKBs we
> -	 * see here successfully went through p54_assign_address()
> -	 * which means the SKB is on the ->tx_queue.
> +	/*
> +	 * don't try to free an already unlinked skb
>  	 */
> +	if (unlikely((!skb->next) || (!skb->prev)))
> +		return;
>  
>  	spin_lock_irqsave(&priv->tx_queue.lock, flags);
>  	info = IEEE80211_SKB_CB(skb);
>  	range = (void *)info->rate_driver_data;
> -	if (!skb_queue_is_first(&priv->tx_queue, skb)) {
> +	if (skb->prev != (struct sk_buff *)&priv->tx_queue) {
>  		struct ieee80211_tx_info *ni;
>  		struct p54_tx_info *mr;
>  
> -		ni = IEEE80211_SKB_CB(skb_queue_prev(&priv->tx_queue, skb));
> +		ni = IEEE80211_SKB_CB(skb->prev);
>  		mr = (struct p54_tx_info *)ni->rate_driver_data;
>  	}
> -	if (!skb_queue_is_last(&priv->tx_queue, skb)) {
> +	if (skb->next != (struct sk_buff *)&priv->tx_queue) {
>  		struct ieee80211_tx_info *ni;
>  		struct p54_tx_info *mr;
>  
> -		ni = IEEE80211_SKB_CB(skb_queue_next(&priv->tx_queue, skb));
> +		ni = IEEE80211_SKB_CB(skb->next);
>  		mr = (struct p54_tx_info *)ni->rate_driver_data;
>  	}
>  	__skb_unlink(skb, &priv->tx_queue);
> @@ -864,13 +864,15 @@ static struct sk_buff *p54_find_tx_entry(struct ieee80211_hw *dev,
>  	unsigned long flags;
>  
>  	spin_lock_irqsave(&priv->tx_queue.lock, flags);
> -	skb_queue_walk(&priv->tx_queue, entry) {
> +	entry = priv->tx_queue.next;
> +	while (entry != (struct sk_buff *)&priv->tx_queue) {
>  		struct p54_hdr *hdr = (struct p54_hdr *) entry->data;
>  
>  		if (hdr->req_id == req_id) {
>  			spin_unlock_irqrestore(&priv->tx_queue.lock, flags);
>  			return entry;
>  		}
> +		entry = entry->next;
>  	}
>  	spin_unlock_irqrestore(&priv->tx_queue.lock, flags);
>  	return NULL;
> @@ -888,22 +890,24 @@ static void p54_rx_frame_sent(struct ieee80211_hw *dev, struct sk_buff *skb)
>  	int count, idx;
>  
>  	spin_lock_irqsave(&priv->tx_queue.lock, flags);
> -	skb_queue_walk(&priv->tx_queue, entry) {
> +	entry = (struct sk_buff *) priv->tx_queue.next;
> +	while (entry != (struct sk_buff *)&priv->tx_queue) {
>  		struct ieee80211_tx_info *info = IEEE80211_SKB_CB(entry);
>  		struct p54_hdr *entry_hdr;
>  		struct p54_tx_data *entry_data;
>  		unsigned int pad = 0, frame_len;
>  
>  		range = (void *)info->rate_driver_data;
> -		if (range->start_addr != addr)
> +		if (range->start_addr != addr) {
> +			entry = entry->next;
>  			continue;
> +		}
>  
> -		if (!skb_queue_is_last(&priv->tx_queue, entry)) {
> +		if (entry->next != (struct sk_buff *)&priv->tx_queue) {
>  			struct ieee80211_tx_info *ni;
>  			struct p54_tx_info *mr;
>  
> -			ni = IEEE80211_SKB_CB(skb_queue_next(&priv->tx_queue,
> -							     entry));
> +			ni = IEEE80211_SKB_CB(entry->next);
>  			mr = (struct p54_tx_info *)ni->rate_driver_data;
>  		}
>  
> @@ -1164,21 +1168,23 @@ static int p54_assign_address(struct ieee80211_hw *dev, struct sk_buff *skb,
>  		}
>  	}
>  
> -	skb_queue_walk(&priv->tx_queue, entry) {
> +	entry = priv->tx_queue.next;
> +	while (left--) {
>  		u32 hole_size;
>  		info = IEEE80211_SKB_CB(entry);
>  		range = (void *)info->rate_driver_data;
>  		hole_size = range->start_addr - last_addr;
>  		if (!target_skb && hole_size >= len) {
> -			target_skb = skb_queue_prev(&priv->tx_queue, entry);
> +			target_skb = entry->prev;
>  			hole_size -= len;
>  			target_addr = last_addr;
>  		}
>  		largest_hole = max(largest_hole, hole_size);
>  		last_addr = range->end_addr;
> +		entry = entry->next;
>  	}
>  	if (!target_skb && priv->rx_end - last_addr >= len) {
> -		target_skb = skb_peek_tail(&priv->tx_queue);
> +		target_skb = priv->tx_queue.prev;
>  		largest_hole = max(largest_hole, priv->rx_end - last_addr - len);
>  		if (!skb_queue_empty(&priv->tx_queue)) {
>  			info = IEEE80211_SKB_CB(target_skb);
> @@ -2084,6 +2090,7 @@ out:
>  static void p54_stop(struct ieee80211_hw *dev)
>  {
>  	struct p54_common *priv = dev->priv;
> +	struct sk_buff *skb;
>  
>  	mutex_lock(&priv->conf_mutex);
>  	priv->mode = NL80211_IFTYPE_UNSPECIFIED;
> @@ -2098,7 +2105,8 @@ static void p54_stop(struct ieee80211_hw *dev)
>  		p54_tx_cancel(dev, priv->cached_beacon);
>  
>  	priv->stop(dev);
> -	skb_queue_purge(&priv->tx_queue);
> +	while ((skb = skb_dequeue(&priv->tx_queue)))
> +		kfree_skb(skb);
>  	priv->cached_beacon = NULL;
>  	priv->tsf_high32 = priv->tsf_low32 = 0;
>  	mutex_unlock(&priv->conf_mutex);

This patch fixes my USB device.

Please push to Linus.

Thanks,

Larry

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