From de0bd50845eb5935ce3d503c5d2f565d6cb9ece1 Mon Sep 17 00:00:00 2001 From: Reinette Chatre Date: Fri, 11 Sep 2009 10:38:12 -0700 Subject: [PATCH] iwlwifi: fix potential rx buffer loss RX handling maintains a few lists that keep track of the RX buffers. Buffers move from one list to the other as they are used, replenished, and again made available for usage. In one such instance, when a buffer is used it enters the "rx_used" list. When buffers are replenished an skb is attached to the buffer and it is moved to the "rx_free" list. The problem here is that the buffer is first removed from the "rx_used" list _before_ the skb is allocated. Thus, if the skb allocation fails this buffer remains removed from the "rx_used" list and is thus lost for future usage. Fix this by first allocating the skb before trying to attach it to a list. We add an additional check to not do this unnecessarily. Reported-by: Rick Farrington Signed-off-by: Reinette Chatre Signed-off-by: John W. Linville --- drivers/net/wireless/iwlwifi/iwl-rx.c | 34 +++++++++++++-------- drivers/net/wireless/iwlwifi/iwl3945-base.c | 24 ++++++++++----- 2 files changed, 38 insertions(+), 20 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-rx.c b/drivers/net/wireless/iwlwifi/iwl-rx.c index 8150c5c3a16b..b90adcb73b06 100644 --- a/drivers/net/wireless/iwlwifi/iwl-rx.c +++ b/drivers/net/wireless/iwlwifi/iwl-rx.c @@ -239,13 +239,34 @@ void iwl_rx_allocate(struct iwl_priv *priv, gfp_t priority) struct iwl_rx_queue *rxq = &priv->rxq; struct list_head *element; struct iwl_rx_mem_buffer *rxb; + struct sk_buff *skb; unsigned long flags; while (1) { + spin_lock_irqsave(&rxq->lock, flags); + if (list_empty(&rxq->rx_used)) { + spin_unlock_irqrestore(&rxq->lock, flags); + return; + } + spin_unlock_irqrestore(&rxq->lock, flags); + + /* Alloc a new receive buffer */ + skb = alloc_skb(priv->hw_params.rx_buf_size + 256, + priority); + + if (!skb) { + IWL_CRIT(priv, "Can not allocate SKB buffers\n"); + /* We don't reschedule replenish work here -- we will + * call the restock method and if it still needs + * more buffers it will schedule replenish */ + break; + } + spin_lock_irqsave(&rxq->lock, flags); if (list_empty(&rxq->rx_used)) { spin_unlock_irqrestore(&rxq->lock, flags); + dev_kfree_skb_any(skb); return; } element = rxq->rx_used.next; @@ -254,18 +275,7 @@ void iwl_rx_allocate(struct iwl_priv *priv, gfp_t priority) spin_unlock_irqrestore(&rxq->lock, flags); - /* Alloc a new receive buffer */ - rxb->skb = alloc_skb(priv->hw_params.rx_buf_size + 256, - priority); - - if (!rxb->skb) { - IWL_CRIT(priv, "Can not allocate SKB buffers\n"); - /* We don't reschedule replenish work here -- we will - * call the restock method and if it still needs - * more buffers it will schedule replenish */ - break; - } - + rxb->skb = skb; /* Get physical address of RB/SKB */ rxb->real_dma_addr = pci_map_single( priv->pci_dev, diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c index 2238c9f2018c..090966837f3c 100644 --- a/drivers/net/wireless/iwlwifi/iwl3945-base.c +++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c @@ -1134,6 +1134,7 @@ static void iwl3945_rx_allocate(struct iwl_priv *priv, gfp_t priority) struct iwl_rx_queue *rxq = &priv->rxq; struct list_head *element; struct iwl_rx_mem_buffer *rxb; + struct sk_buff *skb; unsigned long flags; while (1) { @@ -1143,17 +1144,11 @@ static void iwl3945_rx_allocate(struct iwl_priv *priv, gfp_t priority) spin_unlock_irqrestore(&rxq->lock, flags); return; } - - element = rxq->rx_used.next; - rxb = list_entry(element, struct iwl_rx_mem_buffer, list); - list_del(element); spin_unlock_irqrestore(&rxq->lock, flags); /* Alloc a new receive buffer */ - rxb->skb = - alloc_skb(priv->hw_params.rx_buf_size, - priority); - if (!rxb->skb) { + skb = alloc_skb(priv->hw_params.rx_buf_size, priority); + if (!skb) { if (net_ratelimit()) IWL_CRIT(priv, ": Can not allocate SKB buffers\n"); /* We don't reschedule replenish work here -- we will @@ -1162,6 +1157,19 @@ static void iwl3945_rx_allocate(struct iwl_priv *priv, gfp_t priority) break; } + spin_lock_irqsave(&rxq->lock, flags); + if (list_empty(&rxq->rx_used)) { + spin_unlock_irqrestore(&rxq->lock, flags); + dev_kfree_skb_any(skb); + return; + } + element = rxq->rx_used.next; + rxb = list_entry(element, struct iwl_rx_mem_buffer, list); + list_del(element); + spin_unlock_irqrestore(&rxq->lock, flags); + + rxb->skb = skb; + /* If radiotap head is required, reserve some headroom here. * The physical head count is a variable rx_stats->phy_count. * We reserve 4 bytes here. Plus these extra bytes, the