iwlwifi: use GFP_KERNEL to allocate Rx SKB memory

Previously we allocate Rx SKB with GFP_ATOMIC flag. This is because we need
to hold a spinlock to protect the two rx_used and rx_free lists operation
in the rxq.

	spin_lock();
	...
	element = rxq->rx_used.next;
	element->skb = alloc_skb(..., GFP_ATOMIC);
	list_del(element);
	list_add_tail(&element->list, &rxq->rx_free);
	...
	spin_unlock();

After spliting the rx_used delete and rx_free insert into two operations,
we don't require the skb allocation in an atomic context any more (the
function itself is scheduled in a workqueue).

	spin_lock();
	...
	element = rxq->rx_used.next;
	list_del(element);
	...
	spin_unlock();
	...
	element->skb = alloc_skb(..., GFP_KERNEL);
	...
	spin_lock()
	...
	list_add_tail(&element->list, &rxq->rx_free);
	...
	spin_unlock();

This patch should fix the "iwlagn: Can not allocate SKB buffers" warning
we see recently.

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Cc: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 19 insertions, 10 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-rx.c b/drivers/net/wireless/iwlwifi/iwl-rx.c
index 919a775121e4..c5f1aa0feac8 100644
--- a/drivers/net/wireless/iwlwifi/iwl-rx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-rx.c
@@ -244,25 +244,31 @@ void iwl_rx_allocate(struct iwl_priv *priv)
         struct list_head *element;
         struct iwl_rx_mem_buffer *rxb;
         unsigned long flags;
-        spin_lock_irqsave(&rxq->lock, flags);
-        while (!list_empty(&rxq->rx_used)) {
+
+        while (1) {
+                spin_lock_irqsave(&rxq->lock, flags);
+
+                if (list_empty(&rxq->rx_used)) {
+                        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 + 256,
-                                __GFP_NOWARN | GFP_ATOMIC);
+                                     GFP_KERNEL);
                 if (!rxb->skb) {
-                        if (net_ratelimit())
-                                printk(KERN_CRIT DRV_NAME
-                                       ": Can not allocate SKB buffers\n");
+                        printk(KERN_CRIT DRV_NAME
+                                   "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;
                 }
-                priv->alloc_rxb_skb++;
-                list_del(element);
 
                 /* Get physical address of RB/SKB */
                 rxb->real_dma_addr = pci_map_single(
@@ -276,12 +282,15 @@ void iwl_rx_allocate(struct iwl_priv *priv)
                 rxb->aligned_dma_addr = ALIGN(rxb->real_dma_addr, 256);
                 skb_reserve(rxb->skb, rxb->aligned_dma_addr - rxb->real_dma_addr);
 
+                spin_lock_irqsave(&rxq->lock, flags);
+
                 list_add_tail(&rxb->list, &rxq->rx_free);
                 rxq->free_count++;
+                priv->alloc_rxb_skb++;
+
+                spin_unlock_irqrestore(&rxq->lock, flags);
         }
-        spin_unlock_irqrestore(&rxq->lock, flags);
 }
-EXPORT_SYMBOL(iwl_rx_allocate);
 
 void iwl_rx_replenish(struct iwl_priv *priv)
 {