iwlcore: Allow skb allocation from tasklet.

If RX queue becomes empty then we need to restock the queue from tasklet to prevent
ucode from starving. A caller to iwl_rx_allocate will decide if allocated buffer should
come from GFP_ATOMIC or GFP_KERNEL.

Signed-off-by: Mohamed Abbas <mohamed.abbas@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

4 files changed, 34 insertions, 10 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.c b/drivers/net/wireless/iwlwifi/iwl-agn.c
index fa24b019c62c..be1058bdc4c5 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.c
@@ -831,6 +831,7 @@ void iwl_rx_handle(struct iwl_priv *priv)
         unsigned long flags;
         u8 fill_rx = 0;
         u32 count = 8;
+        int total_empty;
 
         /* uCode's read index (stored in shared DRAM) indicates the last Rx
          * buffer that the driver may process (last buffer filled by ucode). */
@@ -841,7 +842,12 @@ void iwl_rx_handle(struct iwl_priv *priv)
         if (i == r)
                 IWL_DEBUG_RX(priv, "r = %d, i = %d\n", r, i);
 
-        if (iwl_rx_queue_space(rxq) > (RX_QUEUE_SIZE / 2))
+        /* calculate total frames need to be restock after handling RX */
+        total_empty = r - priv->rxq.write_actual;
+        if (total_empty < 0)
+                total_empty += RX_QUEUE_SIZE;
+
+        if (total_empty > (RX_QUEUE_SIZE / 2))
                 fill_rx = 1;
 
         while (i != r) {
@@ -918,7 +924,7 @@ void iwl_rx_handle(struct iwl_priv *priv)
                         count++;
                         if (count >= 8) {
                                 priv->rxq.read = i;
-                                iwl_rx_queue_restock(priv);
+                                iwl_rx_replenish_now(priv);
                                 count = 0;
                         }
                 }
@@ -926,7 +932,10 @@ void iwl_rx_handle(struct iwl_priv *priv)
 
         /* Backtrack one entry */
         priv->rxq.read = i;
-        iwl_rx_queue_restock(priv);
+        if (fill_rx)
+                iwl_rx_replenish_now(priv);
+        else
+                iwl_rx_queue_restock(priv);
 }
 
 /* call this function to flush any scheduled tasklet */
diff --git a/drivers/net/wireless/iwlwifi/iwl-core.h b/drivers/net/wireless/iwlwifi/iwl-core.h
index cbd87afbf9ae..87df1b767941 100644
--- a/drivers/net/wireless/iwlwifi/iwl-core.h
+++ b/drivers/net/wireless/iwlwifi/iwl-core.h
@@ -318,10 +318,11 @@ int iwl_rx_queue_update_write_ptr(struct iwl_priv *priv,
                                   struct iwl_rx_queue *q);
 void iwl_rx_queue_reset(struct iwl_priv *priv, struct iwl_rx_queue *rxq);
 void iwl_rx_replenish(struct iwl_priv *priv);
+void iwl_rx_replenish_now(struct iwl_priv *priv);
 int iwl_rx_init(struct iwl_priv *priv, struct iwl_rx_queue *rxq);
 int iwl_rx_queue_restock(struct iwl_priv *priv);
 int iwl_rx_queue_space(const struct iwl_rx_queue *q);
-void iwl_rx_allocate(struct iwl_priv *priv);
+void iwl_rx_allocate(struct iwl_priv *priv, gfp_t priority);
 void iwl_tx_cmd_complete(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb);
 int iwl_tx_queue_reclaim(struct iwl_priv *priv, int txq_id, int index);
 /* Handlers */
diff --git a/drivers/net/wireless/iwlwifi/iwl-dev.h b/drivers/net/wireless/iwlwifi/iwl-dev.h
index 2076742effdd..770cd1b062ff 100644
--- a/drivers/net/wireless/iwlwifi/iwl-dev.h
+++ b/drivers/net/wireless/iwlwifi/iwl-dev.h
@@ -382,6 +382,7 @@ struct iwl_rx_queue {
         u32 read;
         u32 write;
         u32 free_count;
+        u32 write_actual;
         struct list_head rx_free;
         struct list_head rx_used;
         int need_update;
diff --git a/drivers/net/wireless/iwlwifi/iwl-rx.c b/drivers/net/wireless/iwlwifi/iwl-rx.c
index 7a432829e79f..c845089701eb 100644
--- a/drivers/net/wireless/iwlwifi/iwl-rx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-rx.c
@@ -145,12 +145,14 @@ int iwl_rx_queue_update_write_ptr(struct iwl_priv *priv, struct iwl_rx_queue *q)
                         goto exit_unlock;
                 }
 
-                iwl_write_direct32(priv, rx_wrt_ptr_reg, q->write & ~0x7);
+                q->write_actual = (q->write & ~0x7);
+                iwl_write_direct32(priv, rx_wrt_ptr_reg, q->write_actual);
 
         /* Else device is assumed to be awake */
         } else {
                 /* Device expects a multiple of 8 */
-                iwl_write32(priv, rx_wrt_ptr_reg, q->write & ~0x7);
+                q->write_actual = (q->write & ~0x7);
+                iwl_write_direct32(priv, rx_wrt_ptr_reg, q->write_actual);
         }
 
         q->need_update = 0;
@@ -212,7 +214,7 @@ int iwl_rx_queue_restock(struct iwl_priv *priv)
 
         /* If we've added more space for the firmware to place data, tell it.
          * Increment device's write pointer in multiples of 8. */
-        if (write != (rxq->write & ~0x7)) {
+        if (rxq->write_actual != (rxq->write & ~0x7)) {
                 spin_lock_irqsave(&rxq->lock, flags);
                 rxq->need_update = 1;
                 spin_unlock_irqrestore(&rxq->lock, flags);
@@ -232,7 +234,7 @@ EXPORT_SYMBOL(iwl_rx_queue_restock);
  * Also restock the Rx queue via iwl_rx_queue_restock.
  * This is called as a scheduled work item (except for during initialization)
  */
-void iwl_rx_allocate(struct iwl_priv *priv)
+void iwl_rx_allocate(struct iwl_priv *priv, gfp_t priority)
 {
         struct iwl_rx_queue *rxq = &priv->rxq;
         struct list_head *element;
@@ -254,7 +256,8 @@ void iwl_rx_allocate(struct iwl_priv *priv)
 
                 /* Alloc a new receive buffer */
                 rxb->skb = alloc_skb(priv->hw_params.rx_buf_size + 256,
-                                     GFP_KERNEL);
+                                                priority);
+
                 if (!rxb->skb) {
                         IWL_CRIT(priv, "Can not allocate SKB buffers\n");
                         /* We don't reschedule replenish work here -- we will
@@ -289,7 +292,7 @@ void iwl_rx_replenish(struct iwl_priv *priv)
 {
         unsigned long flags;
 
-        iwl_rx_allocate(priv);
+        iwl_rx_allocate(priv, GFP_KERNEL);
 
         spin_lock_irqsave(&priv->lock, flags);
         iwl_rx_queue_restock(priv);
@@ -297,6 +300,14 @@ void iwl_rx_replenish(struct iwl_priv *priv)
 }
 EXPORT_SYMBOL(iwl_rx_replenish);
 
+void iwl_rx_replenish_now(struct iwl_priv *priv)
+{
+        iwl_rx_allocate(priv, GFP_ATOMIC);
+
+        iwl_rx_queue_restock(priv);
+}
+EXPORT_SYMBOL(iwl_rx_replenish_now);
+
 
 /* Assumes that the skb field of the buffers in 'pool' is kept accurate.
  * If an SKB has been detached, the POOL needs to have its SKB set to NULL
@@ -352,6 +363,7 @@ int iwl_rx_queue_alloc(struct iwl_priv *priv)
         /* Set us so that we have processed and used all buffers, but have
          * not restocked the Rx queue with fresh buffers */
         rxq->read = rxq->write = 0;
+        rxq->write_actual = 0;
         rxq->free_count = 0;
         rxq->need_update = 0;
         return 0;
@@ -390,6 +402,7 @@ void iwl_rx_queue_reset(struct iwl_priv *priv, struct iwl_rx_queue *rxq)
         /* Set us so that we have processed and used all buffers, but have
          * not restocked the Rx queue with fresh buffers */
         rxq->read = rxq->write = 0;
+        rxq->write_actual = 0;
         rxq->free_count = 0;
         spin_unlock_irqrestore(&rxq->lock, flags);
 }