iwlegacy: fix enqueue hcmd race conditions

We mark command as huge by using meta->flags from other (non huge) command,
but flags can be possibly overridden, when non huge command is enqueued,
what can lead to:

WARNING: at lib/dma-debug.c:696 dma_debug_device_change+0x1a3/0x1f0()
DMA-API: device driver has pending DMA allocations while released from device [count=1]

To fix introduce additional CMD_MAPPED to mark command as mapped and
serialize iwl_enqueue_hcmd() with iwl_tx_cmd_complete() using
hcmd_lock. Serialization will also fix possible race conditions,
because q->read_ptr, q->write_ptr are modified/used in parallel.

Do not change callback, I did (and fixed) that mistake in iwlagn.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/iwlegacy/iwl-dev.h b/drivers/net/wireless/iwlegacy/iwl-dev.h
index 36c01aa3b7c27d3a0873b5d8befd521abc4c90f1..df19d5c69e7f065e035f2f2ff5e1036e419c1a59 100644 (file)
--- a/drivers/net/wireless/iwlegacy/iwl-dev.h
+++ b/drivers/net/wireless/iwlegacy/iwl-dev.h
@@ -290,6 +290,7 @@ enum {
        CMD_SIZE_HUGE = (1 << 0),
        CMD_ASYNC = (1 << 1),
        CMD_WANT_SKB = (1 << 2),
+       CMD_MAPPED = (1 << 3),
 };
 
 #define DEF_CMD_PAYLOAD_SIZE 320

diff --git a/drivers/net/wireless/iwlegacy/iwl-tx.c b/drivers/net/wireless/iwlegacy/iwl-tx.c
index a227773cb384443ac4e41c0f4db81a98b6dbaea9..4fff995c6f3e2f4cbb97139d52625fa5ccce2321 100644 (file)
--- a/drivers/net/wireless/iwlegacy/iwl-tx.c
+++ b/drivers/net/wireless/iwlegacy/iwl-tx.c
@@ -146,33 +146,32 @@ void iwl_legacy_cmd_queue_unmap(struct iwl_priv *priv)
 {
        struct iwl_tx_queue *txq = &priv->txq[priv->cmd_queue];
        struct iwl_queue *q = &txq->q;
-       bool huge = false;
        int i;
 
        if (q->n_bd == 0)
                return;
 
        while (q->read_ptr != q->write_ptr) {
-               /* we have no way to tell if it is a huge cmd ATM */
                i = iwl_legacy_get_cmd_index(q, q->read_ptr, 0);
 
-               if (txq->meta[i].flags & CMD_SIZE_HUGE)
-                       huge = true;
-               else
+               if (txq->meta[i].flags & CMD_MAPPED) {
                        pci_unmap_single(priv->pci_dev,
                                         dma_unmap_addr(&txq->meta[i], mapping),
                                         dma_unmap_len(&txq->meta[i], len),
                                         PCI_DMA_BIDIRECTIONAL);
+                       txq->meta[i].flags = 0;
+               }
 
                q->read_ptr = iwl_legacy_queue_inc_wrap(q->read_ptr, q->n_bd);
        }
 
-       if (huge) {
-               i = q->n_window;
+       i = q->n_window;
+       if (txq->meta[i].flags & CMD_MAPPED) {
                pci_unmap_single(priv->pci_dev,
                                 dma_unmap_addr(&txq->meta[i], mapping),
                                 dma_unmap_len(&txq->meta[i], len),
                                 PCI_DMA_BIDIRECTIONAL);
+               txq->meta[i].flags = 0;
        }
 }
 EXPORT_SYMBOL(iwl_legacy_cmd_queue_unmap);
@@ -467,29 +466,27 @@ int iwl_legacy_enqueue_hcmd(struct iwl_priv *priv, struct iwl_host_cmd *cmd)
                return -EIO;
        }
 
+       spin_lock_irqsave(&priv->hcmd_lock, flags);
+
        if (iwl_legacy_queue_space(q) < ((cmd->flags & CMD_ASYNC) ? 2 : 1)) {
-               IWL_ERR(priv, "No space in command queue\n");
-               IWL_ERR(priv, "Restarting adapter due to queue full\n");
+               spin_unlock_irqrestore(&priv->hcmd_lock, flags);
+
+               IWL_ERR(priv, "Restarting adapter due to command queue full\n");
                queue_work(priv->workqueue, &priv->restart);
                return -ENOSPC;
        }
 
-       spin_lock_irqsave(&priv->hcmd_lock, flags);
-
-       /* If this is a huge cmd, mark the huge flag also on the meta.flags
-        * of the _original_ cmd. This is used for DMA mapping clean up.
-        */
-       if (cmd->flags & CMD_SIZE_HUGE) {
-               idx = iwl_legacy_get_cmd_index(q, q->write_ptr, 0);
-               txq->meta[idx].flags = CMD_SIZE_HUGE;
-       }
-
        idx = iwl_legacy_get_cmd_index(q, q->write_ptr, cmd->flags & CMD_SIZE_HUGE);
        out_cmd = txq->cmd[idx];
        out_meta = &txq->meta[idx];
 
+       if (WARN_ON(out_meta->flags & CMD_MAPPED)) {
+               spin_unlock_irqrestore(&priv->hcmd_lock, flags);
+               return -ENOSPC;
+       }
+
        memset(out_meta, 0, sizeof(*out_meta)); /* re-initialize to NULL */
-       out_meta->flags = cmd->flags;
+       out_meta->flags = cmd->flags | CMD_MAPPED;
        if (cmd->flags & CMD_WANT_SKB)
                out_meta->source = cmd;
        if (cmd->flags & CMD_ASYNC)
@@ -610,6 +607,7 @@ iwl_legacy_tx_cmd_complete(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb)
        struct iwl_device_cmd *cmd;
        struct iwl_cmd_meta *meta;
        struct iwl_tx_queue *txq = &priv->txq[priv->cmd_queue];
+       unsigned long flags;
 
        /* If a Tx command is being handled and it isn't in the actual
         * command queue then there a command routing bug has been introduced
@@ -623,14 +621,6 @@ iwl_legacy_tx_cmd_complete(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb)
                return;
        }
 
-       /* If this is a huge cmd, clear the huge flag on the meta.flags
-        * of the _original_ cmd. So that iwl_legacy_cmd_queue_free won't unmap
-        * the DMA buffer for the scan (huge) command.
-        */
-       if (huge) {
-               cmd_index = iwl_legacy_get_cmd_index(&txq->q, index, 0);
-               txq->meta[cmd_index].flags = 0;
-       }
        cmd_index = iwl_legacy_get_cmd_index(&txq->q, index, huge);
        cmd = txq->cmd[cmd_index];
        meta = &txq->meta[cmd_index];
@@ -647,6 +637,8 @@ iwl_legacy_tx_cmd_complete(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb)
        } else if (meta->callback)
                meta->callback(priv, cmd, pkt);
 
+       spin_lock_irqsave(&priv->hcmd_lock, flags);
+
        iwl_legacy_hcmd_queue_reclaim(priv, txq_id, index, cmd_index);
 
        if (!(meta->flags & CMD_ASYNC)) {
@@ -655,6 +647,10 @@ iwl_legacy_tx_cmd_complete(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb)
                               iwl_legacy_get_cmd_string(cmd->hdr.cmd));
                wake_up_interruptible(&priv->wait_command_queue);
        }
+
+       /* Mark as unmapped */
        meta->flags = 0;
+
+       spin_unlock_irqrestore(&priv->hcmd_lock, flags);
 }
 EXPORT_SYMBOL(iwl_legacy_tx_cmd_complete);