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iwlwifi: fix enqueue hcmd race conditions

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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.

On the way fix whitespace.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Stanislaw Gruszka 2011-03-31 17:36:26 +02:00 • committed by John W. Linville
commit 3598e1774c
2 changed files with 34 additions and 29 deletions
Download patch file Download diff file Expand all files Collapse all files

1
drivers/net/wireless/iwlwifi/iwl-dev.h
View file

@ -309,6 +309,7 @@ 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

62
drivers/net/wireless/iwlwifi/iwl-tx.c
View file

@ -149,32 +149,31 @@ void iwl_cmd_queue_unmap(struct iwl_priv *priv)
struct iwl_tx_queue *txq = &priv->txq[priv->cmd_queue];
struct iwl_queue *q = &txq->q;
int i;
bool huge = false;
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 = 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_queue_inc_wrap(q->read_ptr, q->n_bd);
q->read_ptr = iwl_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;
}
}
@ -463,7 +462,11 @@ int iwl_enqueue_hcmd(struct iwl_priv *priv, struct iwl_host_cmd *cmd)
return -EIO;
}
spin_lock_irqsave(&priv->hcmd_lock, flags);
if (iwl_queue_space(q) < ((cmd->flags & CMD_ASYNC) ? 2 : 1)) {
spin_unlock_irqrestore(&priv->hcmd_lock, flags);
IWL_ERR(priv, "No space in command queue\n");
if (priv->cfg->ops->lib->tt_ops.ct_kill_check) {
is_ct_kill =
@ -476,22 +479,17 @@ int iwl_enqueue_hcmd(struct iwl_priv *priv, struct iwl_host_cmd *cmd)
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 = get_cmd_index(q, q->write_ptr, 0);
txq->meta[idx].flags = CMD_SIZE_HUGE;
}
idx = 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)
@ -609,6 +607,10 @@ void iwl_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;
void (*callback) (struct iwl_priv *priv, struct iwl_device_cmd *cmd,
struct iwl_rx_packet *pkt);
/* 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
@ -622,14 +624,8 @@ void iwl_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_cmd_queue_free won't unmap
* the DMA buffer for the scan (huge) command.
*/
if (huge) {
cmd_index = get_cmd_index(&txq->q, index, 0);
txq->meta[cmd_index].flags = 0;
}
spin_lock_irqsave(&priv->hcmd_lock, flags);
cmd_index = get_cmd_index(&txq->q, index, huge);
cmd = txq->cmd[cmd_index];
meta = &txq->meta[cmd_index];
@ -639,12 +635,13 @@ void iwl_tx_cmd_complete(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb)
dma_unmap_len(meta, len),
PCI_DMA_BIDIRECTIONAL);
callback = NULL;
/* Input error checking is done when commands are added to queue. */
if (meta->flags & CMD_WANT_SKB) {
meta->source->reply_page = (unsigned long)rxb_addr(rxb);
rxb->page = NULL;
} else if (meta->callback)
meta->callback(priv, cmd, pkt);
} else
callback = meta->callback;
iwl_hcmd_queue_reclaim(priv, txq_id, index, cmd_index);
@ -654,5 +651,12 @@ void iwl_tx_cmd_complete(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb)
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);
if (callback)
callback(priv, cmd, pkt);
}