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iwlegacy: 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.

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>
This commit is contained in:
Stanislaw Gruszka 2011-04-28 11:51:31 +02:00 committed by John W. Linville
parent 93fd74e3d5
commit 81e63263aa
2 changed files with 26 additions and 29 deletions
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1
drivers/net/wireless/iwlegacy/iwl-dev.h
View File

@ -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

54
drivers/net/wireless/iwlegacy/iwl-tx.c
View File

@ -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;
}
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");
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;
if (iwl_legacy_queue_space(q) < ((cmd->flags & CMD_ASYNC) ? 2 : 1)) {
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;
}
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);