iwlwifi: pcie: allocate smaller dev_cmd for TX headers

As noted in the previous commit, due to the way we allocate the
dev_cmd headers with 324 byte size, and 4/8 byte alignment, the
part we use of them (bytes 20..40-68) could still cross a page
and thus 2^32 boundary.

Address this by using alignment to ensure that the allocation
cannot cross a page boundary, on hardware that's affected. To
make that not cause more memory consumption, reduce the size of
the allocations to the necessary size - we go from 324 bytes in
each allocation to 60/68 on gen2 depending on family, and ~120
or so on gen1 (so on gen1 it's a pure reduction in size, since
we don't need alignment there).

To avoid size and clearing issues, add a new structure that's
just the header, and use kmem_cache_zalloc().

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

1 files changed, 15 insertions, 6 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c b/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
index a2dc380ac17c..56d752beb940 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c
@@ -365,7 +365,8 @@ trace:
 static int iwl_pcie_gen2_build_amsdu(struct iwl_trans *trans,
 				     struct sk_buff *skb,
 				     struct iwl_tfh_tfd *tfd, int start_len,
-				     u8 hdr_len, struct iwl_device_cmd *dev_cmd)
+				     u8 hdr_len,
+				     struct iwl_device_tx_cmd *dev_cmd)
 {
 #ifdef CONFIG_INET
 	struct iwl_tx_cmd_gen2 *tx_cmd = (void *)dev_cmd->payload;
@@ -496,7 +497,7 @@ out_err:
 static struct
 iwl_tfh_tfd *iwl_pcie_gen2_build_tx_amsdu(struct iwl_trans *trans,
 					  struct iwl_txq *txq,
-					  struct iwl_device_cmd *dev_cmd,
+					  struct iwl_device_tx_cmd *dev_cmd,
 					  struct sk_buff *skb,
 					  struct iwl_cmd_meta *out_meta,
 					  int hdr_len,
@@ -533,6 +534,10 @@ iwl_tfh_tfd *iwl_pcie_gen2_build_tx_amsdu(struct iwl_trans *trans,
 	tb_phys = dma_map_single(trans->dev, tb1_addr, len, DMA_TO_DEVICE);
 	if (unlikely(dma_mapping_error(trans->dev, tb_phys)))
 		goto out_err;
+	/*
+	 * No need for _with_wa(), we ensure (via alignment) that the data
+	 * here can never cross or end at a page boundary.
+	 */
 	iwl_pcie_gen2_set_tb(trans, tfd, tb_phys, len);
 
 	if (iwl_pcie_gen2_build_amsdu(trans, skb, tfd,
@@ -580,7 +585,7 @@ static int iwl_pcie_gen2_tx_add_frags(struct iwl_trans *trans,
 static struct
 iwl_tfh_tfd *iwl_pcie_gen2_build_tx(struct iwl_trans *trans,
 				    struct iwl_txq *txq,
-				    struct iwl_device_cmd *dev_cmd,
+				    struct iwl_device_tx_cmd *dev_cmd,
 				    struct sk_buff *skb,
 				    struct iwl_cmd_meta *out_meta,
 				    int hdr_len,
@@ -625,6 +630,10 @@ iwl_tfh_tfd *iwl_pcie_gen2_build_tx(struct iwl_trans *trans,
 	tb_phys = dma_map_single(trans->dev, tb1_addr, tb1_len, DMA_TO_DEVICE);
 	if (unlikely(dma_mapping_error(trans->dev, tb_phys)))
 		goto out_err;
+	/*
+	 * No need for _with_wa(), we ensure (via alignment) that the data
+	 * here can never cross or end at a page boundary.
+	 */
 	iwl_pcie_gen2_set_tb(trans, tfd, tb_phys, tb1_len);
 	trace_iwlwifi_dev_tx(trans->dev, skb, tfd, sizeof(*tfd), &dev_cmd->hdr,
 			     IWL_FIRST_TB_SIZE + tb1_len, hdr_len);
@@ -671,7 +680,7 @@ out_err:
 static
 struct iwl_tfh_tfd *iwl_pcie_gen2_build_tfd(struct iwl_trans *trans,
 					    struct iwl_txq *txq,
-					    struct iwl_device_cmd *dev_cmd,
+					    struct iwl_device_tx_cmd *dev_cmd,
 					    struct sk_buff *skb,
 					    struct iwl_cmd_meta *out_meta)
 {
@@ -711,7 +720,7 @@ struct iwl_tfh_tfd *iwl_pcie_gen2_build_tfd(struct iwl_trans *trans,
 }
 
 int iwl_trans_pcie_gen2_tx(struct iwl_trans *trans, struct sk_buff *skb,
-			   struct iwl_device_cmd *dev_cmd, int txq_id)
+			   struct iwl_device_tx_cmd *dev_cmd, int txq_id)
 {
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
 	struct iwl_cmd_meta *out_meta;
@@ -736,7 +745,7 @@ int iwl_trans_pcie_gen2_tx(struct iwl_trans *trans, struct sk_buff *skb,
 
 		/* don't put the packet on the ring, if there is no room */
 		if (unlikely(iwl_queue_space(trans, txq) < 3)) {
-			struct iwl_device_cmd **dev_cmd_ptr;
+			struct iwl_device_tx_cmd **dev_cmd_ptr;
 
 			dev_cmd_ptr = (void *)((u8 *)skb->cb +
 					       trans_pcie->dev_cmd_offs);