iwlwifi: pcie: allow sending pre-built A-MSDUs

In case of A-MSDUs, the trans layer is taking care of building
the subframes (out of the given skb), according to the given gso_size.

However, in some testing flows, we want to build the whole A-MSDU
frame in a different place (e.g. userspace), and ask the driver
to send it as-is.

In case of gso_size==0, simply treat the frame as normal-frame,
although the A-MSDU flag is set.

Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/pcie/tx.c

@@ -2397,7 +2397,13 @@ int iwl_trans_pcie_tx(struct iwl_trans *trans, struct sk_buff *skb,
 		goto out_err;
 	iwl_pcie_txq_build_tfd(trans, txq, tb1_phys, tb1_len, false);
 
-	if (amsdu) {
+	/*
+	 * If gso_size wasn't set, don't give the frame "amsdu treatment"
+	 * (adding subframes, etc.).
+	 * This can happen in some testing flows when the amsdu was already
+	 * pre-built, and we just need to send the resulting skb.
+	 */
+	if (amsdu && skb_shinfo(skb)->gso_size) {
 		if (unlikely(iwl_fill_data_tbs_amsdu(trans, skb, txq, hdr_len,
 						     out_meta, dev_cmd,
 						     tb1_len)))