wimax/i2400m: limit the message size upto 16KiB [v1]

According to Intel Wimax i3200, i5x50 and i6x50 specification
documents, the maximum size of each TX message can be upto 16KiB.
This patch modifies the i2400m_tx() routine to check that the
message size does not exceed the 16KiB limit.
Please refer the documentation in the code for details.

Signed-off-by: Prasanna S. Panchamukhi <prasannax.s.panchamukhi@intel.com>

drivers/net/wimax/i2400m/tx.c

@@ -282,6 +282,11 @@ enum {
 	I2400M_TX_PLD_SIZE = sizeof(struct i2400m_msg_hdr)
 	+ I2400M_TX_PLD_MAX * sizeof(struct i2400m_pld),
 	I2400M_TX_SKIP = 0x80000000,
+	/*
+	 * According to Intel Wimax i3200, i5x50 and i6x50 specification
+	 * documents, the maximum size of each message can be up to 16KiB.
+	 */
+	I2400M_TX_MSG_SIZE = 16384,
 	/*
 	 * 16 byte aligned MAX_MTU + 4 byte payload prefix.
 	 */
@@ -682,7 +687,13 @@ int i2400m_tx(struct i2400m *i2400m, const void *buf, size_t buf_len,
 	}
 	if (i2400m->tx_msg == NULL)
 		goto error_tx_new;
-	if (i2400m->tx_msg->size + padded_len > I2400M_TX_BUF_SIZE / 2) {
+	/*
+	 * Check if this skb will fit in the TX queue's current active
+	 * TX message. The total message size must not exceed the maximum
+	 * size of each message I2400M_TX_MSG_SIZE. If it exceeds,
+	 * close the current message and push this skb into the new message.
+	 */
+	if (i2400m->tx_msg->size + padded_len > I2400M_TX_MSG_SIZE) {
 		d_printf(2, dev, "TX: message too big, going new\n");
 		i2400m_tx_close(i2400m);
 		i2400m_tx_new(i2400m);