[PATCH 3.19 033/175] rtlwifi: rtl8192ee: Fix problems with calculating free space in FIFO

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Larry Finger <Larry.Finger@lwfinger.net>

commit 6d4beca3775222884e1ee9d48ef586c438c3dfa1 upstream.

This driver utilizes a FIFO buffer for RX descriptors. There are four places
in the code where it calculates the number of free slots. Several of those
locations do the calculation incorrectly. To fix these and to prevent future
mistakes, a common inline routine is created.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/wireless/rtlwifi/pci.h           |    7 +++++++
 drivers/net/wireless/rtlwifi/rtl8192ee/trx.c |    9 +--------
 2 files changed, 8 insertions(+), 8 deletions(-)

--- a/drivers/net/wireless/rtlwifi/pci.h
+++ b/drivers/net/wireless/rtlwifi/pci.h
@@ -325,4 +325,11 @@ static inline void pci_write32_async(str
 	writel(val, (u8 __iomem *) rtlpriv->io.pci_mem_start + addr);
 }
 
+static inline u16 calc_fifo_space(u16 rp, u16 wp)
+{
+	if (rp <= wp)
+		return RTL_PCI_MAX_RX_COUNT - 1 + rp - wp;
+	return rp - wp - 1;
+}
+
 #endif
--- a/drivers/net/wireless/rtlwifi/rtl8192ee/trx.c
+++ b/drivers/net/wireless/rtlwifi/rtl8192ee/trx.c
@@ -658,14 +658,7 @@ u16 rtl92ee_rx_desc_buff_remained_cnt(st
 	if (!start_rx)
 		return 0;
 
-	if ((last_read_point > (RX_DESC_NUM_92E / 2)) &&
-	    (read_point <= (RX_DESC_NUM_92E / 2))) {
-		remind_cnt = RX_DESC_NUM_92E - write_point;
-	} else {
-		remind_cnt = (read_point >= write_point) ?
-			     (read_point - write_point) :
-			     (RX_DESC_NUM_92E - write_point + read_point);
-	}
+	remind_cnt = calc_fifo_space(read_point, write_point);
 
 	if (remind_cnt == 0)
 		return 0;