spi: davinci: check for NULL buffer pointer before using it

In the davinci_spi_{tx|rx}_u{8|16}() functions, check for
buffer pointer being valid before using it. While providing
for better error checking, this change will help simplify
code in the caller.

Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Tested-By: Michael Williamson <michael.williamson@criticallink.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>

diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
index b0b338fc44667d1dd4047c6d195be90e6587ba1e..10b0a08d262509066625cbc53f11894a2076b6e6 100644 (file)
--- a/drivers/spi/davinci_spi.c
+++ b/drivers/spi/davinci_spi.c
@@ -158,37 +158,41 @@ static unsigned use_dma;
 
 static void davinci_spi_rx_buf_u8(u32 data, struct davinci_spi *davinci_spi)
 {
-       u8 *rx = davinci_spi->rx;
-
-       *rx++ = (u8)data;
-       davinci_spi->rx = rx;
+       if (davinci_spi->rx) {
+               u8 *rx = davinci_spi->rx;
+               *rx++ = (u8)data;
+               davinci_spi->rx = rx;
+       }
 }
 
 static void davinci_spi_rx_buf_u16(u32 data, struct davinci_spi *davinci_spi)
 {
-       u16 *rx = davinci_spi->rx;
-
-       *rx++ = (u16)data;
-       davinci_spi->rx = rx;
+       if (davinci_spi->rx) {
+               u16 *rx = davinci_spi->rx;
+               *rx++ = (u16)data;
+               davinci_spi->rx = rx;
+       }
 }
 
 static u32 davinci_spi_tx_buf_u8(struct davinci_spi *davinci_spi)
 {
-       u32 data;
-       const u8 *tx = davinci_spi->tx;
-
-       data = *tx++;
-       davinci_spi->tx = tx;
+       u32 data = 0;
+       if (davinci_spi->tx) {
+               const u8 *tx = davinci_spi->tx;
+               data = *tx++;
+               davinci_spi->tx = tx;
+       }
        return data;
 }
 
 static u32 davinci_spi_tx_buf_u16(struct davinci_spi *davinci_spi)
 {
-       u32 data;
-       const u16 *tx = davinci_spi->tx;
-
-       data = *tx++;
-       davinci_spi->tx = tx;
+       u32 data = 0;
+       if (davinci_spi->tx) {
+               const u16 *tx = davinci_spi->tx;
+               data = *tx++;
+               davinci_spi->tx = tx;
+       }
        return data;
 }