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>

1 files changed, 22 insertions, 18 deletions

diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
index b0b338fc4466..10b0a08d2625 100644
--- 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;
 }