From: David Brownell <david-b@pacbell.net>

Make spi_write_then_read() use a mutex not a binary semaphore.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/spi/spi.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff -puN drivers/spi/spi.c~spi-use-mutex-not-semaphore drivers/spi/spi.c
--- a/drivers/spi/spi.c~spi-use-mutex-not-semaphore
+++ a/drivers/spi/spi.c
@@ -588,7 +588,7 @@ int spi_write_then_read(struct spi_devic
 		const u8 *txbuf, unsigned n_tx,
 		u8 *rxbuf, unsigned n_rx)
 {
-	static DECLARE_MUTEX(lock);
+	static DEFINE_MUTEX(lock);
 
 	int			status;
 	struct spi_message	message;
@@ -614,7 +614,7 @@ int spi_write_then_read(struct spi_devic
 	}
 
 	/* ... unless someone else is using the pre-allocated buffer */
-	if (down_trylock(&lock)) {
+	if (!mutex_trylock(&lock)) {
 		local_buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
 		if (!local_buf)
 			return -ENOMEM;
@@ -633,7 +633,7 @@ int spi_write_then_read(struct spi_devic
 	}
 
 	if (x[0].tx_buf == buf)
-		up(&lock);
+		mutex_unlock(&lock);
 	else
 		kfree(local_buf);
 
_