1 files changed, 23 insertions, 22 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index b31f4431849b..682a6a48fec3 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -485,6 +485,15 @@ void spi_unregister_master(struct spi_master *master)
 }
 EXPORT_SYMBOL_GPL(spi_unregister_master);
 
+static int __spi_master_match(struct device *dev, void *data)
+{
+        struct spi_master *m;
+        u16 *bus_num = data;
+
+        m = container_of(dev, struct spi_master, dev);
+        return m->bus_num == *bus_num;
+}
+
 /**
  * spi_busnum_to_master - look up master associated with bus_num
  * @bus_num: the master's bus number
@@ -499,17 +508,12 @@ struct spi_master *spi_busnum_to_master(u16 bus_num)
 {
         struct device           *dev;
         struct spi_master       *master = NULL;
-        struct spi_master       *m;
-
-        down(&spi_master_class.sem);
-        list_for_each_entry(dev, &spi_master_class.children, node) {
-                m = container_of(dev, struct spi_master, dev);
-                if (m->bus_num == bus_num) {
-                        master = spi_master_get(m);
-                        break;
-                }
-        }
-        up(&spi_master_class.sem);
+
+        dev = class_find_device(&spi_master_class, &bus_num,
+                                __spi_master_match);
+        if (dev)
+                master = container_of(dev, struct spi_master, dev);
+        /* reference got in class_find_device */
         return master;
 }
 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
@@ -541,10 +545,7 @@ static void spi_complete(void *arg)
  * Also, the caller is guaranteeing that the memory associated with the
  * message will not be freed before this call returns.
  *
- * The return value is a negative error code if the message could not be
- * submitted, else zero.  When the value is zero, then message->status is
- * also defined;  it's the completion code for the transfer, either zero
- * or a negative error code from the controller driver.
+ * It returns zero on success, else a negative error code.
  */
 int spi_sync(struct spi_device *spi, struct spi_message *message)
 {
@@ -554,8 +555,10 @@ int spi_sync(struct spi_device *spi, struct spi_message *message)
         message->complete = spi_complete;
         message->context = &done;
         status = spi_async(spi, message);
-        if (status == 0)
+        if (status == 0) {
                 wait_for_completion(&done);
+                status = message->status;
+        }
         message->context = NULL;
         return status;
 }
@@ -589,7 +592,7 @@ int spi_write_then_read(struct spi_device *spi,
                 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;
@@ -615,7 +618,7 @@ int spi_write_then_read(struct spi_device *spi,
         }
 
         /* ... 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;
@@ -628,13 +631,11 @@ int spi_write_then_read(struct spi_device *spi,
 
         /* do the i/o */
         status = spi_sync(spi, &message);
-        if (status == 0) {
+        if (status == 0)
                 memcpy(rxbuf, x[1].rx_buf, n_rx);
-                status = message.status;
-        }
 
         if (x[0].tx_buf == buf)
-                up(&lock);
+                mutex_unlock(&lock);
         else
                 kfree(local_buf);