Use dev_lock for alloc_find_dev()

If threads called alloc_find_dev() with same device_path
simultaneously, two device nodes could be allocated.
This bug is not triggered by current code.

Change-Id: Ifc87021c8d6f422901c5de5dd17392e3e2309afa
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/1188
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-by: Sven Schnelle <svens@stackframe.org>

1 files changed, 27 insertions, 3 deletions

diff --git a/src/devices/device.c b/src/devices/device.c
index ebac1a073e..fafa59924e 100644
--- a/src/devices/device.c
+++ b/src/devices/device.c
@@ -66,12 +66,10 @@ DECLARE_SPIN_LOCK(dev_lock)
  *
  * @see device_path
  */
-device_t alloc_dev(struct bus *parent, struct device_path *path)
+static device_t __alloc_dev(struct bus *parent, struct device_path *path)
 {
 	device_t dev, child;
 
-	spin_lock(&dev_lock);
-
 	/* Find the last child of our parent. */
 	for (child = parent->children; child && child->sibling; /* */ )
 		child = child->sibling;
@@ -99,11 +97,37 @@ device_t alloc_dev(struct bus *parent, struct device_path *path)
 	last_dev->next = dev;
 	last_dev = dev;
 
+	return dev;
+}
+
+device_t alloc_dev(struct bus *parent, struct device_path *path)
+{
+	device_t dev;
+	spin_lock(&dev_lock);
+	dev = __alloc_dev(parent, path);
 	spin_unlock(&dev_lock);
 	return dev;
 }
 
 /**
+ * See if a device structure already exists and if not allocate it.
+ *
+ * @param parent The bus to find the device on.
+ * @param path The relative path from the bus to the appropriate device.
+ * @return Pointer to a device structure for the device on bus at path.
+ */
+device_t alloc_find_dev(struct bus *parent, struct device_path *path)
+{
+	device_t child;
+	spin_lock(&dev_lock);
+	child = find_dev_path(parent, path);
+	if (!child)
+		child = __alloc_dev(parent, path);
+	spin_unlock(&dev_lock);
+	return child;
+}
+
+/**
  * Round a number up to an alignment.
  *
  * @param val The starting value.