drm: simplify drm_*_set_unique()

Lets use kasprintf() to avoid pre-allocating the buffer. This is really
nothing to optimize for speed and the input is trusted, so kasprintf() is
just fine.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 16 insertions, 45 deletions

diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 020cfd934854..8efea6b4602b 100644
--- a/drivers/gpu/drm/drm_pci.c
+++ b/drivers/gpu/drm/drm_pci.c
@@ -129,31 +129,17 @@ static int drm_get_pci_domain(struct drm_device *dev)
 
 static int drm_pci_set_busid(struct drm_device *dev, struct drm_master *master)
 {
-        int len, ret;
-        master->unique_len = 40;
-        master->unique_size = master->unique_len;
-        master->unique = kmalloc(master->unique_size, GFP_KERNEL);
-        if (master->unique == NULL)
+        master->unique = kasprintf(GFP_KERNEL, "pci:%04x:%02x:%02x.%d",
+                                        drm_get_pci_domain(dev),
+                                        dev->pdev->bus->number,
+                                        PCI_SLOT(dev->pdev->devfn),
+                                        PCI_FUNC(dev->pdev->devfn));
+        if (!master->unique)
                 return -ENOMEM;
 
-
-        len = snprintf(master->unique, master->unique_len,
-                       "pci:%04x:%02x:%02x.%d",
-                       drm_get_pci_domain(dev),
-                       dev->pdev->bus->number,
-                       PCI_SLOT(dev->pdev->devfn),
-                       PCI_FUNC(dev->pdev->devfn));
-
-        if (len >= master->unique_len) {
-                DRM_ERROR("buffer overflow");
-                ret = -EINVAL;
-                goto err;
-        } else
-                master->unique_len = len;
-
+        master->unique_len = strlen(master->unique);
+        master->unique_size = master->unique_len + 1;
         return 0;
-err:
-        return ret;
 }
 
 int drm_pci_set_unique(struct drm_device *dev,
diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
index d5b76f148c12..0c09ddd50c15 100644
--- a/drivers/gpu/drm/drm_platform.c
+++ b/drivers/gpu/drm/drm_platform.c
@@ -70,35 +70,20 @@ err_free:
 
 static int drm_platform_set_busid(struct drm_device *dev, struct drm_master *master)
 {
-        int len, ret, id;
-
-        master->unique_len = 13 + strlen(dev->platformdev->name);
-        master->unique_size = master->unique_len;
-        master->unique = kmalloc(master->unique_len + 1, GFP_KERNEL);
-
-        if (master->unique == NULL)
-                return -ENOMEM;
+        int id;
 
         id = dev->platformdev->id;
-
-        /* if only a single instance of the platform device, id will be
-         * set to -1.. use 0 instead to avoid a funny looking bus-id:
-         */
-        if (id == -1)
+        if (id < 0)
                 id = 0;
 
-        len = snprintf(master->unique, master->unique_len,
-                        "platform:%s:%02d", dev->platformdev->name, id);
-
-        if (len > master->unique_len) {
-                DRM_ERROR("Unique buffer overflowed\n");
-                ret = -EINVAL;
-                goto err;
-        }
+        master->unique = kasprintf(GFP_KERNEL, "platform:%s:%02d",
+                                                dev->platformdev->name, id);
+        if (!master->unique)
+                return -ENOMEM;
 
+        master->unique_len = strlen(master->unique);
+        master->unique_size = master->unique_len;
         return 0;
-err:
-        return ret;
 }
 
 static struct drm_bus drm_platform_bus = {