V4L/DVB (8751): vivi: Fix some issues at vivi register routine

This patch fixes several small issues at vivi register routines:

1) minor and n_devs should be unsigned;
2) n_devs = 0 were not properly handled;
3) if n_devs specify a high number, the driver would just roll back and
won't register any device. The proper behaviour is to keep all succeded
devices registered;
4) both n_devs and minor were using 0 as permissions. Better to have
them with 0444.

With the current patch, if n_devs specify a very large value, it will
register all possible devices. For example, on a machine without any
other V4L drivers loaded, with this patch, we will have something like:

vivi: V4L2 device registered as /dev/video0
vivi: V4L2 device registered as /dev/video1
vivi: V4L2 device registered as /dev/video2
	...
vivi: V4L2 device registered as /dev/video31
video_register_device_index: get_index failed
Video Technology Magazine Virtual Video Capture Board ver 0.5.0 successfully loaded.

5) The number of allocated devices on success is now kept at n_devs:

$ cat /sys/module/vivi/parameters/n_devs
32

Thanks to Henne <henne@nachtwindheim.de> for pointing that there were
some issues at vivi.

Cc: Henne <henne@nachtwindheim.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 36 insertions, 8 deletions

diff --git a/drivers/media/video/vivi.c b/drivers/media/video/vivi.c
index 3518af071a2e..f55d77db1558 100644
--- a/drivers/media/video/vivi.c
+++ b/drivers/media/video/vivi.c
@@ -1104,19 +1104,29 @@ static struct video_device vivi_template = {
         Initialization and module stuff
    ------------------------------------------------------------------*/
 
+/* This routine allocates from 1 to n_devs virtual drivers.
+
+   The real maximum number of virtual drivers will depend on how many drivers
+   will succeed. This is limited to the maximum number of devices that
+   videodev supports. Since there are 64 minors for video grabbers, this is
+   currently the theoretical maximum limit. However, a further limit does
+   exist at videodev that forbids any driver to register more than 32 video
+   grabbers.
+ */
 static int __init vivi_init(void)
 {
         int ret = -ENOMEM, i;
         struct vivi_dev *dev;
         struct video_device *vfd;
 
+        if (n_devs <= 0)
+                n_devs = 1;
+
         for (i = 0; i < n_devs; i++) {
                 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
-                if (NULL == dev)
+                if (!dev)
                         break;
 
-                list_add_tail(&dev->vivi_devlist, &vivi_devlist);
-
                 /* init video dma queues */
                 INIT_LIST_HEAD(&dev->vidq.active);
                 init_waitqueue_head(&dev->vidq.wq);
@@ -1126,14 +1136,27 @@ static int __init vivi_init(void)
                 mutex_init(&dev->mutex);
 
                 vfd = video_device_alloc();
-                if (NULL == vfd)
+                if (!vfd) {
+                        kfree(dev);
                         break;
+                }
 
                 *vfd = vivi_template;
 
                 ret = video_register_device(vfd, VFL_TYPE_GRABBER, video_nr);
-                if (ret < 0)
+                if (ret < 0) {
+                        video_device_release(vfd);
+                        kfree(dev);
+
+                        /* If some registers succeeded, keep driver */
+                        if (i)
+                                ret = 0;
+
                         break;
+                }
+
+                /* Now that everything is fine, let's add it to device list */
+                list_add_tail(&dev->vivi_devlist, &vivi_devlist);
 
                 snprintf(vfd->name, sizeof(vfd->name), "%s (%i)",
                          vivi_template.name, vfd->minor);
@@ -1149,11 +1172,16 @@ static int __init vivi_init(void)
         if (ret < 0) {
                 vivi_release();
                 printk(KERN_INFO "Error %d while loading vivi driver\n", ret);
-        } else
+        } else {
                 printk(KERN_INFO "Video Technology Magazine Virtual Video "
                         "Capture Board ver %u.%u.%u successfully loaded.\n",
                         (VIVI_VERSION >> 16) & 0xFF, (VIVI_VERSION >> 8) & 0xFF,
                         VIVI_VERSION & 0xFF);
+
+                /* n_devs will reflect the actual number of allocated devices */
+                n_devs = i;
+        }
+
         return ret;
 }
 
@@ -1169,10 +1197,10 @@ MODULE_DESCRIPTION("Video Technology Magazine Virtual Video Capture Board");
 MODULE_AUTHOR("Mauro Carvalho Chehab, Ted Walther and John Sokol");
 MODULE_LICENSE("Dual BSD/GPL");
 
-module_param(video_nr, int, 0);
+module_param(video_nr, uint, 0444);
 MODULE_PARM_DESC(video_nr, "video iminor start number");
 
-module_param(n_devs, int, 0);
+module_param(n_devs, uint, 0444);
 MODULE_PARM_DESC(n_devs, "number of video devices to create");
 
 module_param_named(debug, vivi_template.debug, int, 0444);