V4L/DVB (6334): cx88: Change (struct cx8802_dev)->drvlist to a list_head and fix bugs

It was a struct cx8802_driver for no apparent reason.  Nothing uses a
cx8802_driver in the cx8802_dev struct.  The only field that was used was
devlist, a list_head.

The code in cx8802_remove() that removed any loaded sub-drivers was broken.
It would delete the current list entry, but didn't use list_for_each_safe.  It
also called list_del() on the list _head_ inside the list_for_each loop?  It
would crash if it was run, which I don't think can ever happen.

Since the cx8802 sub-drivers use the cx8802 driver, they have to be unloaded
first.  So there isn't any way for a sub-driver to still be loaded when
cx8802_remove() is called...  Except maybe with PCI hot-plug, if one removes
the PCI card while the drivers are loaded?

So I left some code in to handle that if it's actually possible.  It will
remove the sub-drivers from the device cx8802_remove() was called on, and only
that device.  If one has two DVB cards and unplugs one, there is no reason to
unload the DVB drivers for both cards.  I have no way to test this, but it
can't be worse than what was there before.

cx8802_get_driver() is passed a cx8802_dev pointer and looks for the requested
driver on that device.  It first loops over the cx8802 device list looking for
the device it was passed, which is pointless.  It doesn't need to find the
device pointer in the list, as it already has the pointer.

The list_head in the cx8802_driver struct, which joins all the _drivers_
attached to a device, was named devlist.  Changed that to drvlist, since the
devlist is used for a list of _devices_ in other cx8802 structs.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Reviewed-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 29 insertions, 31 deletions

diff --git a/drivers/media/video/cx88/cx88-mpeg.c b/drivers/media/video/cx88/cx88-mpeg.c
index 1b1418241b4..11d9865e34f 100644
--- a/drivers/media/video/cx88/cx88-mpeg.c
+++ b/drivers/media/video/cx88/cx88-mpeg.c
@@ -594,24 +594,14 @@ EXPORT_SYMBOL(cx8802_get_device);
 
 struct cx8802_driver * cx8802_get_driver(struct cx8802_dev *dev, enum cx88_board_type btype)
 {
-        struct cx8802_dev *h = NULL;
-        struct cx8802_driver *d = NULL;
+        struct cx8802_driver *d;
         struct list_head *list;
-        struct list_head *list2;
-
-        list_for_each(list,&cx8802_devlist) {
-                h = list_entry(list, struct cx8802_dev, devlist);
-                if (h != dev)
-                        continue;
 
-                list_for_each(list2, &h->drvlist.devlist) {
-                        d = list_entry(list2, struct cx8802_driver, devlist);
+        list_for_each(list, &dev->drvlist) {
+                d = list_entry(list, struct cx8802_driver, drvlist);
 
-                        /* only unregister the correct driver type */
-                        if (d->type_id == btype) {
-                                return d;
-                        }
-                }
+                if (d->type_id == btype)
+                        return d;
         }
 
         return NULL;
@@ -717,7 +707,7 @@ int cx8802_register_driver(struct cx8802_driver *drv)
                 if (err == 0) {
                         i++;
                         mutex_lock(&drv->core->lock);
-                        list_add_tail(&driver->devlist,&h->drvlist.devlist);
+                        list_add_tail(&driver->drvlist, &h->drvlist);
                         mutex_unlock(&drv->core->lock);
                 } else {
                         printk(KERN_ERR
@@ -757,8 +747,8 @@ int cx8802_unregister_driver(struct cx8802_driver *drv)
                        h->pci->subsystem_device, h->core->board.name,
                        h->core->boardnr);
 
-                list_for_each_safe(list2, q, &h->drvlist.devlist) {
-                        d = list_entry(list2, struct cx8802_driver, devlist);
+                list_for_each_safe(list2, q, &h->drvlist) {
+                        d = list_entry(list2, struct cx8802_driver, drvlist);
 
                         /* only unregister the correct driver type */
                         if (d->type_id != drv->type_id)
@@ -772,7 +762,6 @@ int cx8802_unregister_driver(struct cx8802_driver *drv)
                         } else
                                 printk(KERN_ERR "%s/2: cx8802 driver remove "
                                        "failed (%d)\n", h->core->name, err);
-
                 }
 
         }
@@ -810,7 +799,7 @@ static int __devinit cx8802_probe(struct pci_dev *pci_dev,
         if (err != 0)
                 goto fail_free;
 
-        INIT_LIST_HEAD(&dev->drvlist.devlist);
+        INIT_LIST_HEAD(&dev->drvlist);
         list_add_tail(&dev->devlist,&cx8802_devlist);
 
         /* Maintain a reference so cx88-video can query the 8802 device. */
@@ -830,23 +819,32 @@ static int __devinit cx8802_probe(struct pci_dev *pci_dev,
 static void __devexit cx8802_remove(struct pci_dev *pci_dev)
 {
         struct cx8802_dev *dev;
-        struct cx8802_driver *h;
-        struct list_head *list;
 
         dev = pci_get_drvdata(pci_dev);
 
         dprintk( 1, "%s\n", __FUNCTION__);
 
-        list_for_each(list,&dev->drvlist.devlist) {
-                h = list_entry(list, struct cx8802_driver, devlist);
-                dprintk( 1, " ->driver\n");
-                if (h->remove == NULL) {
-                        printk(KERN_ERR "%s .. skipping driver, no probe function\n", __FUNCTION__);
-                        continue;
+        if (!list_empty(&dev->drvlist)) {
+                struct list_head *list, *tmp;
+                struct cx8802_driver *drv;
+                int err;
+
+                printk(KERN_WARNING "%s/2: Trying to remove cx8802 driver "
+                       "while cx8802 sub-drivers still loaded?!\n",
+                       dev->core->name);
+
+                list_for_each_safe(list, tmp, &dev->drvlist) {
+                        drv = list_entry(list, struct cx8802_driver, drvlist);
+
+                        err = drv->remove(drv);
+                        if (err == 0) {
+                                mutex_lock(&drv->core->lock);
+                                list_del(list);
+                                mutex_unlock(&drv->core->lock);
+                        } else
+                                printk(KERN_ERR "%s/2: cx8802 driver remove "
+                                       "failed (%d)\n", dev->core->name, err);
                 }
-                printk(KERN_INFO "%s .. Removing driver type %d\n", __FUNCTION__, h->type_id);
-                cx8802_unregister_driver(h);
-                list_del(&dev->drvlist.devlist);
         }
 
         /* Destroy any 8802 reference. */