ide: indeed, using list_for_each_entry_safe removes endless looping / hang [Was: Re: 2.5.65-ac2 -- hda/ide trouble on ICH4]

[Dominik Brodowski <linux@brodo.de>]

On Sun, Mar 23, 2003 at 07:15:33PM +0100, Dominik Brodowski wrote:
> On Sun, Mar 23, 2003 at 06:41:10PM +0000, Alan Cox wrote:
> > > printk("%4s\n", drive->name) prints out "hdd" all the time. 
> > > 
> > > hda is an ATA disk drive
> > > hdb is empty
> > > hdc is an ATAPI CD/DVD-ROM drive
> > > hdd is an ATAPI CD-ROM CD-R/RW drive
> > 
> > This gets weirder by the minute, and I still can't get it to happen here
> > annoyingly.  
> >
> > The list thats breaking is a private list. We delete the drive from that
> > list, if its present (it may be an empty bay) we then use ata_attach 
> > to add it to a device list (or back to ata_unused). 
> > 
> > I find it hard to believe something like this is a compiler bug, but right
> > now I don't see how stuff is reappearing on the list.
> 
> Just got it to boot :) -- the while(!list_empty...) { list_entry ... looks
> suspicious. Might be better to use list_for_each_safe() which is designed
> exactly for this purpouse. I'm currently recompiling
> 2.5.65-bk-current-as-of-yesterday with the attached patch. Let's see whether
> it works with this kernel, too...

Yes, it also works with 2.5.65-bkX.

--- linux/drivers/ide/ide.c.original	2003-03-23 19:08:40.000000000 +0100
+++ linux/drivers/ide/ide.c	2003-03-23 19:10:25.000000000 +0100
@@ -2392,6 +2392,8 @@
 int ide_register_driver(ide_driver_t *driver)
 {
 	struct list_head list;
+	struct list_head *list_loop;
+	struct list_head *tmp_storage;
 
 	spin_lock(&drivers_lock);
 	list_add(&driver->drivers, &drivers);
@@ -2402,8 +2404,8 @@
 	list_splice_init(&ata_unused, &list);
 	spin_unlock(&drives_lock);
 
-	while (!list_empty(&list)) {
-		ide_drive_t *drive = list_entry(list.next, ide_drive_t, list);
+	list_for_each_safe(list_loop, tmp_storage, &list) {
+		ide_drive_t *drive = container_of(list_loop, ide_drive_t, list);
 		list_del_init(&drive->list);
 		if (drive->present)
 			ata_attach(drive);