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SubjectRe: 2.6.0-test2, compact flash, IDE, and kobject errors

On Wed, 6 Aug 2003, J.C. Wren wrote:

> As I've mentioned before, I have an embedded Linux system that has been
> running 2.2.12, and I'm looking at bringing it up to a modern kernel for some
> features that we're looking at implementing. It's a 386EX system, 2MB flash
> (for BIOS and kernel), 8MB RAM, and a 32MB compact flash card.
>
> WIth both 2.5.69 (last version I attempted), and 2.6.0-test2, when the CF is
> probed, I would get a message indicating kobject had failed with an EEXISTS
> error code. After the the kernel spits out the message about the HD size,
> I'd get:
>
> hda: hda1
> hda: hda1
> (then the kobject failure and stack trace)
>
> After a lot of printk's, I determine that the kernel is attempting to register
> the partition or drive twice. This happens because in fs/partions/check.c,
> register_disk() calls blkdev_get(). If blkdev_get() sees the media change
> flag set, he calls rescan_partitions(), which causes the partition to be
> registered. After it returns, register_disk() calls add_partition(), which
> results in the kernel throwing a kobject error that it's already registered.
>
> The solution that I think is correct (the audience LAUGH sign is now lit) is
> to add a 'hdx=removable' and 'hdx=notremovable' config parameter. If you are
> booting from a removable media device, such as a CF card (and certain items
> like floppies seems to be special cased out, which I'm guessing is why you
> don't see this on certain media types), this flag would override the
> removable flag determined by the probe. And for whatever reason someone
> might want to, a non-removable device could be marked as removable.

Known problem. "ide-cs stack_dump" thread :-).
Does this patch help?

drivers/ide/ide-disk.c | 7 +++++++
drivers/ide/ide-floppy.c | 8 +++++++-
include/linux/ide.h | 1 +
3 files changed, 15 insertions(+), 1 deletion(-)

diff -puN drivers/ide/ide-disk.c~ide-attach-flag drivers/ide/ide-disk.c
--- linux-2.6.0-test2-bk3/drivers/ide/ide-disk.c~ide-attach-flag 2003-08-05 01:43:03.312872768 +0200
+++ linux-2.6.0-test2-bk3-root/drivers/ide/ide-disk.c 2003-08-05 01:48:44.197050496 +0200
@@ -1790,6 +1790,12 @@ static int idedisk_ioctl(struct inode *i
static int idedisk_media_changed(struct gendisk *disk)
{
ide_drive_t *drive = disk->private_data;
+
+ /* do not scan partitions twice if we are attaching this device */
+ if (drive->attach) {
+ drive->attach = 0;
+ return 0;
+ }
/* if removable, always assume it was changed */
return drive->removable;
}
@@ -1848,6 +1854,7 @@ static int idedisk_attach(ide_drive_t *d
g->flags = drive->removable ? GENHD_FL_REMOVABLE : 0;
set_capacity(g, current_capacity(drive));
g->fops = &idedisk_ops;
+ drive->attach = 1;
add_disk(g);
return 0;
failed:
diff -puN drivers/ide/ide-floppy.c~ide-attach-flag drivers/ide/ide-floppy.c
--- linux-2.6.0-test2-bk3/drivers/ide/ide-floppy.c~ide-attach-flag 2003-08-05 01:43:06.710356272 +0200
+++ linux-2.6.0-test2-bk3-root/drivers/ide/ide-floppy.c 2003-08-05 01:48:59.546716992 +0200
@@ -2006,7 +2006,12 @@ static int idefloppy_media_changed(struc
{
ide_drive_t *drive = disk->private_data;
idefloppy_floppy_t *floppy = drive->driver_data;
-
+
+ /* do not scan partitions twice if we are attaching this device */
+ if (drive->attach) {
+ drive->attach = 0;
+ return 0;
+ }
return test_and_clear_bit(IDEFLOPPY_MEDIA_CHANGED, &floppy->flags);
}

@@ -2061,6 +2066,7 @@ static int idefloppy_attach (ide_drive_t
strcpy(g->devfs_name, drive->devfs_name);
g->flags = drive->removable ? GENHD_FL_REMOVABLE : 0;
g->fops = &idefloppy_ops;
+ drive->attach = 1;
add_disk(g);
return 0;
failed:
diff -puN include/linux/ide.h~ide-attach-flag include/linux/ide.h
--- linux-2.6.0-test2-bk3/include/linux/ide.h~ide-attach-flag 2003-08-05 01:43:14.735136320 +0200
+++ linux-2.6.0-test2-bk3-root/include/linux/ide.h 2003-08-05 01:45:19.069234664 +0200
@@ -711,6 +711,7 @@ typedef struct ide_drive_s {
unsigned id_read : 1; /* 1=id read from disk 0 = synthetic */
unsigned noprobe : 1; /* from: hdx=noprobe */
unsigned removable : 1; /* 1 if need to do check_media_change */
+ unsigned attach : 1; /* set to 1 in ->attach() */
unsigned is_flash : 1; /* 1 if probed as flash */
unsigned forced_geom : 1; /* 1 if hdx=c,h,s was given at boot */
unsigned no_unmask : 1; /* disallow setting unmask bit */
_

> I need to clean out a bunch of printks, but if this isn't the totally wrong
> approach, I'll submit a patch for it. So far, this patch seems to have fixed
> my problem.

Can you send your patch (even with bunch of printks)?

> One question I do have is that e2fsck seems phenominally slower under
> 2.6.0-test2 than 2.2.12. It's the same version of e2fsck, so I'm guessing
> the disk throughput is slower (it's all PIO), but I'm not sure what in the
> IDE driver could have halfed or one-thirded the disk throughput. Any
> thoughts on that would be greatly appreciated.

There was a bug in e2fsck resulting in CPU hogging.

What makes you think that the disk throughput is halfed?
Can you check with hdparm?

Thanks,
--
Bartlomiej


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