On Fri, 2007-10-19 at 13:11 -0400, Alan Stern wrote:
> On Fri, 19 Oct 2007, Kay Sievers wrote:


> > > Don't you have a USB storage device? It should be easy for you to

> test
> > > this on your own system.

> >
> > Sure, I have, and tried a lot of times, and all seemed correct here

> with
> > the final put. I don't say that it's the right fix, but without it,

> the
> > disk device object is never released here, it only gets removed from
> > sysfs.

>
> Well, attached is a testing patch. It should apply to 2.6.23
> together
> with gregkh-all-2.6.23. Here's the output on my system using your
> original code:
>

....

> As you can see, this definitely proves that the final put is done at
> the right time.
>
> See what the patch shows on your system. One extra thing to check for:
> When you plug in a USB drive, the SCSI core starts up an error-handler
> process for it. When you unplug the drive, the error-handler task
> should exit. If it doesn't then there's an extra reference somewhere
> that never got released.


Here is what I see, the error handler hangs without the final put and
the kobject never gets cleaned up. Note the missing:
kobject sdb: cleaning up

What is your CONFIG_SYSFS_DEPRECATED option? I have it unset, and that
may be the difference in the behavior if you have it set.

Thanks,
Kay


With device_put() - add sequence:
sd_probe: call add_disk
start of register_disk: 1
kobject block: registering. parent: 9:0:0:0, set:
unset subsytem caused the event to drop!
kobject sdb: registering. parent: block, set: devices
kobject filter function caused the event to drop!
after device_add: 3
after sysfs_create_link: 3
kobject holders: registering. parent: sdb, set:
kobject filter function caused the event to drop!
kobject slaves: registering. parent: sdb, set:
kobject filter function caused the event to drop!
after disk_sysfs_add_subdirs: 5
after get_capacity: 5
after bdget_disk: 5
sd 9:0:0:0: [sdb] 127840 512-byte hardware sectors (65 MB)
sd 9:0:0:0: [sdb] Write Protect is off
sd 9:0:0:0: [sdb] Mode Sense: 45 00 00 08
sd 9:0:0:0: [sdb] Assuming drive cache: write through
sdb: sdb1
kobject sdb1: registering. parent: sdb, set: devices
kobject filter function caused the event to drop!
kobject holders: registering. parent: sdb1, set:
kobject filter function caused the event to drop!
after blkdev_get: 8
after blkdev_put: 7
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host9/target9:0:0/9:0:0:0/block/sdb'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host9/target9:0:0/9:0:0:0/block/sdb/sdb1'
end of register_disk: 7
kobject queue: registering. parent: sdb, set:
kobject filter function caused the event to drop!
kobject iosched: registering. parent: queue, set:
kobject filter function caused the event to drop!
after blk_register_queue: 9
sd 9:0:0:0: [sdb] Attached SCSI removable disk
kobject 9:0:0:0: registering. parent: scsi_device, set: class_obj
fill_kobj_path: path = '/class/scsi_device/9:0:0:0'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host9/target9:0:0/9:0:0:0'
kobject sg2: registering. parent: scsi_generic, set: class_obj
fill_kobj_path: path = '/class/scsi_generic/sg2'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host9/target9:0:0/9:0:0:0'
sd 9:0:0:0: Attached scsi generic sg2 type 0
kobject 9:0:0:0: registering. parent: bsg, set: class_obj
fill_kobj_path: path = '/class/bsg/9:0:0:0'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host9/target9:0:0/9:0:0:0'
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject target9:0:1: registering. parent: host9, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target9:0:1: cleaning up
kobject target9:0:2: registering. parent: host9, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target9:0:2: cleaning up
kobject target9:0:3: registering. parent: host9, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target9:0:3: cleaning up
kobject target9:0:4: registering. parent: host9, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target9:0:4: cleaning up
kobject target9:0:5: registering. parent: host9, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target9:0:5: cleaning up
kobject target9:0:6: registering. parent: host9, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target9:0:6: cleaning up
kobject target9:0:7: registering. parent: host9, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target9:0:7: cleaning up
usb-storage: device scan complete

With device_put() - eh_9 created:
23 ? S< 0:00 \_ [scsi_eh_0]
24 ? S< 0:00 \_ [scsi_eh_1]
25 ? S< 0:00 \_ [scsi_eh_2]
26 ? S< 0:00 \_ [scsi_eh_3]
27 ? S< 0:00 \_ [scsi_eh_4]
28 ? S< 0:00 \_ [scsi_eh_5]
2149 ? S< 0:00 \_ [scsi_eh_9]
2182 tty1 S+ 0:00 \_ grep eh


With device_put() - remove sequence:
sd_remove: call del_gendisk
start of del_gendisk: 9
kobject holders: unregistering
kobject filter function caused the event to drop!
kobject holders: cleaning up
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host9/target9:0:0/9:0:0:0/block/sdb/sdb1'
kobject sdb1: cleaning up
after deleting subpartitions: 7
after invalidate_partition(0): 7
kobject filter function caused the event to drop!
kobject filter function caused the event to drop!
after unlink_gendisk: 6
kobject holders: unregistering
kobject filter function caused the event to drop!
kobject holders: cleaning up
kobject slaves: unregistering
kobject filter function caused the event to drop!
kobject slaves: cleaning up
after kobject_unregister subdirs: 4
after sysfs_remove_link: 4
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host9/target9:0:0/9:0:0:0/block/sdb'
after device_del: 2
after put_device: 1
kobject 9:0:0:0: cleaning up
scsi_disk_release: call put_disk
kobject sdb: cleaning up
kobject block: cleaning up
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host9/target9:0:0/9:0:0:0'
kobject 9:0:0:0: cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target9:0:0: cleaning up
fill_kobj_path: path = '/class/scsi_host/host9'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host9'
kobject host9: cleaning up
kobject filter function caused the event to drop!
kobject host9: cleaning up
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0'
kobject 1-2:1.0: cleaning up
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/usb_endpoint/usbdev1.6_ep00'
kobject usbdev1.6_ep00: cleaning up
kobject usb_endpoint: cleaning up
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2'
kobject 1-2: cleaning up

With device_put() - eh_9 removed:
23 ? S< 0:00 \_ [scsi_eh_0]
24 ? S< 0:00 \_ [scsi_eh_1]
25 ? S< 0:00 \_ [scsi_eh_2]
26 ? S< 0:00 \_ [scsi_eh_3]
27 ? S< 0:00 \_ [scsi_eh_4]
28 ? S< 0:00 \_ [scsi_eh_5]
2199 tty1 S+ 0:00 \_ grep eh



Without device_put() - add sequence:
sd_probe: call add_disk
start of register_disk: 1
kobject block: registering. parent: 8:0:0:0, set:
unset subsytem caused the event to drop!
kobject sdb: registering. parent: block, set: devices
kobject filter function caused the event to drop!
after device_add: 3
after sysfs_create_link: 3
kobject holders: registering. parent: sdb, set:
kobject filter function caused the event to drop!
kobject slaves: registering. parent: sdb, set:
kobject filter function caused the event to drop!
after disk_sysfs_add_subdirs: 5
after get_capacity: 5
after bdget_disk: 5
sd 8:0:0:0: [sdb] 127840 512-byte hardware sectors (65 MB)
sd 8:0:0:0: [sdb] Write Protect is off
sd 8:0:0:0: [sdb] Mode Sense: 45 00 00 08
sd 8:0:0:0: [sdb] Assuming drive cache: write through
sdb: sdb1
kobject sdb1: registering. parent: sdb, set: devices
kobject filter function caused the event to drop!
kobject holders: registering. parent: sdb1, set:
kobject filter function caused the event to drop!
after blkdev_get: 8
after blkdev_put: 7
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host8/target8:0:0/8:0:0:0/block/sdb'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host8/target8:0:0/8:0:0:0/block/sdb/sdb1'
end of register_disk: 7
kobject queue: registering. parent: sdb, set:
kobject filter function caused the event to drop!
kobject iosched: registering. parent: queue, set:
kobject filter function caused the event to drop!
after blk_register_queue: 9
sd 8:0:0:0: [sdb] Attached SCSI removable disk
kobject 8:0:0:0: registering. parent: scsi_device, set: class_obj
fill_kobj_path: path = '/class/scsi_device/8:0:0:0'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host8/target8:0:0/8:0:0:0'
kobject sg2: registering. parent: scsi_generic, set: class_obj
fill_kobj_path: path = '/class/scsi_generic/sg2'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host8/target8:0:0/8:0:0:0'
sd 8:0:0:0: Attached scsi generic sg2 type 0
kobject 8:0:0:0: registering. parent: bsg, set: class_obj
fill_kobj_path: path = '/class/bsg/8:0:0:0'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host8/target8:0:0/8:0:0:0'
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject target8:0:1: registering. parent: host8, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target8:0:1: cleaning up
kobject target8:0:2: registering. parent: host8, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target8:0:2: cleaning up
kobject target8:0:3: registering. parent: host8, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target8:0:3: cleaning up
kobject target8:0:4: registering. parent: host8, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target8:0:4: cleaning up
kobject target8:0:5: registering. parent: host8, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target8:0:5: cleaning up
kobject target8:0:6: registering. parent: host8, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target8:0:6: cleaning up
kobject target8:0:7: registering. parent: host8, set: devices
kobject filter function caused the event to drop!
kobject : cleaning up
kobject iosched: cleaning up
kobject queue: cleaning up
kobject filter function caused the event to drop!
kobject target8:0:7: cleaning up
usb-storage: device scan complete

Without device_put() - eh_8 created:
23 ? S< 0:00 \_ [scsi_eh_0]
24 ? S< 0:00 \_ [scsi_eh_1]
25 ? S< 0:00 \_ [scsi_eh_2]
26 ? S< 0:00 \_ [scsi_eh_3]
27 ? S< 0:00 \_ [scsi_eh_4]
28 ? S< 0:00 \_ [scsi_eh_5]
1965 ? S< 0:00 \_ [scsi_eh_6]
2014 ? S< 0:00 \_ [scsi_eh_7]
2066 ? S< 0:00 \_ [scsi_eh_8]
2098 tty1 S+ 0:00 \_ grep eh


Without device_put() - remove sequence:
sd_remove: call del_gendisk
start of del_gendisk: 9
kobject holders: unregistering
kobject filter function caused the event to drop!
kobject holders: cleaning up
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host8/target8:0:0/8:0:0:0/block/sdb/sdb1'
kobject sdb1: cleaning up
after deleting subpartitions: 7
after invalidate_partition(0): 7
kobject filter function caused the event to drop!
kobject filter function caused the event to drop!
after unlink_gendisk: 6
kobject holders: unregistering
kobject filter function caused the event to drop!
kobject holders: cleaning up
kobject slaves: unregistering
kobject filter function caused the event to drop!
kobject slaves: cleaning up
after kobject_unregister subdirs: 4
after sysfs_remove_link: 4
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host8/target8:0:0/8:0:0:0/block/sdb'
after device_del: 2
after put_device: 2
kobject 8:0:0:0: cleaning up
scsi_disk_release: call put_disk
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host8/target8:0:0/8:0:0:0'
fill_kobj_path: path = '/class/scsi_host/host8'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0/host8'
kobject host8: cleaning up
kobject filter function caused the event to drop!
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/1-2:1.0'
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2/usb_endpoint/usbdev1.4_ep00'
kobject usbdev1.4_ep00: cleaning up
kobject usb_endpoint: cleaning up
fill_kobj_path: path = '/devices/pci0000:00/0000:00:1d.0/usb1/1-2'

Without device_put() - eh_8 hanging around:
23 ? S< 0:00 \_ [scsi_eh_0]
24 ? S< 0:00 \_ [scsi_eh_1]
25 ? S< 0:00 \_ [scsi_eh_2]
26 ? S< 0:00 \_ [scsi_eh_3]
27 ? S< 0:00 \_ [scsi_eh_4]
28 ? S< 0:00 \_ [scsi_eh_5]
1965 ? S< 0:00 \_ [scsi_eh_6]
2014 ? S< 0:00 \_ [scsi_eh_7]
2066 ? S< 0:00 \_ [scsi_eh_8]
2118 tty1 S+ 0:00 \_ grep eh



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