Date:	Wed, 11 Sep 2013 16:26:22 +0800
From:	Joe Jin <joe.jin@...cle.com>
To:	James Bottomley <James.Bottomley@...senPartnership.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-scsi@...r.kernel.org
Subject: Re: [PATCH] [scsi] enclosure: remove all possible sysfs entries before
 add device

On 09/10/13 20:46, James Bottomley wrote:
>> > During our test, multipath used, each LUN has 2 paths. when adding second
>> > path enclousure did not check if will adding device's symlink existed or no.
> The description doesn't look helpful.  The problem, presumably in a
> remove/re-add test that the add event gets processed before the remove
> event, which is why the link is still there?

Attach my debug info to here:

sd 7:0:27:0: [ses_intf_add]:cdev:ffff8817e81fcba0,intf:ffffffffa00c9400,sdev:ffff8817e81fc800
sd 7:0:27:0: [ses_intf_add] call ses_match_to_enclosure(edev=ffff8817e812c000,sdev=ffff8817e81fc800), cdev=ffff8817e81fcba0
sd 7:0:27:0: *** inq[6]: 48
sd 7:0:27:0: [sdq] 1172123568 512-byte logical blocks: (600 GB/558 GiB)
sd 7:0:27:0: [sdq] Write Protect is off
ADD: [enclosure_add_links]: kobj: <ffff8817e812cce8> target: <ffff8817e81fc948>, device
ADD: [enclosure_add_links]: kobj: <ffff8817e81fc948> target: <ffff8817e812cce8>, name: enclosure_device:HDD10
[ses_enclosure_find_by_addr] call enclosure_add_device(edev=ffff8817e812c000,i=4,efd->dev=ffff8817e81fc938),cdev=ffff8817e812ccd0
sd 7:0:27:0: [ses_intf_add] call ses_match_to_enclosure(edev=ffff8817ebd18000,sdev=ffff8817e81fc800), cdev=ffff8817e81fcba0
sd 7:0:27:0: *** inq[6]: 48
sd 7:0:27:0: [sdq] Write cache: disabled, read cache: enabled, supports DPO and FUA
[ses_enclosure_find_by_addr] call enclosure_add_device(edev=ffff8817e812c000,i=4,efd->dev=ffff8817e81fc938),cdev=ffff8817e812ccd0
sd 7:0:27:0: Attached scsi generic sg17 type 0
 sdq: sdq1 sdq2
scsi 6:0:27:0: SSP: handle(0x001c), sas_addr(0x5000c500006bd15e), phy(2), device_name(0x5000c500006bd15e)
scsi 6:0:27:0: SSP: enclosure_logical_id(0x5080020000a3a510), slot(10)
scsi 6:0:27:0: serial_number(000934E00P0S        3SL00P0S)
scsi 6:0:27:0: qdepth(254), tagged(1), simple(0), ordered(0), scsi_level(6), cmd_que(1)
sd 6:0:27:0: [ses_intf_add]:cdev:ffff8817e8304ba0,intf:ffffffffa00c9400,sdev:ffff8817e8304800
sd 6:0:27:0: [ses_intf_add] call ses_match_to_enclosure(edev=ffff8817e0c5c000,sdev=ffff8817e8304800), cdev=ffff8817e8304ba0
sd 6:0:27:0: *** inq[6]: 48
sd 6:0:27:0: [sdac] 1172123568 512-byte logical blocks: (600 GB/558 GiB)
sd 7:0:27:0: [sdq] Attached SCSI disk
RM: [enclosure_remove_links]: kobj: <ffff8817e81fc948> name: [enclosure_device:HDD10]
RM: [enclosure_remove_links]: kobj: <ffff8817e812cce8> device
sd 6:0:27:0: [sdac] Write Protect is off
ADD: [enclosure_add_links]: kobj: <ffff8817e812cce8> target: <ffff8817e8304948>, device
ADD: [enclosure_add_links]: kobj: <ffff8817e8304948> target: <ffff8817e812cce8>, name: enclosure_device:HDD10
[ses_enclosure_find_by_addr] call enclosure_add_device(edev=ffff8817e812c000,i=4,efd->dev=ffff8817e8304938),cdev=ffff8817e812ccd0
sd 6:0:27:0: [ses_intf_add] call ses_match_to_enclosure(edev=ffff8817e4094000,sdev=ffff8817e8304800), cdev=ffff8817e8304ba0
sd 6:0:27:0: *** inq[6]: 48
RM: [enclosure_remove_links]: kobj: <ffff8817e9a80948> name: [enclosure_device:HDD10]
RM: [enclosure_remove_links]: kobj: <ffff8817e4094ce8> device
ADD: [enclosure_add_links]: kobj: <ffff8817e4094ce8> target: <ffff8817e8304948>, device
ADD: [enclosure_add_links]: kobj: <ffff8817e8304948> target: <ffff8817e4094ce8>, name: enclosure_device:HDD10
------------[ cut here ]------------
WARNING: at fs/sysfs/dir.c:455 sysfs_add_one+0xbc/0xe0()
Hardware name: SUN FIRE X4370 M2 SERVER       
sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:03.0/0000:0d:00.0/host6/port-6:1/expander-6:1/port-6:1:14/end_device-6:1:14/target6:0:27/6:0:27:0/enclosure_device:HDD10' 
Modules linked in: oracleacfs(P)(U) oracleadvm(P)(U) oracleoks(P)(U) mptctl mptbase autofs4 hidp bluetooth rfkill lockd sunrpc bonding be2iscsi iscsi_boot_sysfs ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core ib_addr iscsi_tcp bnx2i cnic uio ipv6 cxgb3i libcxgbi cxgb3 mdio libiscsi_tcp libiscsi scsi_transport_iscsi dm_round_robin dm_multipath video sbs sbshc acpi_pad acpi_memhotplug acpi_ipmi parport_pc lp parport ipmi_si ipmi_devintf ipmi_msghandler sg ses enclosure ixgbe e1000e hwmon igb snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss snd_pcm snd_timer snd soundcore snd_page_alloc iTCO_wdt pcspkr i2c_i801 ioatdma ghes iTCO_vendor_support hed dca i2c_core i7core_edac edac_core dm_snapshot dm_zero dm_mirror dm_region_hash dm_log dm_mod usb_storage shpchp mpt2sas scsi_transport_sas raid_class ahci libahci sd_mod crc_t10dif raid1 ext3 jbd mbcache
Pid: 23302, comm: kworker/u:2 Tainted: P            2.6.39-400.124.1.el5uek.bug17342873V2 #1
Call Trace:
 [<ffffffff811daf8c>] ? sysfs_add_one+0xbc/0xe0
 [<ffffffff8106f030>] warn_slowpath_common+0x90/0xc0
 [<ffffffff8106f15e>] warn_slowpath_fmt+0x6e/0x70
 [<ffffffff81258bd4>] ? strlcat+0x54/0x70
 [<ffffffff811daf8c>] sysfs_add_one+0xbc/0xe0
 [<ffffffff811dbec8>] sysfs_do_create_link+0x148/0x1d0
 [<ffffffff811dbf83>] sysfs_create_link+0x13/0x20
 [<ffffffffa00de307>] enclosure_add_links+0xe7/0x110 [enclosure]
 [<ffffffff8125325d>] ? kobject_release+0xd/0x10
 [<ffffffff812549e7>] ? kref_put+0x37/0x70
 [<ffffffffa00de3c3>] enclosure_add_device+0x93/0xa0 [enclosure]
 [<ffffffffa00c8666>] ses_enclosure_find_by_addr+0x76/0xc0 [ses]
 [<ffffffffa00c85f0>] ? ses_get_fault+0x40/0x40 [ses]
 [<ffffffffa00de433>] enclosure_for_each_device+0x63/0x90 [enclosure]
 [<ffffffffa00c8a8a>] ses_match_to_enclosure+0x11a/0x1d0 [ses]
 [<ffffffffa00c8e08>] ses_intf_add+0x2c8/0x5c0 [ses]
 [<ffffffff8125327a>] ? kobject_get+0x1a/0x30
 [<ffffffff814e8b56>] ? add_tail+0x36/0x50
 [<ffffffff81345ae4>] device_add+0x2d4/0x380
 [<ffffffff8136b096>] scsi_sysfs_add_sdev+0xe6/0x2a0
 [<ffffffff813682cc>] scsi_add_lun+0x41c/0x560
 [<ffffffff81368a80>] scsi_probe_and_add_lun+0x1e0/0x3e0
 [<ffffffff81041009>] ? default_spin_lock_flags+0x9/0x10
 [<ffffffff813696e7>] __scsi_scan_target+0xe7/0x120
 [<ffffffff81369b8d>] scsi_scan_target+0xcd/0xf0
 [<ffffffffa003faab>] sas_rphy_add+0x11b/0x170 [scsi_transport_sas]
 [<ffffffffa009a74f>] mpt2sas_transport_port_add+0x2cf/0x430 [mpt2sas]
 [<ffffffffa008d437>] _scsih_sas_device_add+0x87/0x110 [mpt2sas]
 [<ffffffffa0094eb8>] _scsih_add_device+0x248/0x340 [mpt2sas]
 [<ffffffffa0098cb1>] ? mpt2sas_transport_update_links+0xf1/0x190 [mpt2sas]
 [<ffffffffa00977b6>] _scsih_sas_topology_change_event+0x3c6/0x490 [mpt2sas]
 [<ffffffff81080698>] ? add_timer+0x18/0x20
 [<ffffffff8108a405>] ? queue_delayed_work_on+0xc5/0x170
 [<ffffffffa0097a85>] _mpt2sas_fw_work+0x205/0x240 [mpt2sas]
 [<ffffffffa0097ad9>] _firmware_event_work_delayed+0x19/0x20 [mpt2sas]
 [<ffffffff8108c0d9>] process_one_work+0xf9/0x370
 [<ffffffffa0097ad9>] _firmware_event_work_delayed+0x19/0x20 [mpt2sas]
 [<ffffffff8108c0d9>] process_one_work+0xf9/0x370
 [<ffffffffa0097ac0>] ? _mpt2sas_fw_work+0x240/0x240 [mpt2sas]
 [<ffffffff8108ca1a>] worker_thread+0xca/0x240
 [<ffffffff8108c950>] ? manage_workers+0x90/0x90
 [<ffffffff81090ff7>] kthread+0x97/0xa0
 [<ffffffff8150fdc4>] kernel_thread_helper+0x4/0x10
 [<ffffffff81090f60>] ? kthread_bind+0x80/0x80
 [<ffffffff8150fdc0>] ? gs_change+0x13/0x13
---[ end trace 89a1351702ab360f ]---
[ses_enclosure_find_by_addr] call enclosure_add_device(edev=ffff8817e4094000,i=4,efd->dev=ffff8817e8304938),cdev=ffff8817e4094cd0

Per above message you can see the last tried for enclosure_device:HDD10, 
the index of component is not same then conflicted.

BTW, 6:0:27:0 and 7:0:27:0 are same disk.

> 
>> > Cc: James Bottomley <James.Bottomley@...senPartnership.com>
>> > Signed-off-by: Joe Jin <joe.jin@...cle.com>
>> > ---
>> >  drivers/misc/enclosure.c | 7 +++++++
>> >  1 file changed, 7 insertions(+)
>> > 
>> > diff --git a/drivers/misc/enclosure.c b/drivers/misc/enclosure.c
>> > index 0e8df41..efc0e86 100644
>> > --- a/drivers/misc/enclosure.c
>> > +++ b/drivers/misc/enclosure.c
>> > @@ -325,6 +325,13 @@ int enclosure_add_device(struct enclosure_device *edev, int component,
>> >  	if (cdev->dev)
>> >  		enclosure_remove_links(cdev);
>> >  
>> > +	if (dev) {
> This test is pointless.  Adding a NULL device is illegal.

Yes this is right.

Thanks,
Joe


> 
>> > +		char name[ENCLOSURE_NAME_SIZE];
>> > +
>> > +		enclosure_link_name(cdev, name);
>> > +		sysfs_remove_link(&dev->kobj, name);
> If we're really going to force eject the device, then this should be
> enclosure_remove_device(edev, dev);
> 
> How do you prevent the case for remove re-add in the same slot?  Surely
> in that case, with your code, the link will get removed again when the
> remove gets processed, so the slot will then look empty (even though
> it's not).


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