On Monday 05/16 at 15:51 -0600, Sathya Prakash Veerichetty wrote: > Our understanding is the relationship between the SCSI host and SAS end > devices is a parent-child and before ripping of SCSI host we need to rip of > all the children. I know at least HPSA does the opposite, Elliott observes that other drivers do as well. > Why the enclosure ends up trying to re-parent the SCSI device from the > enclosure to the SAS PHY even after we remove the SAS Phy? Take this path in /sys: /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/host6/port-6:0/expander-6:0/port-6:0:0/end_device-6:0:0/target6:0:0/6:0:0:0/scsi_device/6:0:0:0 The problem is "port-6:0:0" in the hierarchy: since mpt3sas explicitly calls sas_port_delete() before scsi_remove_host(), that node is removed from the device hierarchy and seems to orphan what lies beneath it: [ 955.119328] kobject: '6:0:0:0' (ffff88074e2e1008): kobject_uevent_env [ 955.133890] kobject: '6:0:0:0' (ffff88074e2e1008): fill_kobj_path: path = '/end_device-6:0:0/target6:0:0/6:0:0:0/bsg/6:0:0:0' <WARN/OOPS sadness follows> As the above from CONFIG_DEBUG_KOBJECT suggests, "end_device-6:0:0" no longer has a parent. The path to the enclosured device is: /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/host6/port-6:0/expander-6:0/port-6:0:15/end_device-6:0:15/target6:0:15/6:0:15:0/enclosure/6:0:15:0/ArrayDevice09 Enclosure wants to re-add the device outside the enclosure: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/misc/enclosure.c#n404 We melt when trying to re-add "ArrayDevice09" to the "6:0:15:0" directory above the "enclosure" directory best I can tell. This is *incredibly* confusing because kobj_add_internal() actually clobbers the parent pointer if it's NULL: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/lib/kobject.c#n216 So even though it appears that the parent was "6:0:15:0" here, it was actually NULL when passed into kobj_add_internal(). Thus, we try to do the add with the kset as our parent, and we get -ENOENT because that node has been marked as inactive in kernfs as per here: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/fs/kernfs/dir.c#n743 Why is it inactive? I think, because __kernfs_remove() deleted an ancestor: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/fs/kernfs/dir.c#n1243 ...which brings us full circle. > Doesn't this need to be taken care in enclosure_removal? Even with enclosure compiled out, I still get a WARN like the following for every block device being removed at rmmod (-dirty here is just from me applying a fix to SES I sent to the list a few days ago): [ 224.057286] ------------[ cut here ]------------ [ 224.067696] WARNING: CPU: 1 PID: 5412 at fs/sysfs/group.c:237 sysfs_remove_group+0x10f/0x150 [ 224.088007] sysfs group ffffffff83109ba0 not found for kobject 'sdc' [ 224.102283] Modules linked in: mpt3sas(-) <snip> [ 224.200483] CPU: 0 PID: 5412 Comm: rmmod Not tainted 4.6.0-dirty #4 [ 224.219797] Hardware name: Wiwynn HoneyBadger/PantherPlus, BIOS HBM6.71 02/03/2016 [ 224.237001] ffffffff82af6280 ffff8806e826f8b0 ffffffff81e13e54 ffff8806e826f928 [ 224.253811] 0000000000000000 ffff8806e826f8f8 ffffffff81127822 ffffffff831a5968 [ 224.270647] ffff8806000000ed ffffed00dd04df21 0000000000000000 ffff880754ae3078 [ 224.287462] Call Trace: [ 224.292953] [<ffffffff81e13e54>] dump_stack+0x68/0x94 [ 224.304433] [<ffffffff81127822>] __warn+0x172/0x1b0 [ 224.315514] [<ffffffff811278f7>] warn_slowpath_fmt+0x97/0xb0 [ 224.351845] [<ffffffff816bbc1f>] sysfs_remove_group+0x10f/0x150 [ 224.365252] [<ffffffff81377814>] blk_trace_remove_sysfs+0x14/0x20 [ 224.379021] [<ffffffff81d966bf>] blk_unregister_queue+0xcf/0x120 [ 224.392589] [<ffffffff81dc8c7e>] del_gendisk+0x26e/0x600 [ 224.432345] [<ffffffff8215ea75>] sd_remove+0xf5/0x1b0 [ 224.443808] [<ffffffff820dd210>] __device_release_driver+0x160/0x3a0 [ 224.458151] [<ffffffff820dd475>] device_release_driver+0x25/0x40 [ 224.471734] [<ffffffff820dbd81>] bus_remove_device+0x2e1/0x4b0 [ 224.484926] [<ffffffff820d25ad>] device_del+0x37d/0x680 [ 224.555423] [<ffffffff82148225>] __scsi_remove_device+0x1e5/0x250 [ 224.569196] [<ffffffff821443bc>] scsi_forget_host+0x12c/0x1e0 [ 224.582197] [<ffffffff82120b6c>] scsi_remove_host+0x10c/0x300 [ 224.595227] [<ffffffffa0066cc9>] scsih_remove+0x339/0x670 [mpt3sas] [ 224.609383] [<ffffffff81edd400>] pci_device_remove+0x70/0x110 [ 224.622379] [<ffffffff820dd210>] __device_release_driver+0x160/0x3a0 [ 224.636724] [<ffffffff820de7b3>] driver_detach+0x183/0x200 [ 224.649166] [<ffffffff820dc61f>] bus_remove_driver+0xdf/0x200 [ 224.662185] [<ffffffff820df2e7>] driver_unregister+0x67/0xa0 [ 224.675009] [<ffffffff81edb2ee>] pci_unregister_driver+0x1e/0xe0 [ 224.688613] [<ffffffffa0093a3a>] _mpt3sas_exit+0x23/0x5e9 [mpt3sas] [ 224.702782] [<ffffffff812a2d1b>] SyS_delete_module+0x2eb/0x390 [ 224.743359] [<ffffffff829529e5>] entry_SYSCALL_64_fastpath+0x18/0xa8 [ 224.759036] ---[ end trace 13f1919bf2ec7bb0 ]--- My patch fixes that too :) The only driver besides mpt*sas that calls sas_delete_port() explicitly is HPSA, and it does it in the opposite order mpt3sas does: scsi_remove_host() first. Thanks, Calvin > -----Original Message----- > From: Calvin Owens [mailto:calvinowens@xxxxxx] > Sent: Monday, May 16, 2016 2:25 PM > To: Elliott, Robert (Persistent Memory) > Cc: Sathya Prakash; Chaitra P B; Suganath Prabu Subramani; James E.J. > Bottomley; Martin K. Petersen; MPT-FusionLinux.pdl@xxxxxxxxxxxx; > linux-scsi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > kernel-team@xxxxxx; calvinowens@xxxxxx > Subject: Re: [PATCH] mpt3sas: Do scsi_remove_host() before deleting SAS PHY > objects > > On Friday 05/13 at 21:17 +0000, Elliott, Robert (Persistent Memory) wrote: > > > > > > > -----Original Message----- > > > From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel- > > > owner@xxxxxxxxxxxxxxx] On Behalf Of Calvin Owens > > > Sent: Friday, May 13, 2016 3:28 PM > > ... > > > Subject: [PATCH] mpt3sas: Do scsi_remove_host() before deleting SAS > > > PHY objects > > > > > ... > > > The issue is that enclosure_remove_device() expects to be able to > > > re-add the device that was previously enclosured: so with SES > > > running, the order we unwind things matters in a way it otherwise > > > wouldn't. > > > > > > Since mpt3sas deletes the SAS objects before the SCSI hosts, > > > enclosure ends up trying to re-parent the SCSI device from the > > > enclosure to the SAS PHY which has already been deleted. This obviously > > > ends in sadness. > > > > > > The fix appears to be simple: just call scsi_remove_host() before we > > > call > > > sas_port_delete() and/or sas_remove_host(). > > > > > ... > > > diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c > > > @@ -8149,6 +8149,8 @@ void scsih_remove(struct pci_dev *pdev) > > > _scsih_raid_device_remove(ioc, raid_device); > > > } > > > > > > + scsi_remove_host(shost); > > > + > > > /* free ports attached to the sas_host */ > > > list_for_each_entry_safe(mpt3sas_port, next_port, > > > &ioc->sas_hba.sas_port_list, port_list) { @@ -8172,7 +8174,6 @@ > > > void scsih_remove(struct pci_dev *pdev) > > > } > > > > > > sas_remove_host(shost); > > > - scsi_remove_host(shost); > > > mpt3sas_base_detach(ioc); > > > spin_lock(&gioc_lock); > > > list_del(&ioc->list); > > > > That change matches the pattern of all other drivers calling > > sas_remove_host, except for one: > > drivers/message/fusion/mptsas.c > > > > That consensus means this comment in drivers/scsi/scsi_transport_sas.c > > is wrong: > > > > /** > > * sas_remove_host - tear down a Scsi_Host's SAS data structures > > * @shost: Scsi Host that is torn down > > * > > * Removes all SAS PHYs and remote PHYs for a given Scsi_Host. > > * Must be called just before scsi_remove_host for SAS HBAs. > > */ > > Yes, exactly: that comment appears to be backwards, and as you say most > drivers appear to do the opposite (I looked at HPSA at least, which calls > sas_port_delete() before scsi_remove_host()). > > I suppose I should send a patch to fix the comment as well? It'd be nice to > get some testing to be certain I'm not breaking somebody else's setup by > fixing mine though... > > Thanks, > Calvin -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
