Re: [PATCH] ATA: Fix port removal ordering

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Monday, November 25, 2013 01:19:01 PM Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> After commit bcdde7e221a8 (sysfs: make __sysfs_remove_dir() recursive)
> Mika Westerberg sees traces analogous to the one below in Thunderbolt
> hot-remove testing:
> 
>  WARNING: CPU: 0 PID: 4 at fs/sysfs/group.c:214 sysfs_remove_group+0xc6/0xd0()
>  sysfs group ffffffff81c6f1e0 not found for kobject 'host7'
>  Modules linked in:
>  CPU: 0 PID: 4 Comm: kworker/0:0 Not tainted 3.12.0+ #13
>  Hardware name:                  /D33217CK, BIOS GKPPT10H.86A.0042.2013.0422.1439 04/22/2013
>  Workqueue: kacpi_hotplug acpi_hotplug_work_fn
>   0000000000000009 ffff8801002459b0 ffffffff817daab1 ffff8801002459f8
>   ffff8801002459e8 ffffffff810436b8 0000000000000000 ffffffff81c6f1e0
>   ffff88006d440358 ffff88006d440188 ffff88006e8b4c28 ffff880100245a48
>  Call Trace:
>   [<ffffffff817daab1>] dump_stack+0x45/0x56
>   [<ffffffff810436b8>] warn_slowpath_common+0x78/0xa0
>   [<ffffffff81043727>] warn_slowpath_fmt+0x47/0x50
>   [<ffffffff811ad319>] ? sysfs_get_dirent_ns+0x49/0x70
>   [<ffffffff811ae526>] sysfs_remove_group+0xc6/0xd0
>   [<ffffffff81432f7e>] dpm_sysfs_remove+0x3e/0x50
>   [<ffffffff8142a0d0>] device_del+0x40/0x1b0
>   [<ffffffff8142a24d>] device_unregister+0xd/0x20
>   [<ffffffff8144131a>] scsi_remove_host+0xba/0x110
>   [<ffffffff8145f526>] ata_host_detach+0xc6/0x100
>   [<ffffffff8145f578>] ata_pci_remove_one+0x18/0x20
>   [<ffffffff812e8f48>] pci_device_remove+0x28/0x60
>   [<ffffffff8142d854>] __device_release_driver+0x64/0xd0
>   [<ffffffff8142d8de>] device_release_driver+0x1e/0x30
>   [<ffffffff8142d257>] bus_remove_device+0xf7/0x140
>   [<ffffffff8142a1b1>] device_del+0x121/0x1b0
>   [<ffffffff812e43d4>] pci_stop_bus_device+0x94/0xa0
>   [<ffffffff812e437b>] pci_stop_bus_device+0x3b/0xa0
>   [<ffffffff812e437b>] pci_stop_bus_device+0x3b/0xa0
>   [<ffffffff812e44dd>] pci_stop_and_remove_bus_device+0xd/0x20
>   [<ffffffff812fc743>] trim_stale_devices+0x73/0xe0
>   [<ffffffff812fc78b>] trim_stale_devices+0xbb/0xe0
>   [<ffffffff812fc78b>] trim_stale_devices+0xbb/0xe0
>   [<ffffffff812fcb6e>] acpiphp_check_bridge+0x7e/0xd0
>   [<ffffffff812fd90d>] hotplug_event+0xcd/0x160
>   [<ffffffff812fd9c5>] hotplug_event_work+0x25/0x60
>   [<ffffffff81316749>] acpi_hotplug_work_fn+0x17/0x22
>   [<ffffffff8105cf3a>] process_one_work+0x17a/0x430
>   [<ffffffff8105db29>] worker_thread+0x119/0x390
>   [<ffffffff8105da10>] ? manage_workers.isra.25+0x2a0/0x2a0
>   [<ffffffff81063a5d>] kthread+0xcd/0xf0
>   [<ffffffff81063990>] ? kthread_create_on_node+0x180/0x180
>   [<ffffffff817eb33c>] ret_from_fork+0x7c/0xb0
>   [<ffffffff81063990>] ? kthread_create_on_node+0x180/0x180
> 
> The source of this problem is that SCSI hosts are removed from
> ATA ports after calling ata_tport_delete() which removes the
> port's sysfs directory, among other things.  Now, after commit
> bcdde7e221a8, the sysfs directory is removed along with all of
> its subdirectories that include the SCSI host's sysfs directory
> and its subdirectories at this point.  Consequently, when
> device_del() is finally called for any child device of the SCSI
> host and tries to remove its "power" group (which is already
> gone then), it triggers the above warning.
> 
> To make the warnings go away, change the removal ordering in
> ata_port_detach() so that the SCSI host is removed from the
> port before ata_tport_delete() is called.
> 
> References: https://bugzilla.kernel.org/show_bug.cgi?id=65281
> Reported-and-tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> 
> Hi,
> 
> This along with https://patchwork.kernel.org/patch/3226081/ makes
> all of the warnings observed by Mika go away without the patch at
> https://patchwork.kernel.org/patch/3201841/ applied.

Any news here?

Gwendal has agreed with this patch. :-)

Thanks,
Rafael


> ---
>  drivers/ata/libata-core.c |    3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> Index: linux-pm/drivers/ata/libata-core.c
> ===================================================================
> --- linux-pm.orig/drivers/ata/libata-core.c
> +++ linux-pm/drivers/ata/libata-core.c
> @@ -6304,10 +6304,9 @@ static void ata_port_detach(struct ata_p
>  		for (i = 0; i < SATA_PMP_MAX_PORTS; i++)
>  			ata_tlink_delete(&ap->pmp_link[i]);
>  	}
> -	ata_tport_delete(ap);
> -
>  	/* remove the associated SCSI host */
>  	scsi_remove_host(ap->scsi_host);
> +	ata_tport_delete(ap);
>  }
>  
>  /**
> 
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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.