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Date: Fri, 15 Apr 2016 13:53:48 +0800
From: Xiong Zhou <jencce.kernel@...il.com>
To: James Bottomley <jejb@...ux.vnet.ibm.com>
Cc: Johannes Thumshirn <jthumshirn@...e.de>,
Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
"Ewan D. Milne" <emilne@...hat.com>,
Hannes Reinecke <hare@...e.com>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Stephen Rothwell <sfr@...b.auug.org.au>,
linux-scsi@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-usb@...r.kernel.org, Linux-Next <linux-next@...r.kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [-next] BUG_ON in scsi_target_destroy()
Hi,
On Wed, Apr 13, 2016 at 11:14 PM, James Bottomley
<jejb@...ux.vnet.ibm.com> wrote:
> On Wed, 2016-04-13 at 10:41 +0200, Johannes Thumshirn wrote:
>> Hi Sergey, Xiong,
>>
>> Can you try below patch?
>>
>> On Montag, 11. April 2016 18:01:47 CEST Sergey Senozhatsky wrote:
>> > Hello,
>> >
>> > commit 7b106f2de6938c31ce5e9c86bc70ad3904666b96
>> > Author: Johannes Thumshirn <jthumshirn@...e.de>
>> > Date: Tue Apr 5 11:50:44 2016 +0200
>> >
>> > scsi: Add intermediate STARGET_REMOVE state to
>> > scsi_target_state
>> >
>> >
>> > BUG_ON()s (next-20160411) each time I remove a usb flash
>> >
>> > [ 49.561600] [<ffffffffa0087f42>] scsi_target_destroy+0x5a/0xcb
>> > [scsi_mod]
>> > [ 49.561607] [<ffffffffa0089099>] scsi_target_reap+0x4a/0x4f
>> > [scsi_mod]
>> > [ 49.561613] [<ffffffffa008b453>] __scsi_remove_device+0xc3/0xd0
>> > [scsi_mod]
>> > [ 49.561619] [<ffffffffa0089d7b>] scsi_forget_host+0x52/0x63
>> > [scsi_mod]
>> > [ 49.561623] [<ffffffffa0080dbc>] scsi_remove_host+0x8c/0x102
>> > [scsi_mod]
>> > [ 49.561627] [<ffffffffa015c447>] usb_stor_disconnect+0x6b/0xab
>> > [usb_storage]
>> > [ 49.561634] [<ffffffffa0013f73>]
>> > usb_unbind_interface+0x77/0x1ca [usbcore]
>> > [ 49.561636] [<ffffffff813ae064>]
>> > __device_release_driver+0x9d/0x121
>> > [ 49.561638] [<ffffffff813ae10b>]
>> > device_release_driver+0x23/0x30
>> > [ 49.561639] [<ffffffff813ad2d1>] bus_remove_device+0xfb/0x10e
>> > [ 49.561641] [<ffffffff813aac05>] device_del+0x164/0x1e6
>> > [ 49.561648] [<ffffffffa0011b09>] ?
>> > remove_intf_ep_devs+0x3b/0x48 [usbcore]
>> > [ 49.561655] [<ffffffffa001200e>] usb_disable_device+0x84/0x1a5
>> > [usbcore]
>> > [ 49.561661] [<ffffffffa000ac7b>] usb_disconnect+0x94/0x19f
>> > [usbcore]
>> > [ 49.561667] [<ffffffffa000c2ab>] hub_event+0x5c1/0xdea
>> > [usbcore]
>> > [ 49.561670] [<ffffffff810530b1>] process_one_work+0x1dc/0x37f
>> > [ 49.561672] [<ffffffff81053dc5>] worker_thread+0x282/0x36d
>> > [ 49.561673] [<ffffffff81053b43>] ? rescuer_thread+0x2ae/0x2ae
>> > [ 49.561675] [<ffffffff810580a8>] kthread+0xd2/0xda
>> > [ 49.561678] [<ffffffff814bbf92>] ret_from_fork+0x22/0x40
>> > [ 49.561679] [<ffffffff81057fd6>] ?
>> > kthread_worker_fn+0x13e/0x13e
>> >
>> > -ss
>> > --
>> > To unsubscribe from this list: send the line "unsubscribe linux
>> > -scsi" in
>> > the body of a message to majordomo@...r.kernel.org
>> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>> >
>>
>> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
>> index 0734927..0c00928 100644
>> --- a/drivers/scsi/scsi_sysfs.c
>> +++ b/drivers/scsi/scsi_sysfs.c
>> @@ -1276,6 +1276,7 @@ int scsi_sysfs_add_sdev(struct scsi_device
>> *sdev)
>> void __scsi_remove_device(struct scsi_device *sdev)
>> {
>> struct device *dev = &sdev->sdev_gendev;
>> + struct scsi_target *starget;
>>
>> /*
>> * This cleanup path is not reentrant and while it is
>> impossible
>> @@ -1315,7 +1316,9 @@ void __scsi_remove_device(struct scsi_device
>> *sdev)
>> * remoed sysfs visibility from the device, so make the
>> target
>> * invisible if this was the last device underneath it.
>> */
>> - scsi_target_reap(scsi_target(sdev));
>> + starget = scsi_target(sdev);
>> + starget->state = STARGET_REMOVE;
>> + scsi_target_reap(starget);
>
> How about good grief no! A device with multiple targets will get it's
> lists screwed with this
>
> The STARGET_REMOVE state you added only applies to the case we're
> trying to kill a target. In the natural operation case, which is what
> everyone else is running into, we will try to remove a running target
> when it has no more scsi devices left on it. So the correct patch
> should be to make the BUG_ON see this:
>
> James
>
> ---
>
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 27df7e7..e0a78f5 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -319,8 +319,7 @@ static void scsi_target_destroy(struct scsi_target *starget)
> struct Scsi_Host *shost = dev_to_shost(dev->parent);
> unsigned long flags;
>
> - BUG_ON(starget->state != STARGET_REMOVE &&
> - starget->state != STARGET_CREATED);
> + BUG_ON(starget->state == STARGET_DEL);
> starget->state = STARGET_DEL;
> transport_destroy_device(dev);
> spin_lock_irqsave(shost->host_lock, flags);
>
This will survive modprobe -r scsi_debug ..
Just to make sure, is this _REMOVE state able to do the latter thing what it was
trying to do, in this way ?
commit 7b106f2de6938c31ce5e9c86bc70ad3904666b96
Author: Johannes Thumshirn <jthumshirn@...e.de>
Date: Tue Apr 5 11:50:44 2016 +0200
scsi: Add intermediate STARGET_REMOVE state to scsi_target_state
Add intermediate STARGET_REMOVE state to scsi_target_state to avoid
running into the BUG_ON() in scsi_target_reap(). The STARGET_REMOVE
state is only valid in the path from scsi_remove_target() to
scsi_target_destroy() indicating this target is going to be removed.
This re-fixes the problem introduced in commits bc3f02a795d3 ("[SCSI]
scsi_remove_target: fix softlockup regression on hot remove") and
40998193560d ("scsi: restart list search after unlock in
scsi_remove_target") in a more comprehensive way.
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