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Date: Thu, 24 Mar 2011 20:23:33 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Pekka Enberg <penberg@kernel.org>, Christoph Lameter <cl@linux.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Ville Tervo <ville.tervo@nokia.com>,
        "Gustavo F. Padovan" <padovan@profusion.mobi>
Subject: Re: Call Trace:Re: [boot crash #2] Re: [GIT PULL] SLAB changes for
 v2.6.39-rc1
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* Thomas Gleixner <tglx@linutronix.de> wrote:

> After we made debugobjects working again, we got the following:
> 
> WARNING: at lib/debugobjects.c:262 debug_print_object+0x8e/0xb0()
> Hardware name: System Product Name
> ODEBUG: free active (active state 0) object type: timer_list hint: hci_cmd_timer+0x0/0x60
> Pid: 2125, comm: dmsetup Tainted: G        W   2.6.38-06707-gc62b389 #110375
> Call Trace:
>  [<ffffffff8104700a>] warn_slowpath_common+0x7a/0xb0
>  [<ffffffff810470b6>] warn_slowpath_fmt+0x46/0x50
>  [<ffffffff812d3a5e>] debug_print_object+0x8e/0xb0
>  [<ffffffff81bd8810>] ? hci_cmd_timer+0x0/0x60
>  [<ffffffff812d4685>] debug_check_no_obj_freed+0x125/0x230
>  [<ffffffff810f1063>] ? check_object+0xb3/0x2b0
>  [<ffffffff810f3630>] kfree+0x150/0x190
>  [<ffffffff81be4d06>] ? bt_host_release+0x16/0x20
>  [<ffffffff81be4d06>] bt_host_release+0x16/0x20
>  [<ffffffff813a1907>] device_release+0x27/0xa0
>  [<ffffffff812c519c>] kobject_release+0x4c/0xa0
>  [<ffffffff812c5150>] ? kobject_release+0x0/0xa0
>  [<ffffffff812c61f6>] kref_put+0x36/0x70
>  [<ffffffff812c4d37>] kobject_put+0x27/0x60
>  [<ffffffff813a21f7>] put_device+0x17/0x20
>  [<ffffffff81bda4f9>] hci_free_dev+0x29/0x30
>  [<ffffffff81928be6>] vhci_release+0x36/0x70
>  [<ffffffff810fb366>] fput+0xd6/0x1f0
>  [<ffffffff810f8fe6>] filp_close+0x66/0x90
>  [<ffffffff810f90a9>] sys_close+0x99/0xf0
>  [<ffffffff81d4c96b>] system_call_fastpath+0x16/0x1b
> 
> That timer was introduced with commit 6bd32326cda(Bluetooth: Use
> proper timer for hci command timout)
> 
> Timer seems to be running when the thing is closed. Removing the timer
> unconditionally fixes the problem. And yes, it needs to be fixed
> before the HCI_UP check.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  net/bluetooth/hci_core.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6/net/bluetooth/hci_core.c
> ===================================================================
> --- linux-2.6.orig/net/bluetooth/hci_core.c
> +++ linux-2.6/net/bluetooth/hci_core.c
> @@ -584,6 +584,9 @@ static int hci_dev_do_close(struct hci_d
>  	hci_req_cancel(hdev, ENODEV);
>  	hci_req_lock(hdev);
>  
> +	/* Stop timer, it might be running */
> +	del_timer_sync(&hdev->cmd_timer);
> +
>  	if (!test_and_clear_bit(HCI_UP, &hdev->flags)) {
>  		hci_req_unlock(hdev);
>  		return 0;
> @@ -623,7 +626,6 @@ static int hci_dev_do_close(struct hci_d
>  
>  	/* Drop last sent command */
>  	if (hdev->sent_cmd) {
> -		del_timer_sync(&hdev->cmd_timer);
>  		kfree_skb(hdev->sent_cmd);
>  		hdev->sent_cmd = NULL;
>  	}

Yes, this fixes the warning.

Tested-by: Ingo Molnar <mingo@elte.hu>

Thanks,

	Ingo
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