From: fx IWATA NOBUO <Nobuo.Iwata@fujixerox.co.jp>
To: Andrey Konovalov <andreyknvl@google.com>,
        Shuah Khan <shuahkh@osg.samsung.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Valentina Manea <valentina.manea.m@gmail.com>,
        Shuah Khan <shuah@kernel.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] usbip: fix warning in vhci_hcd_probe/lockdep_init_map
Thread-Topic: [PATCH] usbip: fix warning in vhci_hcd_probe/lockdep_init_map
Thread-Index: AQHSTzHDm8PVADuBJkahYzYll8fkK6D5xhOAgAEN8ACAAneiwA==
Date: Thu, 8 Dec 2016 02:15:50 +0000
Message-ID: <HK2PR06MB156911C1C5FB17C5CC386B9EB9840@HK2PR06MB1569.apcprd06.prod.outlook.com>
References: <20161205195638.7005-1-shuahkh@osg.samsung.com>
 <4a3b7e4f-6b5c-d9e8-f26c-1286d4e1f630@osg.samsung.com>
 <CAAeHK+ycHQS7Hbamt-A3MHORGrvH8UmW7KdiEA==V1z8wdnwEA@mail.gmail.com>
In-Reply-To: <CAAeHK+ycHQS7Hbamt-A3MHORGrvH8UmW7KdiEA==V1z8wdnwEA@mail.gmail.com>
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Dear Shuah,

I'm afraid there's one thing I have concerned.

I think it's better to move sysfs_attr_init() before
status->attr.attr.name = status->name;

Best Regards,

nobuo.iwata
//
> -----Original Message-----
> From: linux-usb-owner@vger.kernel.org
> [mailto:linux-usb-owner@vger.kernel.org] On Behalf Of Andrey Konovalov
> Sent: Tuesday, December 06, 2016 9:07 PM
> To: Shuah Khan
> Cc: Greg Kroah-Hartman; Valentina Manea; Shuah Khan;
> linux-usb@vger.kernel.org; LKML
> Subject: Re: [PATCH] usbip: fix warning in vhci_hcd_probe/lockdep_init_map
> 
> On Mon, Dec 5, 2016 at 9:00 PM, Shuah Khan <shuahkh@osg.samsung.com> wrote:
> > Hi Andrey,
> >
> > On 12/05/2016 12:56 PM, Shuah Khan wrote:
> >> vhci_hcd calls sysfs_create_group() with dynamically allocated sysfs
> >> attributes triggering the lock-class key not persistent warning. Call
> >> sysfs_attr_init() for dynamically allocated sysfs attributes to fix it.
> >>
> >> vhci_hcd vhci_hcd: USB/IP Virtual Host Controller vhci_hcd vhci_hcd:
> >> new USB bus registered, assigned bus number 2
> >> BUG: key ffff88006a7e8d18 not in .data!
> >> ------------[ cut here ]------------
> >> WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:3131
> >> lockdep_init_map+0x60c/0x770
> >> DEBUG_LOCKS_WARN_ON(1)[    1.567044] Modules linked in:
> >> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.9.0-rc7+ #58 Hardware
> >> name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> >>  ffff88006bce6eb8 ffffffff81f96c8a ffffffff00000a02 1ffff1000d79cd6a
> >>  ffffed000d79cd62 000000046bce6ed8 0000000041b58ab3 ffffffff8598af40
> >>  ffffffff81f969f8 0000000000000000 0000000041b58ab3 0000000000000200
> >> Call Trace:
> >>  [<     inline     >] __dump_stack lib/dump_stack.c:15
> >>  [<ffffffff81f96c8a>] dump_stack+0x292/0x398 lib/dump_stack.c:51
> >> [<ffffffff812b808f>] __warn+0x19f/0x1e0 kernel/panic.c:550
> >> [<ffffffff812b8195>] warn_slowpath_fmt+0xc5/0x110 kernel/panic.c:565
> >> [<ffffffff813f3efc>] lockdep_init_map+0x60c/0x770
> >> kernel/locking/lockdep.c:3131  [<ffffffff819e43d4>]
> >> __kernfs_create_file+0x114/0x2a0 fs/kernfs/file.c:954
> [<ffffffff819e68f5>] sysfs_add_file_mode_ns+0x225/0x520
> fs/sysfs/file.c:305
> >>  [<     inline     >] create_files fs/sysfs/group.c:64
> >>  [<ffffffff819e8a89>] internal_create_group+0x239/0x8f0
> >> fs/sysfs/group.c:134  [<ffffffff819e915f>]
> >> sysfs_create_group+0x1f/0x30 fs/sysfs/group.c:156
> >> [<ffffffff8323de24>] vhci_start+0x5b4/0x7a0
> >> drivers/usb/usbip/vhci_hcd.c:978  [<ffffffff82c907ca>]
> >> usb_add_hcd+0x8da/0x1c60 drivers/usb/core/hcd.c:2867
> >> [<ffffffff8323bc57>] vhci_hcd_probe+0x97/0x130
> >> drivers/usb/usbip/vhci_hcd.c:1103
> >>  ---
> >>  ---
> >> ---[ end trace c33c7b202cf3aac8 ]---
> >>
> >> Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
> >> Reported-by: Andrey Konovalov <andreyknvl@google.com>
> >
> > Here is the fix. Fixed the warning I reproduced on my system.
> > Let me know if it works for you.
> 
> Hi Shuah,
> 
> This fixes the warning I've been seeing.
> 
> Thanks!
> 
> >
> > thanks,
> > -- Shuah
> >
> >> ---
> >>  drivers/usb/usbip/vhci_sysfs.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/drivers/usb/usbip/vhci_sysfs.c
> >> b/drivers/usb/usbip/vhci_sysfs.c index c404017..b96e5b1 100644
> >> --- a/drivers/usb/usbip/vhci_sysfs.c
> >> +++ b/drivers/usb/usbip/vhci_sysfs.c
> >> @@ -361,6 +361,7 @@ static void set_status_attr(int id)
> >>       status->attr.attr.name = status->name;
> >>       status->attr.attr.mode = S_IRUGO;
> >>       status->attr.show = status_show;
> >> +     sysfs_attr_init(&status->attr.attr);
> >>  }
> >>
> >>  static int init_status_attrs(void)
> >>
> >
> --
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