From: Alan Stern <stern@rowland.harvard.edu>
To: "Zhang, Qiang" <Qiang.Zhang@windriver.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
syzbot <syzbot+e2eae5639e7203360018@syzkaller.appspotmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"guido.kiener@rohde-schwarz.com" <guido.kiener@rohde-schwarz.com>,
"dpenkler@gmail.com" <dpenkler@gmail.com>,
"lee.jones@linaro.org" <lee.jones@linaro.org>,
USB list <linux-usb@vger.kernel.org>,
"bp@alien8.de" <bp@alien8.de>,
"dwmw@amazon.co.uk" <dwmw@amazon.co.uk>,
"hpa@zytor.com" <hpa@zytor.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"luto@kernel.org" <luto@kernel.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"syzkaller-bugs@googlegroups.com"
<syzkaller-bugs@googlegroups.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"x86@kernel.org" <x86@kernel.org>
Subject: Re: [syzbot] INFO: rcu detected stall in tx
Date: Mon, 28 Jun 2021 10:17:51 -0400 [thread overview]
Message-ID: <20210628141751.GB656159@rowland.harvard.edu> (raw)
In-Reply-To: <BL1PR11MB5478572825796B0F04E1E1FDFF039@BL1PR11MB5478.namprd11.prod.outlook.com>
On Mon, Jun 28, 2021 at 06:38:37AM +0000, Zhang, Qiang wrote:
>
>
> ________________________________________
> From: Dmitry Vyukov <dvyukov@google.com>
> Sent: Monday, 19 April 2021 15:27
> To: syzbot; Greg Kroah-Hartman; guido.kiener@rohde-schwarz.com; dpenkler@gmail.com; lee.jones@linaro.org; USB list
> Cc: bp@alien8.de; dwmw@amazon.co.uk; hpa@zytor.com; linux-kernel@vger.kernel.org; luto@kernel.org; mingo@redhat.com; syzkaller-bugs@googlegroups.com; tglx@linutronix.de; x86@kernel.org
> Subject: Re: [syzbot] INFO: rcu detected stall in tx
>
> [Please note: This e-mail is from an EXTERNAL e-mail address]
>
> On Mon, Apr 19, 2021 at 9:19 AM syzbot
> <syzbot+e2eae5639e7203360018@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: 50987bec Merge tag 'trace-v5.12-rc7' of git://git.kernel.o..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1065c5fcd00000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=398c4d0fe6f66e68
> > dashboard link: https://syzkaller.appspot.com/bug?extid=e2eae5639e7203360018
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+e2eae5639e7203360018@syzkaller.appspotmail.com
> >
> > usbtmc 5-1:0.0: unknown status received: -71
> > usbtmc 3-1:0.0: unknown status received: -71
> > usbtmc 5-1:0.0: unknown status received: -71
>
> >The log shows an infinite stream of these before the stall, so I
> >assume it's an infinite loop in usbtmc.
> >+usbtmc maintainers
> >
> >[ 370.171634][ C0] usbtmc 6-1:0.0: unknown status received: >-71
> >[ 370.177799][ C1] usbtmc 3-1:0.0: unknown status received: >-71
> This seems like a long time in the following cycle, when the callback function usbtmc_interrupt() find unknown status error, it will submit urb again. the urb may be insert urbp_list.
> due to the dummy_timer() be called in bh-disable.
> This will result in the RCU reading critical area not exiting for a long time (note: bh_disable/enable, preempt_disable/enable is regarded as the RCU critical reading area ), and prevent rcu_preempt kthread be schedule and running.
> Whether to return directly when we find the urb status is unknown error?
Yes.
> diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
> index 74d5a9c5238a..39d44339c03f 100644
> --- a/drivers/usb/class/usbtmc.c
> +++ b/drivers/usb/class/usbtmc.c
> @@ -2335,6 +2335,7 @@ static void usbtmc_interrupt(struct urb *urb)
> return;
> default:
> dev_err(dev, "unknown status received: %d\n", status);
> + return;
> }
> exit:
> rv = usb_submit_urb(urb, GFP_ATOMIC);
This is the right thing to do. In fact, you should also change the code
above this. There's no real need for special handling of the
-ECONNRESET, -ENOENT, ..., -EPIPE codes, since the driver will do the
same thing no matter what the code is.
Alan Stern
next prev parent reply other threads:[~2021-06-28 14:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <000000000000a9b79905c04e25a0@google.com>
2021-04-19 7:27 ` [syzbot] INFO: rcu detected stall in tx Dmitry Vyukov
2021-06-28 6:38 ` Zhang, Qiang
2021-06-28 14:17 ` Alan Stern [this message]
2021-06-27 20:20 ` syzbot
2021-09-04 7:55 ` syzbot
2021-05-20 21:25 Guido Kiener
2021-05-21 1:24 ` Alan Stern
2021-05-21 22:17 ` guido
2021-05-22 2:13 ` Alan Stern
-- strict thread matches above, loose matches on Subject: below --
2021-05-19 16:14 Re: Re: Re: Re: " Guido Kiener
2021-05-19 17:35 ` Alan Stern
2021-05-19 19:38 ` Thinh Nguyen
2021-05-20 2:01 ` Alan Stern
2021-05-20 20:30 ` Thinh Nguyen
2021-05-24 15:18 ` Mathias Nyman
2021-05-24 18:55 ` Alan Stern
2021-05-24 19:23 ` Thinh Nguyen
2021-05-24 22:16 ` Mathias Nyman
2021-05-24 22:48 ` Thinh Nguyen
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