From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62957C4338F for ; Tue, 27 Jul 2021 09:12:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CF1B610CC for ; Tue, 27 Jul 2021 09:12:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236068AbhG0JMU (ORCPT ); Tue, 27 Jul 2021 05:12:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:56236 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235979AbhG0JMT (ORCPT ); Tue, 27 Jul 2021 05:12:19 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4C55F610CC; Tue, 27 Jul 2021 09:12:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1627377139; bh=47pJ7L+Vmiz+cAtUNrK7JsDsvaJRy1SEn0A9VAOkBzg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sdnxWmBQvaVnhMLoibq4sphOAmlI154NazNGjwc1b6KOl15VAXFVcQLCP63a1n92O zlIG1poPTR6RCral3U6l8Ii6ThD544tttxHFKUTckzT8TwY1sSTOEaduHkTr5uXoDr XHPbpRtMN/t+ldg398NZV5OiU7BilwAYMzZ05+I4= Date: Tue, 27 Jul 2021 11:12:17 +0200 From: "gregkh@linuxfoundation.org" To: Guido Kiener Cc: "qiang.zhang@windriver.com" , "stern@rowland.harvard.edu" , "dave penkler (dpenkler@gmail.com)" , "linux-usb@vger.kernel.org" Subject: Re: [PATCH v2] USB: usbtmc: Fix RCU stall warning Message-ID: References: <7ad985430b1e4ddcb642001f4dc8be84@rohde-schwarz.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7ad985430b1e4ddcb642001f4dc8be84@rohde-schwarz.com> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, Jul 27, 2021 at 07:56:27AM +0000, Guido Kiener wrote: > > > From: Qiang.zhang> > > > rcu: INFO: rcu_preempt self-detected stall on CPU > > > rcu: 1-...!: (2 ticks this GP) idle=d92/1/0x4000000000000000 > > > softirq=25390/25392 fqs=3 > > > (t=12164 jiffies g=31645 q=43226) > > > rcu: rcu_preempt kthread starved for 12162 jiffies! g31645 f0x0 > > > RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 > > > rcu: Unless rcu_preempt kthread gets sufficient CPU time, > > > OOM is now expected behavior. > > > rcu: RCU grace-period kthread stack dump: > > > task:rcu_preempt state:R running task > > > ........... > > > usbtmc 3-1:0.0: unknown status received: -71 usbtmc 3-1:0.0: unknown > > > status > > > received: -71 usbtmc 3-1:0.0: unknown status received: -71 usbtmc 3-1:0.0: > > > unknown status received: -71 usbtmc 3-1:0.0: unknown status received: > > > -71 usbtmc > > > 3-1:0.0: unknown status received: -71 usbtmc 3-1:0.0: unknown status > > > received: -71 usbtmc 3-1:0.0: unknown status received: -71 usbtmc > > > 3-1:0.0: usb_submit_urb > > > failed: -19 > > > > > > The function usbtmc_interrupt() resubmits urbs when the error status > > > of an urb is - EPROTO. In systems using the dummy_hcd usb controller > > > this can result in endless interrupt loops when the usbtmc device is disconnected > > from the host system. > > > > > > Since host controller drivers already try to recover from transmission > > > errors, there is no need to resubmit the urb or try other solutions to repair the error > > situation. > > > > > > In case of errors the INT pipe just stops to wait for further packets. > > > > > > Fixes: dbf3e7f654c0 ("Implement an ioctl to support the USMTMC-USB488 > > > READ_STATUS_BYTE operation") > > > Cc: stable@vger.kernel.org > > > Reported-by: syzbot+e2eae5639e7203360018@syzkaller.appspotmail.com > > > Signed-off-by: Qiang.zhang > > > --- > > > v1->v2: > > > Add fixes and stable tags, modify description information. > > > > > > drivers/usb/class/usbtmc.c | 9 +-------- > > > 1 file changed, 1 insertion(+), 8 deletions(-) > > > > > > diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c > > > index > > > 74d5a9c5238a..73f419adce61 100644 > > > --- a/drivers/usb/class/usbtmc.c > > > +++ b/drivers/usb/class/usbtmc.c > > > @@ -2324,17 +2324,10 @@ static void usbtmc_interrupt(struct urb *urb) > > > dev_err(dev, "overflow with length %d, actual length is %d\n", > > > data->iin_wMaxPacketSize, urb->actual_length); > > > fallthrough; > > > - case -ECONNRESET: > > > - case -ENOENT: > > > - case -ESHUTDOWN: > > > - case -EILSEQ: > > > - case -ETIME: > > > - case -EPIPE: > > > + default: > > > /* urb terminated, clean up */ > > > dev_dbg(dev, "urb terminated, status: %d\n", status); > > > return; > > > - default: > > > - dev_err(dev, "unknown status received: %d\n", status); > > > } > > > exit: > > > rv = usb_submit_urb(urb, GFP_ATOMIC); > > > -- > > > 2.25.1 > > > > The patch looks good to me and is tested on my machine. > > > > Ack-by: Guido Kiener > > > > -Guido > > Greg, > > Can you please add the patch https://patchwork.kernel.org/project/linux-usb/list/?series=520033 > Dave, Alan, and I are ok with the patch. Relax, I will get to it :)