From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f174.google.com (mail-qk1-f174.google.com [209.85.222.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6504314AA9 for ; Mon, 14 Oct 2024 16:14:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728922489; cv=none; b=Fjw7KEtMXJsR9suj6GWmoF7UA4dO5fhKe2Oaej1P3YtsmIj+J86S/TA94bNpTBaijTHCOQ+UFTuy89493cbOkb+XTS8i/riqAOft4PMlER9Q646AofJij3cN0GA5+uu62ygbb74zizY8ZksyyoOB7VRTd9Ckt4rQR/xBGFWGIXM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728922489; c=relaxed/simple; bh=d+i7rz0v/lYhzDT8S7U2kztGhbofW2nOLWBFt6tMbxo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qwJtmwm5fxCiBWLhk+QDkFbJVELPTNgSmZAaSSaGG5SLXBB6779PW1ZjUdEXd6UJSfEXzuZjFHpAYNaquQWX7E8rcg7+seVoGEQnq/JcSCprxx3h/U1Ak3NPVGCM3bGCo6dynUV68VqONERxkCUYUI89zKP3Qe+3Y5ohYxbKrfA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rowland.harvard.edu; spf=fail smtp.mailfrom=g.harvard.edu; dkim=pass (2048-bit key) header.d=rowland.harvard.edu header.i=@rowland.harvard.edu header.b=fL+jI8Ft; arc=none smtp.client-ip=209.85.222.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rowland.harvard.edu Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=g.harvard.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=rowland.harvard.edu header.i=@rowland.harvard.edu header.b="fL+jI8Ft" Received: by mail-qk1-f174.google.com with SMTP id af79cd13be357-7afcf96affaso229436985a.0 for ; Mon, 14 Oct 2024 09:14:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rowland.harvard.edu; s=google; t=1728922486; x=1729527286; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=8+z5rpFItk6hQgTy6bORhF+SgqBTinir6Gfegnb3yHE=; b=fL+jI8FtLRh458X5XbkE/GpoaSVmrlshbFy8qRziGZm6qV/D5YLOyu3tTFiTsBcjta yihlPsIhM4kleN2Q5zxdnRWr31RNdk8NK1olrIdRt0TXPReJvENkjQMeSykWW3ZOrcP5 nmTKaoZ3Q5Gchn55uSL+WVCckI1zgDKeI6nq1TY56hfNKGK+aiwri6d5ShEhVnt/H8WT 6wz4AvlBLnISKUcXmCEbsVmSAF1UguiBxF1siwEkTmoJqYCQB8Dp1lVBrdRNW9PkfMNT 4tXDAQhayJ2u3ySkm5w5OCvIr78zHWcGTulgr0VHCIIOgKJIJxwGX8LbExKqQHsnfvqu O0aw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728922486; x=1729527286; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=8+z5rpFItk6hQgTy6bORhF+SgqBTinir6Gfegnb3yHE=; b=BvM+MtBjlMJSiH3beeEDxvtM2aWHw44rFlZChEP00rgteYDDt17J8nhTlUmK6qedjE LlVOv6zHjfEixksp55FtQkMhP/QCWmmN3vyb5aqVXbwlVXrJECAwwOWfrChprP7YMMIh OFWY0wtQhbkfEF1OeP9wShPIMnxJEyFwO3ASg/S++Ws61ig5+ee+NmiYBsI5FsiMb2df O9q9wwak8Wtq60DVe65nKLcnlIabRTxjGiid9IEFk5btWDcpc2GJEsE4waMQiRkadFWw GYjuQizprMbLZCkfgacrQE6jP8QN9o8ROE5uFwAZbdsbS6Yo+WEegvjAewFXgCi40tuQ r2Cw== X-Gm-Message-State: AOJu0Yw7q3OjwEvueDnfQzFqoK6X8E3V6ncHidl7biXgzI07K19xEbl/ T+Iri5zLlGb1fiGRXeCNECTTXrIRyYjVve/cCEuG8GTZnHsOKrtRBXYwfIaiOFT2RZoypqT/qqI = X-Google-Smtp-Source: AGHT+IFiWvyQHPw52VbxejgOs1jzzUybj5lACemxxUJIvDLtI0pYTAU28T0GKhme31JWd+fsvKQJrQ== X-Received: by 2002:a05:620a:24c9:b0:7b1:10ba:2ac0 with SMTP id af79cd13be357-7b11a37c2acmr1955757685a.35.1728922486285; Mon, 14 Oct 2024 09:14:46 -0700 (PDT) Received: from rowland.harvard.edu ([2601:19b:681:fd10::c666]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7b1148de09fsm436477685a.49.2024.10.14.09.14.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Oct 2024 09:14:45 -0700 (PDT) Date: Mon, 14 Oct 2024 12:14:43 -0400 From: Alan Stern To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [usb?] INFO: task hung in usb_port_suspend Message-ID: References: <670c7aaa.050a0220.3e960.004e.GAE@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <670c7aaa.050a0220.3e960.004e.GAE@google.com> On Sun, Oct 13, 2024 at 06:58:02PM -0700, syzbot wrote: > Hello, > > syzbot has tested the proposed patch and the reproducer did not trigger any issue: It seems that the problem occurs when the timer isn't active in spite of the fact that the root hub is running and there are URBs queued. But this shouldn't happen; I need to find the reason why it does and not just work around it. First make sure that it really is the cause. Alan Stern #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing Index: usb-devel/drivers/usb/gadget/udc/dummy_hcd.c =================================================================== --- usb-devel.orig/drivers/usb/gadget/udc/dummy_hcd.c +++ usb-devel/drivers/usb/gadget/udc/dummy_hcd.c @@ -50,7 +50,7 @@ #define POWER_BUDGET 500 /* in mA; use 8 for low-power port testing */ #define POWER_BUDGET_3 900 /* in mA */ -#define DUMMY_TIMER_INT_NSECS 125000 /* 1 microframe */ +#define DUMMY_INT_KTIME ns_to_ktime(125000) /* 1 microframe */ static const char driver_name[] = "dummy_hcd"; static const char driver_desc[] = "USB Host+Gadget Emulator"; @@ -257,6 +257,8 @@ struct dummy_hcd { unsigned active:1; unsigned old_active:1; unsigned resuming:1; + + bool alanflag; }; struct dummy { @@ -1301,10 +1303,12 @@ static int dummy_urb_enqueue( dum_hcd->next_frame_urbp = urbp; if (usb_pipetype(urb->pipe) == PIPE_CONTROL) urb->error_count = 1; /* mark as a new urb */ + dev_info(dummy_dev(dum_hcd), "Enqueue %p type %d\n", urb, + usb_pipetype(urb->pipe)); /* kick the scheduler, it'll do the rest */ if (!hrtimer_active(&dum_hcd->timer)) - hrtimer_start(&dum_hcd->timer, ns_to_ktime(DUMMY_TIMER_INT_NSECS), + hrtimer_start(&dum_hcd->timer, DUMMY_INT_KTIME, HRTIMER_MODE_REL_SOFT); done: @@ -1325,9 +1329,15 @@ static int dummy_urb_dequeue(struct usb_ rc = usb_hcd_check_unlink_urb(hcd, urb, status); if (!rc && dum_hcd->rh_state != DUMMY_RH_RUNNING && - !list_empty(&dum_hcd->urbp_list)) - hrtimer_start(&dum_hcd->timer, ns_to_ktime(0), HRTIMER_MODE_REL_SOFT); - + !list_empty(&dum_hcd->urbp_list)) { + dev_info(dummy_dev(dum_hcd), "Dequeue restart %p\n", urb); + hrtimer_start(&dum_hcd->timer, DUMMY_INT_KTIME, + HRTIMER_MODE_REL_SOFT); + } else { + dev_info(dummy_dev(dum_hcd), "Dequeue norestart: %d %p active %d\n", + rc, urb, hrtimer_active(&dum_hcd->timer)); + } + dum_hcd->alanflag = true; spin_unlock_irqrestore(&dum_hcd->dum->lock, flags); return rc; } @@ -1813,6 +1823,10 @@ static enum hrtimer_restart dummy_timer( /* look at each urb queued by the host side driver */ spin_lock_irqsave(&dum->lock, flags); + if (dum_hcd->alanflag) { + dum_hcd->alanflag = false; + dev_info(dummy_dev(dum_hcd), "Timer handler\n"); + } if (!dum_hcd->udev) { dev_err(dummy_dev(dum_hcd), @@ -1984,6 +1998,7 @@ return_urb: ep->already_seen = ep->setup_stage = 0; usb_hcd_unlink_urb_from_ep(dummy_hcd_to_hcd(dum_hcd), urb); + dev_info(dummy_dev(dum_hcd), "Giveback %p\n", urb); spin_unlock(&dum->lock); usb_hcd_giveback_urb(dummy_hcd_to_hcd(dum_hcd), urb, status); spin_lock(&dum->lock); @@ -1995,8 +2010,7 @@ return_urb: usb_put_dev(dum_hcd->udev); dum_hcd->udev = NULL; } else if (dum_hcd->rh_state == DUMMY_RH_RUNNING) { - /* want a 1 msec delay here */ - hrtimer_start(&dum_hcd->timer, ns_to_ktime(DUMMY_TIMER_INT_NSECS), + hrtimer_start(&dum_hcd->timer, DUMMY_INT_KTIME, HRTIMER_MODE_REL_SOFT); } @@ -2391,7 +2405,8 @@ static int dummy_bus_resume(struct usb_h dum_hcd->rh_state = DUMMY_RH_RUNNING; set_link_state(dum_hcd); if (!list_empty(&dum_hcd->urbp_list)) - hrtimer_start(&dum_hcd->timer, ns_to_ktime(0), HRTIMER_MODE_REL_SOFT); + hrtimer_start(&dum_hcd->timer, DUMMY_INT_KTIME, + HRTIMER_MODE_REL_SOFT); hcd->state = HC_STATE_RUNNING; } spin_unlock_irq(&dum_hcd->dum->lock);