From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f69.google.com (mail-pj1-f69.google.com [209.85.216.69]) (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 A59FA36C598 for ; Thu, 23 Apr 2026 16:05:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776960339; cv=none; b=Ztl9D9Ip+Xpen0alP903whgAFLe5O8bNFm7NM7AtcqpcEFKNG0hfLi8iTLBQI73tm5Tr20banOS1jhzRJPCu1W7vsHgOTq3h4EaeAUYSPA7iOHlTblJvUorM9sx9rIcvJYt6LO+9bkeOyaVcgW0hrMbAFrtrXvzb8jorDIMiYl4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776960339; c=relaxed/simple; bh=iIWp6i9FcI76CiqwMJMv/Ax78ggiIRTJCmzS9UPQ4VE=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To:Cc: Content-Type; b=l2QrifezHNRNPwgDWQshjPZstmCXrWFTVHwqZ63nWI7oxmcNapY0TgDiKLWDuZBDXfayrrSQfYn3tg7Tc077Z50RzVd3XvwH/twXNWvRWTgoFftL60vgOGXkuUtCh6XqChsaF9JnnJCyXiwsF2aN/tatjnl+qY0Jy3Ppwg0qtUQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.216.69 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-pj1-f69.google.com with SMTP id 98e67ed59e1d1-358e425c261so8217898a91.3 for ; Thu, 23 Apr 2026 09:05:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776960338; x=1777565138; h=cc:to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=e3HadXVXm8Vbqa9+RiiKD2XKixY1TBNX5MNBCpPCreo=; b=fskQKOnrWkcr9T9v0ynRmOQjRFRO1vk91WCNgZPCwWNeOgWub5JC6wu/1rJkVxbXbo LJQVD5VWnsG6zppd2616kGxH0ku4E5PaVMz32RatuIBqH8g0tdYpOXn5H1K8AewC1MIo varL8kEuL4TGZum2CIKhST6yYNHIpY0dHLh1s386vkvvYmn0vUq0BBeiWM8zoDcVGtST ygLCeymXX/ptQHWVYeWF1kZwJ6xez5i5KD+WSRPo+2mJbWCYFiCjsiUIpaWzAAIBPwKh d0mEboa+enV16eNolHoHTzUqgHq8E8JaioXjUZKFioQFxxcGTq+fOooWRhIcYELWI+Im yMSg== X-Forwarded-Encrypted: i=1; AFNElJ89u7BGbbUUnzbmiOc0TF95QOgo1oXDh8WWEjNjwj3la7nFsPMPfijeedkArj5ye3nktgOjDtEdfe5hy4s=@vger.kernel.org X-Gm-Message-State: AOJu0YxYgWzoKqHtowBv+Yk+L63BnVvhv1sTvSTYt6RakJzRvngpz6tF 8a/gahmSYFX35iqJgWO1z0roIkpXWVtDg1zkR28Alda9A8p6qH0D9ymOe/V6OAN1ofRhHxzacWL +duaeC3SXLpoz+IY7rplzisBlS7Czhf6QzfXkfN9SlIMGaM5AulGM4RBy4W4= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a17:90b:2ec7:b0:35f:c0d7:ac54 with SMTP id 98e67ed59e1d1-3614041aa7amr28878440a91.12.1776960338100; Thu, 23 Apr 2026 09:05:38 -0700 (PDT) Date: Thu, 23 Apr 2026 09:05:38 -0700 In-Reply-To: X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69ea4352.a00a0220.17a17.0041.GAE@google.com> Subject: Re: INFO: rcu detected stall in dummy_timer (3) From: syzbot To: stern@rowland.harvard.edu Cc: linux-usb@vger.kernel.org, stern@rowland.harvard.edu, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" > I'm revisiting an old syzbot bug caused by a tight resubmit loop, this > one in mceusb. The bug was fixed by commit 476db72e5219 ("media: > mceusb: return without resubmitting URB in case of -EPROTO error."), but > I want to try fixing it a different way, by changing dummy-hcd. > > This is a preliminary test, to make sure the bug can still be triggered. > The patch below doesn't do anything -- yet! > > Alan Stern > > #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git 811d22141369 This bug is already marked as fixed. No point in 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 > @@ -231,6 +231,7 @@ struct urbp { > struct list_head urbp_list; > struct sg_mapping_iter miter; > u32 miter_started; > + int missing_ep_delay; > }; > > > @@ -1275,6 +1276,7 @@ static int dummy_urb_enqueue( > return -ENOMEM; > urbp->urb = urb; > urbp->miter_started = 0; > + urbp->missing_ep_delay = 80; /* Microframes -> 10 ms */ > > dum_hcd = hcd_to_dummy_hcd(hcd); > spin_lock_irqsave(&dum_hcd->dum->lock, flags); > @@ -1863,6 +1865,8 @@ restart: > address |= USB_DIR_IN; > ep = find_endpoint(dum, address); > if (!ep) { > +// if (--urbp->missing_ep_delay > 0) > +// continue; > /* set_configuration() disagreement */ > dev_dbg(dummy_dev(dum_hcd), > "no ep configured for urb %p\n",