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[95.235.102.55]) by smtp.gmail.com with ESMTPSA id k66-20020a1ca145000000b003a2fdde48d1sm2131090wme.25.2022.07.21.07.45.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Jul 2022 07:45:32 -0700 (PDT) From: "Fabio M. De Francesco" To: Tetsuo Handa Cc: Dmitry Torokhov , Johan Hovold , syzkaller-bugs@googlegroups.com, rydberg@bitmath.org, syzkaller-bugs@googlegroups.com, syzbot , linux-input@vger.kernel.org Subject: Re: [syzbot] INFO: task hung in __input_unregister_device (4) Date: Thu, 21 Jul 2022 16:45:31 +0200 Message-ID: <8106256.T7Z3S40VBb@opensuse> In-Reply-To: References: <000000000000ed47a705e2cbd347@google.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org On gioved=C3=AC 21 luglio 2022 13:11:44 CEST Tetsuo Handa wrote: > Hello. >=20 > syzbot is reporting that iforce_close() from input_close_device() from > joydev_close_device() from joydev_release() forever sleeps at >=20 > wait_event_interruptible(iforce->wait, > !test_bit(IFORCE_XMIT_RUNNING, iforce- >xmit_flags)); >=20 > with dev->mutex held, which in turn prevents input_disconnect_device()=20 from > __input_unregister_device() from input_unregister_device() from > iforce_usb_disconnect() from setting dev->going_away =3D true. >=20 > We somehow need to wake up this wait_event_interruptible() in=20 iforce_close() > if iforce_usb_disconnect() is in progress. But iforce_usb_disconnect()=20 does > not manipulate flags for waking up this wait_event_interruptible(). How=20 can > we wake up this wait_event_interruptible()? >=20 I haven't been following this thread, except reading only this message. It= =20 may well be I'm saying something which is not suited for solving your=20 problem. If it can be fixed, as you said, by a simple notification to=20 wait_event_interruptible(), why not changing iforce_usb_disconnect() the=20 following way? static void iforce_usb_disconnect(struct usb_interface *intf) { struct iforce_usb *iforce_usb =3D usb_get_intfdata(intf); usb_set_intfdata(intf, NULL); __set_bit(IFORCE_XMIT_RUNNING, iforce_usb->iforce.xmit_flags); wake_up(&iforce_usb->iforce.wait); input_unregister_device(iforce_usb->iforce.dev); usb_free_urb(iforce_usb->irq); usb_free_urb(iforce_usb->out); kfree(iforce_usb); } I am sorry if I'm overlooking anything, especially because I'm entering=20 this thread without reading the other messages and so without knowing the=20 whole context. Furthermore I haven't even test-compiled these changes :-( Thanks, =46abio