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Wed, 11 Mar 2026 10:50:34 -0700 (PDT) Received: from google.com ([2a00:79e0:2ebe:8:53e0:5b17:5211:b0f4]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2be8aa4eb92sm3729992eec.22.2026.03.11.10.50.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2026 10:50:33 -0700 (PDT) Date: Wed, 11 Mar 2026 10:50:18 -0700 From: Dmitry Torokhov To: mikhail.v.gavrilov@gmail.com Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Input: uinput - fix circular locking dependency with ff-core Message-ID: References: <20260228223628.472208-1-mikhail.v.gavrilov@gmail.com> Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Mar 11, 2026 at 10:47:25PM +0500, mikhail.v.gavrilov@gmail.com wrote: > On Sun, 2026-03-01 at 03:36 +0500, Mikhail Gavrilov wrote: > > A lockdep circular locking dependency warning can be triggered > > reproducibly when using a force-feedback gamepad with uinput (for > > example, playing ELDEN RING under Wine with a Flydigi Vader 5 > > controller): > > > >   ff->mutex -> udev->mutex -> input_mutex -> dev->mutex -> ff->mutex > > > > The cycle is caused by four lock acquisition paths: > > > > 1. ff upload: input_ff_upload() holds ff->mutex and calls > >    uinput_dev_upload_effect() -> uinput_request_submit() -> > >    uinput_request_send(), which acquires udev->mutex. > > > > 2. device create: uinput_ioctl_handler() holds udev->mutex and calls > >    uinput_create_device() -> input_register_device(), which acquires > >    input_mutex. > > > > 3. device register: input_register_device() holds input_mutex and > >    calls kbd_connect() -> input_register_handle(), which acquires > >    dev->mutex. > > > > 4. evdev release: evdev_release() calls input_flush_device() under > >    dev->mutex, which calls input_ff_flush() acquiring ff->mutex. > > > > > > > Hi Dmitry, > > Friendly ping on this patch. It fixes a reproducible lockdep circular > dependency warning in uinput with force-feedback gamepads under > Wine/Proton, tested on 7.0-rc1. > > I realize I should have included: > > Fixes: ff462551235d ("Input: uinput - switch to the new FF > interface") > Cc: stable@vger.kernel.org > > Should I resend as v2 with these tags, or can you add them when > applying? Sorry I need a bit more time to evaluate the patch. I think what you proposed makes sense, just give me a couple more days. If there are no changes needed I can add necessary tags on my end. Thanks. -- Dmitry