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Wed, 11 Mar 2026 10:47:28 -0700 (PDT) Received: from primary-ws.local ([188.234.148.119]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-38a67e5ed6esm4360351fa.23.2026.03.11.10.47.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2026 10:47:28 -0700 (PDT) Message-ID: Subject: Re: [PATCH] Input: uinput - fix circular locking dependency with ff-core From: mikhail.v.gavrilov@gmail.com To: dmitry.torokhov@gmail.com Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 11 Mar 2026 22:47:25 +0500 In-Reply-To: <20260228223628.472208-1-mikhail.v.gavrilov@gmail.com> References: <20260228223628.472208-1-mikhail.v.gavrilov@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.59.3 (3.59.3-1.fc45) Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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): >=20 > =C2=A0 ff->mutex -> udev->mutex -> input_mutex -> dev->mutex -> ff->mutex >=20 > The cycle is caused by four lock acquisition paths: >=20 > 1. ff upload: input_ff_upload() holds ff->mutex and calls > =C2=A0=C2=A0 uinput_dev_upload_effect() -> uinput_request_submit() -> > =C2=A0=C2=A0 uinput_request_send(), which acquires udev->mutex. >=20 > 2. device create: uinput_ioctl_handler() holds udev->mutex and calls > =C2=A0=C2=A0 uinput_create_device() -> input_register_device(), which acq= uires > =C2=A0=C2=A0 input_mutex. >=20 > 3. device register: input_register_device() holds input_mutex and > =C2=A0=C2=A0 calls kbd_connect() -> input_register_handle(), which acquir= es > =C2=A0=C2=A0 dev->mutex. >=20 > 4. evdev release: evdev_release() calls input_flush_device() under > =C2=A0=C2=A0 dev->mutex, which calls input_ff_flush() acquiring ff->mutex= . >=20 >=20 >=20 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? --=20 Best Regards, Mike Gavrilov.