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Sun, 22 Mar 2026 22:34:33 -0700 (PDT) Date: Sun, 22 Mar 2026 22:34:30 -0700 From: Dmitry Torokhov To: Mikhail Gavrilov 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-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Mar 23, 2026 at 10:17:01AM +0500, Mikhail Gavrilov wrote: > On Mon, Mar 23, 2026 at 7:47 AM Dmitry Torokhov > wrote: > > > > Thank you for the patch, it looks solid, however I wonder if creating a > > separate "state_lock" spinlock would not be better than reusing > > requests_lock? > > Hi Dmitry, > > Thank you for the review. > > A separate spinlock would certainly be cleaner from a naming > perspective. One thing I'd like to note though: the current > approach of reusing requests_lock has the benefit of atomically > checking state and queueing the event in uinput_request_send(), > and atomically changing state and flushing requests in > uinput_destroy_device(). With a separate state_lock these become > two independent locks, so the ordering between them would need to > be defined. Hmm, I am not sure I see the issue. We are not going to change state back to UIST_CREATED until after uinput_destroy_device() returns so we will not submit more requests... What am I missing? Thanks. -- Dmitry