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Mon, 29 Sep 2025 01:46:28 -0700 (PDT) Received: from localhost ([196.207.164.177]) by smtp.gmail.com with UTF8SMTPSA id ffacd0b85a97d-40fb72fb017sm17297267f8f.3.2025.09.29.01.46.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Sep 2025 01:46:27 -0700 (PDT) Date: Mon, 29 Sep 2025 11:46:24 +0300 From: Dan Carpenter To: oe-kbuild@lists.linux.dev, Mary Strodl , linux-kernel@vger.kernel.org Cc: lkp@intel.com, oe-kbuild-all@lists.linux.dev, linus.walleij@linaro.org, brgl@bgdev.pl, linux-gpio@vger.kernel.org, Mary Strodl Subject: Re: [PATCH v2 1/3] gpio: mpsse: use rcu to ensure worker is torn down Message-ID: <202509290823.hreUi6Tp-lkp@intel.com> Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250923133304.273529-2-mstrodl@csh.rit.edu> Hi Mary, kernel test robot noticed the following build warnings: https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Mary-Strodl/gpio-mpsse-use-rcu-to-ensure-worker-is-torn-down/20250923-214710 base: https://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux.git gpio/for-next patch link: https://lore.kernel.org/r/20250923133304.273529-2-mstrodl%40csh.rit.edu patch subject: [PATCH v2 1/3] gpio: mpsse: use rcu to ensure worker is torn down config: i386-randconfig-141-20250929 (https://download.01.org/0day-ci/archive/20250929/202509290823.hreUi6Tp-lkp@intel.com/config) compiler: gcc-12 (Debian 12.4.0-5) 12.4.0 If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot | Reported-by: Dan Carpenter | Closes: https://lore.kernel.org/r/202509290823.hreUi6Tp-lkp@intel.com/ New smatch warnings: drivers/gpio/gpio-mpsse.c:341 gpio_mpsse_poll() error: dereferencing freed memory 'worker' (line 342) drivers/gpio/gpio-mpsse.c:604 gpio_mpsse_disconnect() error: dereferencing freed memory 'worker' (line 605) vim +/worker +341 drivers/gpio/gpio-mpsse.c a14b0c5e3b0741 Mary Strodl 2025-09-23 304 static void gpio_mpsse_poll(struct work_struct *my_work) c46a74ff05c0ac Mary Strodl 2024-10-09 305 { c46a74ff05c0ac Mary Strodl 2024-10-09 306 unsigned long pin_mask, pin_states, flags; c46a74ff05c0ac Mary Strodl 2024-10-09 307 int irq_enabled, offset, err, value, fire_irq, c46a74ff05c0ac Mary Strodl 2024-10-09 308 irq, old_value[16], irq_type[16]; a14b0c5e3b0741 Mary Strodl 2025-09-23 309 struct mpsse_worker *worker; a14b0c5e3b0741 Mary Strodl 2025-09-23 310 struct mpsse_worker *my_worker = container_of(my_work, struct mpsse_worker, work); a14b0c5e3b0741 Mary Strodl 2025-09-23 311 struct mpsse_priv *priv = my_worker->priv; a14b0c5e3b0741 Mary Strodl 2025-09-23 312 struct list_head destructors = LIST_HEAD_INIT(destructors); c46a74ff05c0ac Mary Strodl 2024-10-09 313 c46a74ff05c0ac Mary Strodl 2024-10-09 314 for (offset = 0; offset < priv->gpio.ngpio; ++offset) c46a74ff05c0ac Mary Strodl 2024-10-09 315 old_value[offset] = -1; c46a74ff05c0ac Mary Strodl 2024-10-09 316 a14b0c5e3b0741 Mary Strodl 2025-09-23 317 /* a14b0c5e3b0741 Mary Strodl 2025-09-23 318 * We only want one worker. Workers race to acquire irq_race and tear a14b0c5e3b0741 Mary Strodl 2025-09-23 319 * down all other workers. This is a cond guard so that we don't deadlock a14b0c5e3b0741 Mary Strodl 2025-09-23 320 * trying to cancel a worker. a14b0c5e3b0741 Mary Strodl 2025-09-23 321 */ a14b0c5e3b0741 Mary Strodl 2025-09-23 322 scoped_cond_guard(mutex_try, ;, &priv->irq_race) { a14b0c5e3b0741 Mary Strodl 2025-09-23 323 scoped_guard(rcu) { a14b0c5e3b0741 Mary Strodl 2025-09-23 324 list_for_each_entry_rcu(worker, &priv->workers, list) { a14b0c5e3b0741 Mary Strodl 2025-09-23 325 /* Don't stop ourselves */ a14b0c5e3b0741 Mary Strodl 2025-09-23 326 if (worker == my_worker) a14b0c5e3b0741 Mary Strodl 2025-09-23 327 continue; a14b0c5e3b0741 Mary Strodl 2025-09-23 328 a14b0c5e3b0741 Mary Strodl 2025-09-23 329 scoped_guard(raw_spinlock_irqsave, &priv->irq_spin) a14b0c5e3b0741 Mary Strodl 2025-09-23 330 list_del_rcu(&worker->list); a14b0c5e3b0741 Mary Strodl 2025-09-23 331 a14b0c5e3b0741 Mary Strodl 2025-09-23 332 /* Give worker a chance to terminate itself */ a14b0c5e3b0741 Mary Strodl 2025-09-23 333 atomic_set(&worker->cancelled, 1); a14b0c5e3b0741 Mary Strodl 2025-09-23 334 /* Keep track of stuff to cancel */ a14b0c5e3b0741 Mary Strodl 2025-09-23 335 INIT_LIST_HEAD(&worker->destroy); a14b0c5e3b0741 Mary Strodl 2025-09-23 336 list_add(&worker->destroy, &destructors); a14b0c5e3b0741 Mary Strodl 2025-09-23 337 } a14b0c5e3b0741 Mary Strodl 2025-09-23 338 } a14b0c5e3b0741 Mary Strodl 2025-09-23 339 /* Make sure list consumers are finished before we tear down */ a14b0c5e3b0741 Mary Strodl 2025-09-23 340 synchronize_rcu(); a14b0c5e3b0741 Mary Strodl 2025-09-23 @341 list_for_each_entry(worker, &destructors, destroy) a14b0c5e3b0741 Mary Strodl 2025-09-23 @342 gpio_mpsse_stop(worker); This needs to be list_for_each_entry_save() because gpio_mpsse_stop() frees the worker. Or kfree_rcu() inside an rcu lock or something. a14b0c5e3b0741 Mary Strodl 2025-09-23 343 } a14b0c5e3b0741 Mary Strodl 2025-09-23 344 a14b0c5e3b0741 Mary Strodl 2025-09-23 345 while ((irq_enabled = atomic_read(&priv->irq_enabled)) && -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki