From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932153AbbAHMZx (ORCPT ); Thu, 8 Jan 2015 07:25:53 -0500 Received: from hqemgate16.nvidia.com ([216.228.121.65]:5227 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752893AbbAHMZv (ORCPT ); Thu, 8 Jan 2015 07:25:51 -0500 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Thu, 08 Jan 2015 04:24:22 -0800 From: Jim Lin To: linus.walleij@linaro.org CC: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Jim Lin Subject: [PATCH 1/1] pinctrl: Fix two deadlocks Date: Thu, 8 Jan 2015 20:25:05 +0800 Message-ID: <1420719905-15994-1-git-send-email-jilin@nvidia.com> X-Mailer: git-send-email 1.7.7 X-NVConfidentiality: public MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch is to fix two deadlock cases. Deadlock 1: CPU #1 pinctrl_register-> pinctrl_get -> create_pinctrl (Holding lock pinctrl_maps_mutex) -> get_pinctrl_dev_from_devname (Trying to acquire lock pinctrldev_list_mutex) CPU #0 pinctrl_unregister (Holding lock pinctrldev_list_mutex) -> pinctrl_put ->> pinctrl_free -> pinctrl_dt_free_maps -> pinctrl_unregister_map (Trying to acquire lock pinctrl_maps_mutex) Simply to say CPU#1 is holding lock A and trying to acquire lock B, CPU#0 is holding lock B and trying to acquire lock A. Deadlock 2: CPU #3 pinctrl_register-> pinctrl_get -> create_pinctrl (Holding lock pinctrl_maps_mutex) -> get_pinctrl_dev_from_devname (Trying to acquire lock pinctrldev_list_mutex) CPU #2 pinctrl_unregister (Holding lock pctldev->mutex) -> pinctrl_put ->> pinctrl_free -> pinctrl_dt_free_maps -> pinctrl_unregister_map (Trying to acquire lock pinctrl_maps_mutex) CPU #0 tegra_gpio_request (Holding lock pinctrldev_list_mutex) -> pinctrl_get_device_gpio_range (Trying to acquire lock pctldev->mutex) Simply to say CPU#3 is holding lock A and trying to acquire lock D, CPU#2 is holding lock B and trying to acquire lock A, CPU#0 is holding lock D and trying to acquire lock B. Signed-off-by: Jim Lin --- drivers/pinctrl/core.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c index e4f65510c87e..89dca77ca038 100644 --- a/drivers/pinctrl/core.c +++ b/drivers/pinctrl/core.c @@ -1801,14 +1801,15 @@ void pinctrl_unregister(struct pinctrl_dev *pctldev) if (pctldev == NULL) return; - mutex_lock(&pinctrldev_list_mutex); mutex_lock(&pctldev->mutex); - pinctrl_remove_device_debugfs(pctldev); + mutex_unlock(&pctldev->mutex); if (!IS_ERR(pctldev->p)) pinctrl_put(pctldev->p); + mutex_lock(&pinctrldev_list_mutex); + mutex_lock(&pctldev->mutex); /* TODO: check that no pinmuxes are still active? */ list_del(&pctldev->node); /* Destroy descriptor tree */ -- 1.7.7