From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754589AbbBSAod (ORCPT ); Wed, 18 Feb 2015 19:44:33 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:35670 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754060AbbBSAea (ORCPT ); Wed, 18 Feb 2015 19:34:30 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Jim Lin , Linus Walleij , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 075/103] pinctrl: Fix two deadlocks Date: Wed, 18 Feb 2015 16:32:42 -0800 Message-Id: <1424305990-17983-76-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1424305990-17983-1-git-send-email-kamal@canonical.com> References: <1424305990-17983-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11-ckt16 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Jim Lin commit db93facfb0ef542aa5d8079e47580b3e669a4d82 upstream. 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 Signed-off-by: Linus Walleij Signed-off-by: Kamal Mostafa --- drivers/pinctrl/core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c index cab020a..cceb863 100644 --- a/drivers/pinctrl/core.c +++ b/drivers/pinctrl/core.c @@ -1810,14 +1810,15 @@ 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 */ -- 1.9.1