From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752066AbdILQ5P (ORCPT ); Tue, 12 Sep 2017 12:57:15 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48366 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751719AbdILQ5I (ORCPT ); Tue, 12 Sep 2017 12:57:08 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Archit Taneja , Thong Ho , Nhan Nguyen Subject: [PATCH 4.4 22/31] drm/bridge: adv7511: Fix mutex deadlock when interrupts are disabled Date: Tue, 12 Sep 2017 09:56:17 -0700 Message-Id: <20170912165248.480542824@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170912165247.436880944@linuxfoundation.org> References: <20170912165247.436880944@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Archit Taneja commit f0bfcc22d9822947b0ad3095e8363eab5261864c upstream. When the adv7511 i2c client doesn't have an interrupt line, we observe a deadlock on caused by trying to lock drm device's mode_config.mutex twice in the same context. Here is the sequence that causes it: ioctl DRM_IOCTL_MODE_GETCONNECTOR from userspace drm_mode_getconnector (acquires mode_config mutex) connector->fill_modes() drm_helper_probe_single_connector_modes connector_funcs->get_modes adv7511_encoder_get_modes adv7511_get_edid_block adv7511_irq_process drm_helper_hpd_irq_event (acquires mode_config mutex again) In adv7511_irq_process, don't call drm_helper_hpd_irq_event when not called from the interrupt handler. It doesn't serve any purpose there anyway. Signed-off-by: Archit Taneja Signed-off-by: Thong Ho Signed-off-by: Nhan Nguyen Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i2c/adv7511.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/drivers/gpu/drm/i2c/adv7511.c +++ b/drivers/gpu/drm/i2c/adv7511.c @@ -429,7 +429,7 @@ static bool adv7511_hpd(struct adv7511 * return false; } -static int adv7511_irq_process(struct adv7511 *adv7511) +static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd) { unsigned int irq0, irq1; int ret; @@ -445,7 +445,7 @@ static int adv7511_irq_process(struct ad regmap_write(adv7511->regmap, ADV7511_REG_INT(0), irq0); regmap_write(adv7511->regmap, ADV7511_REG_INT(1), irq1); - if (irq0 & ADV7511_INT0_HDP && adv7511->encoder) + if (process_hpd && irq0 & ADV7511_INT0_HDP && adv7511->encoder) drm_helper_hpd_irq_event(adv7511->encoder->dev); if (irq0 & ADV7511_INT0_EDID_READY || irq1 & ADV7511_INT1_DDC_ERROR) { @@ -463,7 +463,7 @@ static irqreturn_t adv7511_irq_handler(i struct adv7511 *adv7511 = devid; int ret; - ret = adv7511_irq_process(adv7511); + ret = adv7511_irq_process(adv7511, true); return ret < 0 ? IRQ_NONE : IRQ_HANDLED; } @@ -480,7 +480,7 @@ static int adv7511_wait_for_edid(struct adv7511->edid_read, msecs_to_jiffies(timeout)); } else { for (; timeout > 0; timeout -= 25) { - ret = adv7511_irq_process(adv7511); + ret = adv7511_irq_process(adv7511, false); if (ret < 0) break;