Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752650AbbFNOzS (ORCPT ); Sun, 14 Jun 2015 10:55:18 -0400 Received: from opensource.wolfsonmicro.com ([80.75.67.52]:45393 "EHLO opensource.wolfsonmicro.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751417AbbFNOzM (ORCPT ); Sun, 14 Jun 2015 10:55:12 -0400 From: Charles Keepax To: lee.jones@linaro.org Cc: sameo@linux.intel.com, patches@opensource.wolfsonmicro.com, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] mfd: arizona: Fix race between runtime suspend and IRQs Date: Sun, 14 Jun 2015 15:41:49 +0100 Message-Id: <1434292910-24919-1-git-send-email-ckeepax@opensource.wolfsonmicro.com> X-Mailer: git-send-email 1.7.2.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1916 Lines: 44 The function arizona_irq_thread (the threaded handler for the arizona IRQs) calls pm_runtime_get_sync at the start to ensure that the chip is active as we handle the IRQ. If the chip is part way through a runtime suspend when an IRQ arrives the PM core will wait for the suspend to complete, before resuming. However, since commit 4f0216409f7c ("mfd: arizona: Add better support for system suspend") the runtime suspend function may call disable_irq, if the chip is going to fully power off, which will try to wait for any outstanding IRQs to complete. This results in deadlock as the IRQ thread is waiting for the PM operation to complete and the PM thread is waiting for the IRQ to complete. To avoid this situation we use disable_irq_nosync, which allows the suspending thread to finish the suspend without waiting for the IRQ to complete. This is safe because if an IRQ is being processed it can only be blocked at the pm_runtime_get_sync at the start of the handler otherwise it wouldn't be possible to suspend. Signed-off-by: Charles Keepax --- drivers/mfd/arizona-core.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/mfd/arizona-core.c b/drivers/mfd/arizona-core.c index bebf58a..e60bcd9 100644 --- a/drivers/mfd/arizona-core.c +++ b/drivers/mfd/arizona-core.c @@ -651,7 +651,7 @@ static int arizona_runtime_suspend(struct device *dev) arizona->has_fully_powered_off = true; - disable_irq(arizona->irq); + disable_irq_nosync(arizona->irq); arizona_enable_reset(arizona); regulator_bulk_disable(arizona->num_core_supplies, arizona->core_supplies); -- 1.7.2.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/