Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752835AbaKCP56 (ORCPT ); Mon, 3 Nov 2014 10:57:58 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60818 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752895AbaKCP5x (ORCPT ); Mon, 3 Nov 2014 10:57:53 -0500 From: Amos Kong To: virtualization@lists.linux-foundation.org Cc: kvm@vger.kernel.org, rusty@rustcorp.com.au, herbert@gondor.apana.org.au, m@bues.ch, mb@bu3sch.de, mpm@selenic.com, amit.shah@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH v4 2/6] hw_random: move some code out mutex_lock for avoiding underlying deadlock Date: Mon, 3 Nov 2014 23:56:22 +0800 Message-Id: <1415030186-18303-3-git-send-email-akong@redhat.com> In-Reply-To: <1415030186-18303-1-git-send-email-akong@redhat.com> References: <1415030186-18303-1-git-send-email-akong@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In next patch, we use reference counting for each struct hwrng, changing reference count also needs to take mutex_lock. Before releasing the lock, if we try to stop a kthread that waits to take the lock to reduce the referencing count, deadlock will occur. Signed-off-by: Amos Kong --- drivers/char/hw_random/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index b1b6042..a0905c8 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -474,12 +474,12 @@ void hwrng_unregister(struct hwrng *rng) } } if (list_empty(&rng_list)) { + mutex_unlock(&rng_mutex); unregister_miscdev(); if (hwrng_fill) kthread_stop(hwrng_fill); - } - - mutex_unlock(&rng_mutex); + } else + mutex_unlock(&rng_mutex); } EXPORT_SYMBOL_GPL(hwrng_unregister); -- 1.9.3 -- 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/