From: Amos Kong Subject: [PATCH v5 REPOST 2/6] hw_random: move some code out mutex_lock for avoiding underlying deadlock Date: Mon, 8 Dec 2014 16:50:36 +0800 Message-ID: <1418028640-4891-3-git-send-email-akong@redhat.com> References: <1418028640-4891-1-git-send-email-akong@redhat.com> Cc: virtualization@lists.linux-foundation.org, herbert@gondor.apana.org.au, rusty@rustcorp.com.au, kvm@vger.kernel.org, m@bues.ch, mpm@selenic.com, amit.shah@redhat.com, linux-kernel@vger.kernel.org To: linux-crypto@vger.kernel.org Return-path: In-Reply-To: <1418028640-4891-1-git-send-email-akong@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.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