From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755883AbaIRMjS (ORCPT ); Thu, 18 Sep 2014 08:39:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49501 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755449AbaIRMiU (ORCPT ); Thu, 18 Sep 2014 08:38:20 -0400 From: Amos Kong To: virtualization@lists.linux-foundation.org Cc: kvm@vger.kernel.org, herbert@gondor.apana.org.au, m@bues.ch, mpm@selenic.com, amit.shah@redhat.com, rusty@rustcorp.com.au, linux-kernel@vger.kernel.org Subject: [PATCH v2 4/6] hw_random: fix unregister race. Date: Thu, 18 Sep 2014 20:37:45 +0800 Message-Id: <1411043867-21109-5-git-send-email-akong@redhat.com> In-Reply-To: <1411043867-21109-1-git-send-email-akong@redhat.com> References: <1411043867-21109-1-git-send-email-akong@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rusty Russell The previous patch added one potential problem: we can still be reading from a hwrng when it's unregistered. Add a wait for zero in the hwrng_unregister path. Signed-off-by: Rusty Russell --- drivers/char/hw_random/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c index ee9e504..9f6f5bb 100644 --- a/drivers/char/hw_random/core.c +++ b/drivers/char/hw_random/core.c @@ -60,6 +60,7 @@ static DEFINE_MUTEX(rng_mutex); static DEFINE_MUTEX(reading_mutex); static int data_avail; static u8 *rng_buffer, *rng_fillbuf; +static DECLARE_WAIT_QUEUE_HEAD(rng_done); static unsigned short current_quality; static unsigned short default_quality; /* = 0; default to "off" */ @@ -98,6 +99,7 @@ static inline void cleanup_rng(struct kref *kref) if (rng->cleanup) rng->cleanup(rng); + wake_up_all(&rng_done); } static void set_current_rng(struct hwrng *rng) -- 1.9.3