From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amos Kong 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> References: <1411043867-21109-1-git-send-email-akong@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1411043867-21109-1-git-send-email-akong@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: virtualization@lists.linux-foundation.org Cc: herbert@gondor.apana.org.au, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, m@bues.ch, mpm@selenic.com, amit.shah@redhat.com List-Id: virtualization@lists.linuxfoundation.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