From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amos Kong Subject: [PATCH v2 0/6] fix hw_random stuck Date: Thu, 18 Sep 2014 20:37:41 +0800 Message-ID: <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: 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 When I hotunplug a busy virtio-rng device or try to access hwrng attributes in non-smp guest, it gets stuck. My original was pain, Rusty posted a real fix. This patchset fixed two issue in v1, and tested by my 6+ cases. | test 0: | hotunplug rng device from qemu monitor | | test 1: | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 2: | guest) # dd if=/dev/random of=/dev/null & | hotunplug rng device from qemu monitor | | test 4: | guest) # dd if=/dev/hwrng of=/dev/null & | cat /sys/devices/virtual/misc/hw_random/rng_* | | test 5: | guest) # dd if=/dev/hwrng of=/dev/null | cancel dd process after 10 seconds | guest) # dd if=/dev/hwrng of=/dev/null & | hotunplug rng device from qemu monitor | | test 6: | use a fifo as rng backend, execute test 0 ~ 5 with no input of fifo V2: added patch 2 to fix a deadlock, update current patch 3 to fix reference counting issue Amos Kong (1): hw_random: move some code out mutex_lock for avoiding underlying deadlock Rusty Russell (5): hw_random: place mutex around read functions and buffers. hw_random: use reference counts on each struct hwrng. hw_random: fix unregister race. hw_random: don't double-check old_rng. hw_random: don't init list element we're about to add to list. drivers/char/hw_random/core.c | 166 +++++++++++++++++++++++++++++------------- include/linux/hw_random.h | 2 + 2 files changed, 117 insertions(+), 51 deletions(-) -- 1.9.3