From db7d4d7f40215843000cb9d441c9149fd42ea36b Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Fri, 1 May 2015 16:31:41 -0600 Subject: [PATCH] vfio: Fix runaway interruptible timeout Commit 13060b64b819 ("vfio: Add and use device request op for vfio bus drivers") incorrectly makes use of an interruptible timeout. When interrupted, the signal remains pending resulting in subsequent timeouts occurring instantly. This makes the loop spin at a much higher rate than intended. Instead of making this completely non-interruptible, we can change this into a sort of interruptible-once behavior and use the "once" to log debug information. The driver API doesn't allow us to abort and return an error code. Signed-off-by: Alex Williamson Fixes: 13060b64b819 Cc: stable@vger.kernel.org # v4.0 --- drivers/vfio/vfio.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 0d336625ac71..e1278fe04b1e 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -710,6 +710,8 @@ void *vfio_del_group_dev(struct device *dev) void *device_data = device->device_data; struct vfio_unbound_dev *unbound; unsigned int i = 0; + long ret; + bool interrupted = false; /* * The group exists so long as we have a device reference. Get @@ -755,9 +757,22 @@ void *vfio_del_group_dev(struct device *dev) vfio_device_put(device); - } while (wait_event_interruptible_timeout(vfio.release_q, - !vfio_dev_present(group, dev), - HZ * 10) <= 0); + if (interrupted) { + ret = wait_event_timeout(vfio.release_q, + !vfio_dev_present(group, dev), HZ * 10); + } else { + ret = wait_event_interruptible_timeout(vfio.release_q, + !vfio_dev_present(group, dev), HZ * 10); + if (ret == -ERESTARTSYS) { + interrupted = true; + dev_warn(dev, + "Device is currently in use, task" + " \"%s\" (%d) " + "blocked until device is released", + current->comm, task_pid_nr(current)); + } + } + } while (ret <= 0); vfio_group_put(group);