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Re: [libvirt] [PATCH v3 2/6] udev: Split udevEventHandleCallback in two functions



On Mon, Aug 28, 2017 at 11:04:35AM -0400, John Ferlan wrote:
>
>
> On 08/24/2017 07:23 AM, Erik Skultety wrote:
> > This patch splits udevEventHandleCallback in two (introduces
> > udevEventHandleThread) in order to be later able to refactor the latter
> > to actually become a detached thread which will wait some time for the
> > kernel to create the whole sysfs tree for a device as we cannot do that
> > in the event loop directly.
> >
> > Signed-off-by: Erik Skultety <eskultet redhat com>
> > ---
> >  src/node_device/node_device_udev.c | 54 ++++++++++++++++++++++++++------------
> >  1 file changed, 37 insertions(+), 17 deletions(-)
> >
> > diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
> > index 465d272ba..fe943c78b 100644
> > --- a/src/node_device/node_device_udev.c
> > +++ b/src/node_device/node_device_udev.c
> > @@ -1647,36 +1647,56 @@ udevCheckMonitorFD(struct udev_monitor *udev_monitor, int fd)
> >
> >
> >  static void
> > +udevEventHandleThread(void *opaque ATTRIBUTE_UNUSED)
>
> It's not ATTRIBUTE_UNUSED
>
> > +{
> > +    struct udev_device *device = NULL;
> > +    struct udev_monitor *udev_monitor = NULL;
> > +    int fd = (intptr_t) opaque;
>
> ^^^  opaque!

Right, good catch, thanks.

>
> > +
> > +    nodeDeviceLock();
> > +    udev_monitor = DRV_STATE_UDEV_MONITOR(driver);
> > +
> > +    if (!udevCheckMonitorFD(udev_monitor, fd))
> > +        goto unlock;
> > +
> > +    device = udev_monitor_receive_device(udev_monitor);
> > +    if (device == NULL) {
> > +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> > +                       _("udev_monitor_receive_device returned NULL"));
> > +        goto unlock;
> > +    }
> > +
> > +    nodeDeviceUnlock();
> > +    udevHandleOneDevice(device);
> > +
> > + cleanup:
> > +    udev_device_unref(device);
> > +    return;
> > +
> > + unlock:
> > +    nodeDeviceUnlock();
> > +    goto cleanup;
> > +}
> > +
> > +
> > +static void
> >  udevEventHandleCallback(int watch ATTRIBUTE_UNUSED,
> >                          int fd,
> >                          int events ATTRIBUTE_UNUSED,
> >                          void *data ATTRIBUTE_UNUSED)
> >  {
> > -    struct udev_device *device = NULL;
> >      struct udev_monitor *udev_monitor = NULL;
> >
> >      nodeDeviceLock();
> >      udev_monitor = DRV_STATE_UDEV_MONITOR(driver);
> >
> > -    if (!udevCheckMonitorFD(udev_monitor, fd))
> > -        goto unlock;
> > -
> > -    if (!(device = udev_monitor_receive_device(udev_monitor))) {
> > -        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> > -                       _("udev_monitor_receive_device returned NULL"));
> > -        goto unlock;
> > +    if (!udevCheckMonitorFD(udev_monitor, fd)) {
> > +        nodeDeviceUnlock();
> > +        return;
> >      }
>
> The above sequence will be done twice - once here and repeated again in
> HandleThread. I understand why, but as I get to patch 3 - I'm not sure
> things are going to work as expected.

Okay, let's continue with the discussion in patch 3 comments :).

Erik


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