Re: [Qemu-devel] [PATCH] qdev-monitor: Avoid exiting when hot-plugging two devices with the same bootindex value

[Marcel Apfelbaum]

On Thu, 2013-09-12 at 09:49 +0200, Paolo Bonzini wrote:
> Il 11/09/2013 20:26, Marcel Apfelbaum ha scritto:
> > Qemu is expected to quit if the same boot index value is used by two 
> > devices.
> > However, hot-plugging a device with a bootindex value already used should
> > fail with a friendly message rather than quitting a running VM.
> 
> I think the problem is right where QEMU exits, i.e. in
> add_boot_device_path.  This function should return an error instead, via
> an Error ** argument.
> 
> Callers, typically a device's init or realize function, will either
> print the error before returning an error code (e.g. -EBUSY for init) or
> propagate the error up (for realize).
Thanks, I'll try this.
Marcel

> Returning/propagating failure will still cause QEMU to exit when the
> duplicate bootindexes are found on the command line.
> 
> Paolo
> 
> > Signed-off-by: Marcel Apfelbaum <address@hidden>
> > ---
> >  qdev-monitor.c | 33 +++++++++++++++++++++++++++++++++
> >  1 file changed, 33 insertions(+)
> > 
> > diff --git a/qdev-monitor.c b/qdev-monitor.c
> > index 410cdcb..654d086 100644
> > --- a/qdev-monitor.c
> > +++ b/qdev-monitor.c
> > @@ -24,6 +24,7 @@
> >  #include "qmp-commands.h"
> >  #include "sysemu/arch_init.h"
> >  #include "qemu/config-file.h"
> > +#include "sysemu/sysemu.h"
> >  
> >  /*
> >   * Aliases were a bad idea from the start.  Let's keep them
> > @@ -442,6 +443,31 @@ static BusState *qbus_find(const char *path)
> >      }
> >  }
> >  
> > +#define OBJ_PROP_BOOTINDEX "bootindex"
> > +
> > +static bool bootindex_colision(Object *obj, QemuOpts *opts)
> > +{
> > +    int32_t bootindex;
> > +
> > +    if (!object_property_find(obj, OBJ_PROP_BOOTINDEX, NULL)) {
> > +        return false;
> > +    }
> > +
> > +    /* avoid parsing by setting the property and then getting it typed */
> > +    object_property_parse(obj, qemu_opt_get(opts, OBJ_PROP_BOOTINDEX),
> > +                          OBJ_PROP_BOOTINDEX, NULL);
> > +    bootindex = (int32_t)object_property_get_int(obj, OBJ_PROP_BOOTINDEX,
> > +                                                 NULL);
> > +
> > +    if (bootindex >= 0) {
> > +        if (get_boot_device(bootindex)) {
> > +            return true;
> > +        }
> > +    }
> > +
> > +    return false;
> > +}
> > +
> >  DeviceState *qdev_device_add(QemuOpts *opts)
> >  {
> >      ObjectClass *obj;
> > @@ -502,6 +528,13 @@ DeviceState *qdev_device_add(QemuOpts *opts)
> >      /* create device, set properties */
> >      qdev = DEVICE(object_new(driver));
> >  
> > +    if (qdev_hotplug && bootindex_colision(OBJECT(qdev), opts)) {
> > +        qerror_report(QERR_INVALID_PARAMETER_VALUE,
> > +                      "bootindex", "an unused boot index value");
> > +        qdev_free(qdev);
> > +        return NULL;
> > +    }
> > +
> >      if (bus) {
> >          qdev_set_parent_bus(qdev, bus);
> >      }
> > 
>