[Qemu-devel] Re: [PATCH V6 18/32] pci: remove bus_num member from struct PCIBus.

[Isaku Yamahata]

On Tue, Nov 10, 2009 at 05:46:40PM +0200, Michael S. Tsirkin wrote:
> On Tue, Nov 10, 2009 at 05:33:22PM +0200, Michael S. Tsirkin wrote:
> > On Fri, Oct 30, 2009 at 09:21:12PM +0900, Isaku Yamahata wrote:
> > > Since It can be retrieved from pci configuration space,
> > > the member is unnecessary.
> > > 
> > > Signed-off-by: Isaku Yamahata <address@hidden>
> > 
> > Acked-by: Michael S. Tsirkin <address@hidden>
> 
> Sorry, wait a second please:
> 
> > > ---
> > >  hw/pci.c |   21 ++++++++++-----------
> > >  1 files changed, 10 insertions(+), 11 deletions(-)
> > > 
> > > diff --git a/hw/pci.c b/hw/pci.c
> > > index 7da3db9..a75d981 100644
> > > --- a/hw/pci.c
> > > +++ b/hw/pci.c
> > > @@ -36,7 +36,6 @@
> > >  
> > >  struct PCIBus {
> > >      BusState qbus;
> > > -    int bus_num;
> > >      int devfn_min;
> > >      pci_set_irq_fn set_irq;
> > >      pci_map_irq_fn map_irq;
> > > @@ -192,7 +191,9 @@ static void pci_register_secondary_bus(PCIBus *bus,
> > >  
> > >  int pci_bus_num(PCIBus *s)
> > >  {
> > > -    return s->bus_num;
> > > +    if (!s->parent_dev)
> > > +        return 0;       /* pci host bridge */
> > > +    return s->parent_dev->config[PCI_SECONDARY_BUS];
> 
> Why are you using the value from the *parent*?
> Because originally ...

You seem to be confuging PCIBus with PCIBridge.
"s" here is PCIBus. "s" in pci_brdige_write_config() is PCIBrdige.
And both PCIBridge and PCIDevice have bus member,
so it's more confusing.

              NULL
               ^
               | PCIBus::parent_dev
               |
            PCIBus (pci host bridge)
                includes
                devices[256]
               ^
               | PCIDevice::bus
               |
            PCIBridge
               includes PCIDevice
              | ^
PCIBridge::bus| | PCIBus::parent_dev
              v |
            PCIBus


thanks,

 > >  }
> > >  
> > >  static int get_pci_config_device(QEMUFile *f, void *pv, size_t size)
> > > @@ -624,7 +625,7 @@ void pci_data_write(void *opaque, uint32_t addr, 
> > > uint32_t val, int len)
> > >                  addr, val, len);
> > >  #endif
> > >      bus_num = (addr >> 16) & 0xff;
> > > -    while (s && s->bus_num != bus_num)
> > > +    while (s && pci_bus_num(s) != bus_num)
> > >          s = s->next;
> > >      if (!s)
> > >          return;
> > > @@ -645,7 +646,7 @@ uint32_t pci_data_read(void *opaque, uint32_t addr, 
> > > int len)
> > >      uint32_t val;
> > >  
> > >      bus_num = (addr >> 16) & 0xff;
> > > -    while (s && s->bus_num != bus_num)
> > > +    while (s && pci_bus_num(s) != bus_num)
> > >          s= s->next;
> > >      if (!s)
> > >          goto fail;
> > > @@ -760,7 +761,8 @@ static void pci_info_device(PCIDevice *d)
> > >      const pci_class_desc *desc;
> > >  
> > >      monitor_printf(mon, "  Bus %2d, device %3d, function %d:\n",
> > > -                   d->bus->bus_num, PCI_SLOT(d->devfn), 
> > > PCI_FUNC(d->devfn));
> > > +                   pci_bus_num(d->bus),
> > > +                   PCI_SLOT(d->devfn), PCI_FUNC(d->devfn));
> > >      class = pci_get_word(d->config + PCI_CLASS_DEVICE);
> > >      monitor_printf(mon, "    ");
> > >      desc = pci_class_descriptions;
> > > @@ -816,7 +818,7 @@ void pci_for_each_device(int bus_num, void 
> > > (*fn)(PCIDevice *d))
> > >      PCIDevice *d;
> > >      int devfn;
> > >  
> > > -    while (bus && bus->bus_num != bus_num)
> > > +    while (bus && pci_bus_num(bus) != bus_num)
> > >          bus = bus->next;
> > >      if (bus) {
> > >          for(devfn = 0; devfn < 256; devfn++) {
> > > @@ -913,17 +915,14 @@ typedef struct {
> > >  static void pci_bridge_write_config(PCIDevice *d,
> > >                               uint32_t address, uint32_t val, int len)
> > >  {
> > > -    PCIBridge *s = (PCIBridge *)d;
> > > -
> > >      pci_default_write_config(d, address, val, len);
> > > -    s->bus.bus_num = d->config[PCI_SECONDARY_BUS];
> 
> ... bus number used to equal PCI_SECONDARY_BUS for the *same* device.
> 
> > >  }
> > >  
> > >  PCIBus *pci_find_bus(int bus_num)
> > >  {
> > >      PCIBus *bus = first_bus;
> > >  
> > > -    while (bus && bus->bus_num != bus_num)
> > > +    while (bus && pci_bus_num(bus) != bus_num)
> > >          bus = bus->next;
> > >  
> > >      return bus;
> > > @@ -1149,7 +1148,7 @@ static void pcibus_dev_print(Monitor *mon, 
> > > DeviceState *dev, int indent)
> > >      monitor_printf(mon, "%*sclass %s, addr %02x:%02x.%x, "
> > >                     "pci id %04x:%04x (sub %04x:%04x)\n",
> > >                     indent, "", ctxt,
> > > -                   d->bus->bus_num, PCI_SLOT(d->devfn), 
> > > PCI_FUNC(d->devfn),
> > > +                   pci_bus_num(d->bus), PCI_SLOT(d->devfn), 
> > > PCI_FUNC(d->devfn),
> > >                     pci_get_word(d->config + PCI_VENDOR_ID),
> > >                     pci_get_word(d->config + PCI_DEVICE_ID),
> > >                     pci_get_word(d->config + PCI_SUBSYSTEM_VENDOR_ID),
> 

-- 
yamahata