On Mon, Sep 09, 2019 at 09:13:28AM +0100, Benjamin Herrenschmidt wrote:
> On Wed, 2019-09-04 at 13:03 +0300, Dan Carpenter wrote:
> > Hello Benjamin Herrenschmidt,
> >
> > The patch 540f62d26f02: "PCI: Protect pci_reassign_bridge_resources()
> > against addition/removal" from Jun 24, 2019, leads to the following
> > static checker warning:
> >
> > drivers/pci/setup-bus.c:2158 pci_reassign_bridge_resources()
> > warn: inconsistent returns 'read_sem:&pci_bus_sem'.
>
> Thanks, I missed that. I'll try to send something but from Plumbers
> might be difficult...
I dropped this for now.
> > drivers/pci/setup-bus.c
> > 2066 unsigned int i;
> > 2067 int ret;
> > 2068
> > 2069 down_read(&pci_bus_sem);
> >
> > We added some new locking here.
> >
> > 2070
> > 2071 /* Walk to the root hub, releasing bridge BARs when
> > possible */
> > 2072 next = bridge;
> > 2073 do {
> > 2074 bridge = next;
> > 2075 for (i = PCI_BRIDGE_RESOURCES; i <
> > PCI_BRIDGE_RESOURCE_END;
> > 2076 i++) {
> > 2077 struct resource *res = &bridge-
> > >resource[i];
> > 2078
> > 2079 if ((res->flags ^ type) &
> > PCI_RES_TYPE_MASK)
> > 2080 continue;
> > 2081
> > 2082 /* Ignore BARs which are still in use
> > */
> > 2083 if (res->child)
> > 2084 continue;
> > 2085
> > 2086 ret = add_to_list(&saved, bridge,
> > res, 0, 0);
> > 2087 if (ret)
> > 2088 goto cleanup;
> > 2089
> > 2090 pci_info(bridge, "BAR %d: releasing
> > %pR\n",
> > 2091 i, res);
> > 2092
> > 2093 if (res->parent)
> > 2094 release_resource(res);
> > 2095 res->start = 0;
> > 2096 res->end = 0;
> > 2097 break;
> > 2098 }
> > 2099 if (i == PCI_BRIDGE_RESOURCE_END)
> > 2100 break;
> > 2101
> > 2102 next = bridge->bus ? bridge->bus->self :
> > NULL;
> > 2103 } while (next);
> > 2104
> > 2105 if (list_empty(&saved))
> > 2106 return -ENOENT;
> >
> > This needs an unlock. It's not clear to me if any other clean up is
> > required, but possibly it's worth looking at.
> >
> > 2107
> > 2108 __pci_bus_size_bridges(bridge->subordinate, &added);
> > 2109 __pci_bridge_assign_resources(bridge, &added,
> > &failed);
> >
> > regards,
> > dan carpenter
>
