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...
Cheers
Ben.
> 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
