* [bug report] PCI: Protect pci_reassign_bridge_resources() against addition/removal
@ 2019-09-04 10:03 Dan Carpenter
2019-09-09 8:13 ` Benjamin Herrenschmidt
0 siblings, 1 reply; 3+ messages in thread
From: Dan Carpenter @ 2019-09-04 10:03 UTC (permalink / raw)
To: benh; +Cc: linux-pci
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'.
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [bug report] PCI: Protect pci_reassign_bridge_resources() against addition/removal
2019-09-04 10:03 [bug report] PCI: Protect pci_reassign_bridge_resources() against addition/removal Dan Carpenter
@ 2019-09-09 8:13 ` Benjamin Herrenschmidt
2019-09-23 21:50 ` Bjorn Helgaas
0 siblings, 1 reply; 3+ messages in thread
From: Benjamin Herrenschmidt @ 2019-09-09 8:13 UTC (permalink / raw)
To: Dan Carpenter; +Cc: linux-pci
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [bug report] PCI: Protect pci_reassign_bridge_resources() against addition/removal
2019-09-09 8:13 ` Benjamin Herrenschmidt
@ 2019-09-23 21:50 ` Bjorn Helgaas
0 siblings, 0 replies; 3+ messages in thread
From: Bjorn Helgaas @ 2019-09-23 21:50 UTC (permalink / raw)
To: Benjamin Herrenschmidt; +Cc: Dan Carpenter, linux-pci
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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-09-23 21:50 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2019-09-04 10:03 [bug report] PCI: Protect pci_reassign_bridge_resources() against addition/removal Dan Carpenter
2019-09-09 8:13 ` Benjamin Herrenschmidt
2019-09-23 21:50 ` Bjorn Helgaas
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