[PATCH-for-5.2 v2] hw/i386/acpi-build: Fix maybe-uninitialized error when ACPI hotplug off

[PATCH-for-5.2 v2] hw/i386/acpi-build: Fix maybe-uninitialized error when ACPI hotplug off

[Philippe Mathieu-Daudé]

GCC 9.3.0 thinks that 'method' can be left uninitialized. This code
is already in the "if (bsel || pcihp_bridge_en)" block statement,
but it isn't smart enough to figure it out.

Restrict the code to be used only in the "if (bsel || pcihp_bridge_en)"
block statement to fix (on Ubuntu):

  ../hw/i386/acpi-build.c: In function 'build_append_pci_bus_devices':
  ../hw/i386/acpi-build.c:496:9: error: 'method' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]
    496 |         aml_append(parent_scope, method);
        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors

Fixes: df4008c9c59 ("piix4: don't reserve hw resources when hotplug is off globally")
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/i386/acpi-build.c | 45 +++++++++++++++++++++-----------------------
 1 file changed, 21 insertions(+), 24 deletions(-)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 4f66642d887..1f5c2112452 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -465,34 +465,31 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
      */
     if (bsel || pcihp_bridge_en) {
         method = aml_method("PCNT", 0, AML_NOTSERIALIZED);
-    }
-    /* If bus supports hotplug select it and notify about local events */
-    if (bsel) {
-        uint64_t bsel_val = qnum_get_uint(qobject_to(QNum, bsel));
 
-        aml_append(method, aml_store(aml_int(bsel_val), aml_name("BNUM")));
-        aml_append(method,
-            aml_call2("DVNT", aml_name("PCIU"), aml_int(1) /* Device Check */)
-        );
-        aml_append(method,
-            aml_call2("DVNT", aml_name("PCID"), aml_int(3)/* Eject Request */)
-        );
-    }
+        /* If bus supports hotplug select it and notify about local events */
+        if (bsel) {
+            uint64_t bsel_val = qnum_get_uint(qobject_to(QNum, bsel));
 
-    /* Notify about child bus events in any case */
-    if (pcihp_bridge_en) {
-        QLIST_FOREACH(sec, &bus->child, sibling) {
-            int32_t devfn = sec->parent_dev->devfn;
-
-            if (pci_bus_is_root(sec) || pci_bus_is_express(sec)) {
-                continue;
-            }
-
-            aml_append(method, aml_name("^S%.02X.PCNT", devfn));
+            aml_append(method, aml_store(aml_int(bsel_val), aml_name("BNUM")));
+            aml_append(method, aml_call2("DVNT", aml_name("PCIU"),
+                                         aml_int(1))); /* Device Check */
+            aml_append(method, aml_call2("DVNT", aml_name("PCID"),
+                                         aml_int(3))); /* Eject Request */
+        }
+
+        /* Notify about child bus events in any case */
+        if (pcihp_bridge_en) {
+            QLIST_FOREACH(sec, &bus->child, sibling) {
+                int32_t devfn = sec->parent_dev->devfn;
+
+                if (pci_bus_is_root(sec) || pci_bus_is_express(sec)) {
+                    continue;
+                }
+
+                aml_append(method, aml_name("^S%.02X.PCNT", devfn));
+            }
         }
-    }
 
-    if (bsel || pcihp_bridge_en) {
         aml_append(parent_scope, method);
     }
     qobject_unref(bsel);
-- 
2.26.2

Re: [PATCH-for-5.2 v2] hw/i386/acpi-build: Fix maybe-uninitialized error when ACPI hotplug off

[Ani Sinha]

On Sun, Nov 8, 2020 at 1:10 AM Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
>
> GCC 9.3.0 thinks that 'method' can be left uninitialized. This code
> is already in the "if (bsel || pcihp_bridge_en)" block statement,
> but it isn't smart enough to figure it out.
>
> Restrict the code to be used only in the "if (bsel || pcihp_bridge_en)"
> block statement to fix (on Ubuntu):
>
>   ../hw/i386/acpi-build.c: In function 'build_append_pci_bus_devices':
>   ../hw/i386/acpi-build.c:496:9: error: 'method' may be used uninitialized
>   in this function [-Werror=maybe-uninitialized]
>     496 |         aml_append(parent_scope, method);
>         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   cc1: all warnings being treated as errors

OK I looked at the patch closely and it makes sense. Can you please
run a "make check" to make sure we have not broken anything?

>
> Fixes: df4008c9c59 ("piix4: don't reserve hw resources when hotplug is off globally")
Acked-by: Ani Sinha <ani@anisinha.ca>

> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  hw/i386/acpi-build.c | 45 +++++++++++++++++++++-----------------------
>  1 file changed, 21 insertions(+), 24 deletions(-)
>
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 4f66642d887..1f5c2112452 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -465,34 +465,31 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
>       */
>      if (bsel || pcihp_bridge_en) {
>          method = aml_method("PCNT", 0, AML_NOTSERIALIZED);
> -    }
> -    /* If bus supports hotplug select it and notify about local events */
> -    if (bsel) {
> -        uint64_t bsel_val = qnum_get_uint(qobject_to(QNum, bsel));
>
> -        aml_append(method, aml_store(aml_int(bsel_val), aml_name("BNUM")));
> -        aml_append(method,
> -            aml_call2("DVNT", aml_name("PCIU"), aml_int(1) /* Device Check */)
> -        );
> -        aml_append(method,
> -            aml_call2("DVNT", aml_name("PCID"), aml_int(3)/* Eject Request */)
> -        );
> -    }
> +        /* If bus supports hotplug select it and notify about local events */
> +        if (bsel) {
> +            uint64_t bsel_val = qnum_get_uint(qobject_to(QNum, bsel));
>
> -    /* Notify about child bus events in any case */
> -    if (pcihp_bridge_en) {
> -        QLIST_FOREACH(sec, &bus->child, sibling) {
> -            int32_t devfn = sec->parent_dev->devfn;
> -
> -            if (pci_bus_is_root(sec) || pci_bus_is_express(sec)) {
> -                continue;
> -            }
> -
> -            aml_append(method, aml_name("^S%.02X.PCNT", devfn));
> +            aml_append(method, aml_store(aml_int(bsel_val), aml_name("BNUM")));
> +            aml_append(method, aml_call2("DVNT", aml_name("PCIU"),
> +                                         aml_int(1))); /* Device Check */
> +            aml_append(method, aml_call2("DVNT", aml_name("PCID"),
> +                                         aml_int(3))); /* Eject Request */
> +        }
> +
> +        /* Notify about child bus events in any case */
> +        if (pcihp_bridge_en) {
> +            QLIST_FOREACH(sec, &bus->child, sibling) {
> +                int32_t devfn = sec->parent_dev->devfn;
> +
> +                if (pci_bus_is_root(sec) || pci_bus_is_express(sec)) {
> +                    continue;
> +                }
> +
> +                aml_append(method, aml_name("^S%.02X.PCNT", devfn));
> +            }
>          }
> -    }
>
> -    if (bsel || pcihp_bridge_en) {
>          aml_append(parent_scope, method);
>      }
>      qobject_unref(bsel);
> --
> 2.26.2
>

Re: [PATCH-for-5.2 v2] hw/i386/acpi-build: Fix maybe-uninitialized error when ACPI hotplug off

[Philippe Mathieu-Daudé]

On 11/8/20 4:58 AM, Ani Sinha wrote:
> On Sun, Nov 8, 2020 at 1:10 AM Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
>>
>> GCC 9.3.0 thinks that 'method' can be left uninitialized. This code
>> is already in the "if (bsel || pcihp_bridge_en)" block statement,
>> but it isn't smart enough to figure it out.
>>
>> Restrict the code to be used only in the "if (bsel || pcihp_bridge_en)"
>> block statement to fix (on Ubuntu):
>>
>>   ../hw/i386/acpi-build.c: In function 'build_append_pci_bus_devices':
>>   ../hw/i386/acpi-build.c:496:9: error: 'method' may be used uninitialized
>>   in this function [-Werror=maybe-uninitialized]
>>     496 |         aml_append(parent_scope, method);
>>         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>   cc1: all warnings being treated as errors
> 
> OK I looked at the patch closely and it makes sense. Can you please
> run a "make check" to make sure we have not broken anything?

Yes I did...

Re: [PATCH-for-5.2 v2] hw/i386/acpi-build: Fix maybe-uninitialized error when ACPI hotplug off

[Ani Sinha]

[-- Attachment #1: Type: text/plain, Size: 1137 bytes --]

On Sun, Nov 8, 2020 at 22:40 Philippe Mathieu-Daudé <philmd@redhat.com>
wrote:

> On 11/8/20 4:58 AM, Ani Sinha wrote:
> > On Sun, Nov 8, 2020 at 1:10 AM Philippe Mathieu-Daudé <philmd@redhat.com>
> wrote:
> >>
> >> GCC 9.3.0 thinks that 'method' can be left uninitialized. This code
> >> is already in the "if (bsel || pcihp_bridge_en)" block statement,
> >> but it isn't smart enough to figure it out.
> >>
> >> Restrict the code to be used only in the "if (bsel || pcihp_bridge_en)"
> >> block statement to fix (on Ubuntu):
> >>
> >>   ../hw/i386/acpi-build.c: In function 'build_append_pci_bus_devices':
> >>   ../hw/i386/acpi-build.c:496:9: error: 'method' may be used
> uninitialized
> >>   in this function [-Werror=maybe-uninitialized]
> >>     496 |         aml_append(parent_scope, method);
> >>         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >>   cc1: all warnings being treated as errors
> >
> > OK I looked at the patch closely and it makes sense. Can you please
> > run a "make check" to make sure we have not broken anything?
>
> Yes I did...


Has this been queued Michael?


>
>

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Re: [PATCH-for-5.2 v2] hw/i386/acpi-build: Fix maybe-uninitialized error when ACPI hotplug off

[Michael S. Tsirkin]

On Thu, Nov 12, 2020 at 09:21:47AM +0530, Ani Sinha wrote:
> 
> 
> On Sun, Nov 8, 2020 at 22:40 Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
> 
>     On 11/8/20 4:58 AM, Ani Sinha wrote:
>     > On Sun, Nov 8, 2020 at 1:10 AM Philippe Mathieu-Daudé <philmd@redhat.com>
>     wrote:
>     >>
>     >> GCC 9.3.0 thinks that 'method' can be left uninitialized. This code
>     >> is already in the "if (bsel || pcihp_bridge_en)" block statement,
>     >> but it isn't smart enough to figure it out.
>     >>
>     >> Restrict the code to be used only in the "if (bsel || pcihp_bridge_en)"
>     >> block statement to fix (on Ubuntu):
>     >>
>     >>   ../hw/i386/acpi-build.c: In function 'build_append_pci_bus_devices':
>     >>   ../hw/i386/acpi-build.c:496:9: error: 'method' may be used
>     uninitialized
>     >>   in this function [-Werror=maybe-uninitialized]
>     >>     496 |         aml_append(parent_scope, method);
>     >>         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>     >>   cc1: all warnings being treated as errors
>     >
>     > OK I looked at the patch closely and it makes sense. Can you please
>     > run a "make check" to make sure we have not broken anything?
> 
>     Yes I did...
> 
> 
> Has this been queued Michael?

tagged, thanks!

> 
> 
> 
>