Re: [PATCH v1 07/10] hw/i386/acpi-build: Fix maybe-uninitialized error when ACPI hotplug off

[Igor Mammedov]

On Tue, 10 Nov 2020 19:23:13 +0000
Alex Bennée <alex.bennee@linaro.org> wrote:

> From: Philippe Mathieu-Daudé <philmd@redhat.com>
> 
> 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>
> Message-Id: <20201108204535.2319870-4-philmd@redhat.com>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  hw/i386/acpi-build.c | 41 +++++++++++++++++++----------------------
>  1 file changed, 19 insertions(+), 22 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 4f66642d88..1f5c211245 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;
> +            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 (pci_bus_is_root(sec) || pci_bus_is_express(sec)) {
> -                continue;
> -            }
> +        /* 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_name("^S%.02X.PCNT", devfn));
> +            }
>          }
> -    }
>  
> -    if (bsel || pcihp_bridge_en) {
>          aml_append(parent_scope, method);
>      }
>      qobject_unref(bsel);