[PATCH 10/55] hyperv: use g_autoptr for Msvm_ProcessorSettingData in hypervConnectGetMaxVcpus

[Laine Stump]

On 1/21/21 1:50 PM, Matt Coleman wrote:
> Signed-off-by: Matt Coleman <matt at datto.com>
> ---
>   src/hyperv/hyperv_driver.c | 14 ++++----------
>   1 file changed, 4 insertions(+), 10 deletions(-)
>
> diff --git a/src/hyperv/hyperv_driver.c b/src/hyperv/hyperv_driver.c
> index 8b59dd05f7..6375f6b011 100644
> --- a/src/hyperv/hyperv_driver.c
> +++ b/src/hyperv/hyperv_driver.c
> @@ -1514,10 +1514,9 @@ hypervConnectGetCapabilities(virConnectPtr conn)
>   static int
>   hypervConnectGetMaxVcpus(virConnectPtr conn, const char *type G_GNUC_UNUSED)
>   {
> -    int result = -1;
>       hypervPrivate *priv = conn->privateData;
>       g_auto(virBuffer) query = VIR_BUFFER_INITIALIZER;
> -    Msvm_ProcessorSettingData *processorSettingData = NULL;
> +    g_autoptr(Msvm_ProcessorSettingData) processorSettingData = NULL;
>   
>       /* Get max processors definition */
>       virBufferAddLit(&query,
> @@ -1525,21 +1524,16 @@ hypervConnectGetMaxVcpus(virConnectPtr conn, const char *type G_GNUC_UNUSED)
>                       "WHERE InstanceID LIKE 'Microsoft:Definition%Maximum'");
>   
>       if (hypervGetWmiClass(Msvm_ProcessorSettingData, &processorSettingData) < 0)
> -        goto cleanup;
> +        return -1;
>   
>       if (!processorSettingData) {
>           virReportError(VIR_ERR_INTERNAL_ERROR,
>                          _("Could not get maximum definition of Msvm_ProcessorSettingData for host %s"),
>                          conn->uri->server);
> -        goto cleanup;
> +        return -1;
>       }
>   
> -    result = processorSettingData->data->VirtualQuantity;
> -
> - cleanup:
> -    hypervFreeObject((hypervObject *)processorSettingData);
> -
> -    return result;
> +    return processorSettingData->data->VirtualQuantity;


So. Something I'm unsure of - what you're doing here is returning a 
value that is stored in an object that is being auto-freed by the 
cleanup when the scope of the function is exited. I *guess* that the 
cleanup happens after copying the return value into the register that's 
used to return it to the caller? But I'm not sure, and it could just as 
easily be done in the opposite order. It's too late in the day (early in 
the next day, actually) for me to compile something and look at it with 
gdb to verify. Anybody else know the answer (or feel like experimenting)?


>   }
>   
>