[v2,12/12] pc-dimm: get_memory_region() will not fail after realize

Let's try to reduce error handling a bit. In the plug/unplug case, the
device was realized and therefore we can assume that getting access to
the memory region will not fail.

For get_vmstate_memory_region() this is already handled that way.
Document both cases.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/i386/pc.c             |  7 +------
 hw/mem/pc-dimm.c         |  7 +------
 hw/ppc/spapr.c           | 12 ++----------
 include/hw/mem/pc-dimm.h |  6 ++++--
 4 files changed, 8 insertions(+), 24 deletions(-)

On Fri, 15 Jun 2018 13:25:00 +0200
David Hildenbrand <david@redhat.com> wrote:

> Let's try to reduce error handling a bit. In the plug/unplug case, the
> device was realized and therefore we can assume that getting access to
> the memory region will not fail.
> 
> For get_vmstate_memory_region() this is already handled that way.
> Document both cases.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

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

> ---
>  hw/i386/pc.c             |  7 +------
>  hw/mem/pc-dimm.c         |  7 +------
>  hw/ppc/spapr.c           | 12 ++----------
>  include/hw/mem/pc-dimm.h |  6 ++++--
>  4 files changed, 8 insertions(+), 24 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 2db032a6df..f310040351 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1706,15 +1706,10 @@ static void pc_memory_plug(HotplugHandler *hotplug_dev,
>      PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
>      PCDIMMDevice *dimm = PC_DIMM(dev);
>      PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
> -    MemoryRegion *mr;
> +    MemoryRegion *mr = ddc->get_memory_region(dimm, &error_abort);
>      uint64_t align = TARGET_PAGE_SIZE;
>      bool is_nvdimm = object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM);
>  
> -    mr = ddc->get_memory_region(dimm, &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
> -
>      if (memory_region_get_alignment(mr) && pcmc->enforce_aligned_dimm) {
>          align = memory_region_get_alignment(mr);
>      }
> diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
> index 4ff39b59ef..65843bc52a 100644
> --- a/hw/mem/pc-dimm.c
> +++ b/hw/mem/pc-dimm.c
> @@ -37,15 +37,10 @@ void pc_dimm_plug(DeviceState *dev, MachineState *machine, uint64_t align,
>      PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
>      MemoryRegion *vmstate_mr = ddc->get_vmstate_memory_region(dimm,
>                                                                &error_abort);
> +    MemoryRegion *mr = ddc->get_memory_region(dimm, &error_abort);
>      Error *local_err = NULL;
> -    MemoryRegion *mr;
>      uint64_t addr;
>  
> -    mr = ddc->get_memory_region(dimm, &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
> -
>      addr = object_property_get_uint(OBJECT(dimm),
>                                      PC_DIMM_ADDR_PROP, &local_err);
>      if (local_err) {
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 3e5320020f..6934abc21e 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -3142,14 +3142,10 @@ static void spapr_memory_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>      sPAPRMachineState *ms = SPAPR_MACHINE(hotplug_dev);
>      PCDIMMDevice *dimm = PC_DIMM(dev);
>      PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
> -    MemoryRegion *mr;
> +    MemoryRegion *mr = ddc->get_memory_region(dimm, &error_abort);
>      uint64_t align, size, addr;
>      uint32_t node;
>  
> -    mr = ddc->get_memory_region(dimm, &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
>      align = memory_region_get_alignment(mr);
>      size = memory_region_size(mr);
>  
> @@ -3340,16 +3336,12 @@ static void spapr_memory_unplug_request(HotplugHandler *hotplug_dev,
>      Error *local_err = NULL;
>      PCDIMMDevice *dimm = PC_DIMM(dev);
>      PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
> -    MemoryRegion *mr;
> +    MemoryRegion *mr = ddc->get_memory_region(dimm, &error_abort);
>      uint32_t nr_lmbs;
>      uint64_t size, addr_start, addr;
>      int i;
>      sPAPRDRConnector *drc;
>  
> -    mr = ddc->get_memory_region(dimm, &local_err);
> -    if (local_err) {
> -        goto out;
> -    }
>      size = memory_region_size(mr);
>      nr_lmbs = size / SPAPR_MEMORY_BLOCK_SIZE;
>  
> diff --git a/include/hw/mem/pc-dimm.h b/include/hw/mem/pc-dimm.h
> index 5679a80465..26ebb7d5e9 100644
> --- a/include/hw/mem/pc-dimm.h
> +++ b/include/hw/mem/pc-dimm.h
> @@ -62,9 +62,11 @@ typedef struct PCDIMMDevice {
>   * @realize: called after common dimm is realized so that the dimm based
>   * devices get the chance to do specified operations.
>   * @get_memory_region: returns #MemoryRegion associated with @dimm which
> - * is directly mapped into the physical address space of guest.
> + * is directly mapped into the physical address space of guest. Will not
> + * fail after the device was realized.
>   * @get_vmstate_memory_region: returns #MemoryRegion which indicates the
> - * memory of @dimm should be kept during live migration.
> + * memory of @dimm should be kept during live migration. Will not fail
> + * after the device was realized.
>   */
>  typedef struct PCDIMMDeviceClass {
>      /* private */