Re: [Qemu-devel] [PATCH] Fix memory leak on error

[Stefano Dong <opensource.dxs@aliyun.com>]

On 2015/11/26 20:33, Markus Armbruster wrote:
> Stefano Dong (董兴水) <opensource.dxs@aliyun.com> writes:
> 
>> hw/ppc/spapr.c: Fix memory leak on error, it was introduced in bc09e0611
>> hw/acpi/memory_hotplug.c: Fix memory leak on error, it was introduced in 34f2af3d
>>
>> Signed-off-by: Stefano Dong (董兴水) <opensource.dxs@aliyun.com>
>> ---
>>  hw/acpi/memory_hotplug.c | 1 +
>>  hw/ppc/spapr.c           | 1 +
>>  2 files changed, 2 insertions(+)
>>
>> diff --git a/hw/acpi/memory_hotplug.c b/hw/acpi/memory_hotplug.c
>> index ce428df..e4b9a01 100644
>> --- a/hw/acpi/memory_hotplug.c
>> +++ b/hw/acpi/memory_hotplug.c
>> @@ -155,6 +155,7 @@ static void acpi_memory_hotplug_write(void *opaque, hwaddr addr, uint64_t data,
>>                  qapi_event_send_mem_unplug_error(dev->id,
>>                                                   error_get_pretty(local_err),
>>                                                   &error_abort);
>> +                error_free(local_err);
>>                  break;
>>              }
>>              trace_mhp_acpi_pc_dimm_deleted(mem_st->selector);
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index 030ee35..3bb8bcd 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -125,6 +125,7 @@ static XICSState *xics_system_init(MachineState *machine,
>>              error_report("kernel_irqchip requested but unavailable: %s",
>>                           error_get_pretty(err));
>>          }
>> +        error_free(err);
>>      }
>>  
>>      if (!icp) {
> 
> Two independent instances of the same kind of bug (failure to free an
> Error after handling it).  Collecting multiple fixes of the same kind in
> one patch can be fine.  Note, however, that the combined patch spans
> separately maintained areas of the code:
> 
>     $ scripts/get_maintainer.pl -f hw/acpi/memory_hotplug.c 
>     "Michael S. Tsirkin" <mst@redhat.com> (supporter:ACPI/SMBIOS)
>     Igor Mammedov <imammedo@redhat.com> (supporter:ACPI/SMBIOS)
>     $ scripts/get_maintainer.pl -f hw/ppc/spapr.c 
>     David Gibson <david@gibson.dropbear.id.au> (supporter:sPAPR (pseries))
>     Alexander Graf <agraf@suse.de> (supporter:sPAPR (pseries))
>     Eduardo Habkost <ehabkost@redhat.com> (maintainer:NUMA)
>     qemu-ppc@nongnu.org (open list:sPAPR (pseries))
> 
> If the combined patch is trivial, cc: qemu-trivial@nongnu.org.  I figure
> this one could qualify.
> 
> If it isn't, split it up along mainenance boundaries, and cc: the
> maintainer(s) for each part.
> 
> When you fix something with serious impact, the commit message should
> give a clue when it was broken.  For minor bugs like these, it's still
> nice to do.  The acpi_memory_hotplug_write() leak was introduced in
> bc09e06 (v2.4.0), and the xics_system_init() leak in commit 34f2af3
> (v2.3.0).  Thanks for fixing the mess I made there, by the way.
> 
> Since this is a straightforward bug fix, proposing it for inclusion into
> 2.5 makes sense.  You can do that by putting [PATCH for-2.5] into the
> subject.

Thank you Markus! Thanks for teaching me a lot! You are so kind and friendly!

>