Re: [Qemu-arm] [Qemu-devel] [PATCH 1/5] xilinx: Fix error handling

[Markus Armbruster]

Eduardo Habkost <address@hidden> writes:

> On Wed, Jul 05, 2017 at 01:44:35PM +0200, Markus Armbruster wrote:
>> Eduardo Habkost <address@hidden> writes:
>> 
>> > Assigning directly to *errp is not valid, as errp may be NULL,
>> > &error_fatal, or &error_abort.  Use error_propagate() instead.
>> >
>> > error_propagate() handles non-NULL *errp correctly, so the
>> > "if (!*errp)" check can be removed.
>> >
>> > Cc: "Edgar E. Iglesias" <address@hidden>
>> > Cc: Alistair Francis <address@hidden>
>> > Cc: Jason Wang <address@hidden>
>> > Cc: address@hidden
>> > Signed-off-by: Eduardo Habkost <address@hidden>
>> > ---
>> >  hw/dma/xilinx_axidma.c  | 4 +---
>> >  hw/net/xilinx_axienet.c | 4 +---
>> >  2 files changed, 2 insertions(+), 6 deletions(-)
>> >
>> > diff --git a/hw/dma/xilinx_axidma.c b/hw/dma/xilinx_axidma.c
>> > index 6065689ad1..3987b5ff96 100644
>> > --- a/hw/dma/xilinx_axidma.c
>> > +++ b/hw/dma/xilinx_axidma.c
>> > @@ -554,9 +554,7 @@ static void xilinx_axidma_realize(DeviceState *dev, 
>> > Error **errp)
>> >      return;
>> >  
>> >  xilinx_axidma_realize_fail:
>> > -    if (!*errp) {
>> > -        *errp = local_err;
>> > -    }
>> > +    error_propagate(errp, local_err);
>> >  }
>> >  
>> >  static void xilinx_axidma_init(Object *obj)
>> > diff --git a/hw/net/xilinx_axienet.c b/hw/net/xilinx_axienet.c
>> > index b6701844d3..5ffa739f68 100644
>> > --- a/hw/net/xilinx_axienet.c
>> > +++ b/hw/net/xilinx_axienet.c
>> > @@ -981,9 +981,7 @@ static void xilinx_enet_realize(DeviceState *dev, 
>> > Error **errp)
>> >      return;
>> >  
>> >  xilinx_enet_realize_fail:
>> > -    if (!*errp) {
>> > -        *errp = local_err;
>> > -    }
>> > +    error_propagate(errp, local_err);
>> >  }
>> >  
>> >  static void xilinx_enet_init(Object *obj)
>> 
>> The qdev core always passes &err.  So this is "merely" a fix for a
>> latent bug.
>> 
>> If it could pass null, you'd fix a crash bug.
>> 
>> If it could pass pointer to non-null (&error_fatal, &error_abort), you'd
>> plug a memory leak.
>> 
>> Suggest to rephrase the commit message:
>> 
>>     xilinx: Fix latent error handling bug
>> 
>>     Assigning directly to *errp is not valid, as errp may be null,
>>     &error_fatal, or &error_abort.  The !*errp conditional protects
>>     against the latter two, but we then leak @local_err.  Fortunately,
>>     the qdev core always passes pointer to null, so this is "merely" a
>>     latent bug.
>> 
>>     Use error_propagate() instead.
>> 
>> What do you think?
>
> Looks good to me.  Do you want to fix it when applying?

Can do!

>> With something like that:
>> Reviewed-by: Markus Armbruster <address@hidden>
>
> Thanks!