Re: [Qemu-devel] [PATCH 1/2] blockjob: assert(cb) in the entry functions of blockjob

[Eric Blake]

On 06/22/2016 04:19 AM, Paolo Bonzini wrote:
> 
> 
> On 22/06/2016 12:12, Changlong Xie wrote:
>>
>> commit/mirror/stream/backup use block_job_create(..., cb,..) to create
>> relevant blockjob. When they finished, these jobs will invoke
>> block_job_completed, then invoke job->cb() unconditionally. So i think
>> we need this to avoid segment fault. Actually backup has implemented this.
> 
> So this suggests that the right place to put the assertion would be
> block_job_create.  But it's even better to add a
> 
> #define QEMU_NONNULL __attribute__((__nonnull__))
> 
> to include/qemu/compiler.h and declare the arguments as non-null.

Or alternatively fix things to only invoke job->cb() if it is non-NULL,
so that callers don't have to pass in a no-op callback just to appease a
non-NULL attribute.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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