Re: [Qemu-devel] [Qemu-block] segfault in parallel blockjobs (iotest 30)

[Alberto Garcia]

On Thu 09 Nov 2017 07:05:26 AM CET, Fam Zheng wrote:

>> > I can fix the crash by adding block_job_pause_point(&s->common) at
>> > the end of stream_run() (where the 'out' label is).
>> > 
>> > I'm thinking that perhaps we should add the pause point directly to
>> > block_job_defer_to_main_loop(), to prevent any block job from
>> > running the exit function when it's paused.
>> > 
>> 
>> Is it possible that the exit function is already deferred when the
>> jobs are being paused? (even though it's at least less likely to
>> happen)
>> 
>> Then should we flush the bottom halves somehow in addition to putting
>> the jobs to sleep? And also then it all probably has to happen before
>> bdrv_reopen_queue()
>
> Or we can stash away the BH temporarily during pause period:
>
> ---
>
> diff --git a/blockjob.c b/blockjob.c
> index 3a0c49137e..7058ff7ae1 100644

Yeah, what you suggest sounds good. We would still need to add a pause
point in addition to this.

Does this sound good to everyone? If so I can prepare the patches.

Berto