Re: [Qemu-devel] [Qemu-block] [PATCH 1/2] blockjob: Rename block_job_defer_to_main_loop

[Stefan Hajnoczi]

On Thu, Jan 28, 2016 at 03:02:50PM +0800, Fam Zheng wrote:
> diff --git a/include/block/blockjob.h b/include/block/blockjob.h
> index d84ccd8..de59fc2 100644
> --- a/include/block/blockjob.h
> +++ b/include/block/blockjob.h
> @@ -393,18 +393,20 @@ BlockErrorAction block_job_error_action(BlockJob *job, 
> BlockDriverState *bs,
>  typedef void BlockJobDeferToMainLoopFn(BlockJob *job, void *opaque);
>  
>  /**
> - * block_job_defer_to_main_loop:
> + * block_job_coroutine_complete:
>   * @job: The job
>   * @fn: The function to run in the main loop
>   * @opaque: The opaque value that is passed to @fn
>   *
> - * Execute a given function in the main loop with the BlockDriverState
> - * AioContext acquired.  Block jobs must call bdrv_unref(), bdrv_close(), and
> - * anything that uses bdrv_drain_all() in the main loop.
> + * Complete the block job coroutine and execute a given function in the main

This function does not "complete the block job coroutine" so this seems
confusing to me.  How about "Call this function to schedule clean up
code to run in the main loop when completing a block job"?

That said, I'm not sure if changing the scope of this function is
necessary at all.  If the next patch adds a job->aio_context pointer
then it could set the pointer back after calling the user's function
from the main loop.  Then this function could also be used in cases
where the job/coroutine stays alive.

> + * loop with the BlockDriverState AioContext acquired.  Block jobs must call
> + * bdrv_unref(), bdrv_close(), and anything that uses bdrv_drain_all() in the
> + * main loop. After calling this, the block job coroutine should complete 
> right
> + * away, without doing any heavy operations such as I/O or block_job_yield().

"heavy operations" is too vague.  What are the specific constraints
here?

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