Re: [PATCH] block: mq flush: fix race between IPI handler and mq flush worker

From: Christoph Hellwig
Date: Mon May 19 2014 - 11:18:34 EST


On Mon, May 19, 2014 at 11:05:50PM +0800, Ming Lei wrote:
> Another simple fix is to disable ipi for flush request, but looks
> this one should be better.

I think the first thing is to bite the bullet and sort out and document
the various unions in struct request for real.

For example the first union has the call_single_data for the blk-mq
completions, while the second one has the ipi_list that is used by
the old blk-softirq code.

If we get this right with a single union that contains a struct for
each phase of the request we might find enough space to keep using
the current way.


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