Re: [PATCH v3] mmc: Convert from tasklet to BH workqueue

On Tue, Jun 18, 2024 at 03:52:07PM GMT, Allen Pais wrote:

quoted

The only generic interface to execute asynchronously in the BH context is
tasklet; however, it's marked deprecated and has some design flaws. To
replace tasklets, BH workqueue support was recently added. A BH workqueue
behaves similarly to regular workqueues except that the queued work items
are executed in the BH context.

This patch converts drivers/mmc/* from tasklet to BH workqueue.

Based on the work done by Tejun Heo [off-list ref]

Has this been fully build-tested?

===
drivers/mmc/host/renesas_sdhi_internal_dmac.c: In function ‘renesas_sdhi_internal_dmac_complete_work_fn’:
./include/linux/container_of.h:20:54: error: ‘struct tmio_mmc_host’ has no member named ‘dma_complete’
===

 Yes, it does break. My bad, my local compile testing failed to catch this.

In deed, 'dma_complete' is only in 'struct renesas_sdhi_dma'. From
there, we can get to the parent 'struct renesas_sdhi' using
container_of. But then, I don't see a way to go to 'struct
tmio_mmc_host' from there. The other way around is possible because
there is the pointer 'struct tmio_mmc_data *pdata' in the TMIO struct
pointing to the data contained in 'struct renesas_sdhi'. 'host_to_priv()'
does the math. But I don't see a path the other way around.

 I have been looking at this code since the issue was reported. Yes it
is a bit tricky and so far, the only way I found was to introduce a new pointer.
But, I am not very familiar with the code and have asked Ulf for pointers.

If introducing the pointer is the only way forward and is an
acceptable solution,
I can send out a draft.

Thanks,
Allen

So, it doesn't look like the workqueue interface can provide a
generic pointer like tasklets could do? This means we have to add a
pointer from 'struct renesas_sdhi' to 'struct tmio_mmc_host'?

All the best,

   Wolfram

-- 
       - Allen