Re: [PATCH v2 09/64] dmaengine: ioat: convert cleanup tasklet to dma_chan BH

[Dave Jiang <dave.jiang@intel.com>]

On 7/27/26 1:28 PM, Allen Pais wrote:
> Replace the per-channel tasklet with the shared dma_chan BH helper.
> The handler continues to run in softirq context while dmaengine owns
> the common scheduling and teardown mechanism.
> 
> Signed-off-by: Allen Pais <allen.lkml@gmail.com>

Acked-by: Dave Jiang <dave.jiang@intel.com>


> ---
>  drivers/dma/ioat/dma.c  | 14 +++++++-------
>  drivers/dma/ioat/dma.h  |  3 +--
>  drivers/dma/ioat/init.c |  2 +-
>  3 files changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c
> index ee93b029f9e3..827b46c6354a 100644
> --- a/drivers/dma/ioat/dma.c
> +++ b/drivers/dma/ioat/dma.c
> @@ -110,7 +110,7 @@ irqreturn_t ioat_dma_do_interrupt(int irq, void *data)
>  	for_each_set_bit(bit, &attnstatus, BITS_PER_LONG) {
>  		ioat_chan = ioat_chan_by_index(instance, bit);
>  		if (test_bit(IOAT_RUN, &ioat_chan->state))
> -			tasklet_schedule(&ioat_chan->cleanup_task);
> +			dma_chan_schedule_bh(&ioat_chan->dma_chan);
>  	}
>  
>  	writeb(intrctrl, instance->reg_base + IOAT_INTRCTRL_OFFSET);
> @@ -127,7 +127,7 @@ irqreturn_t ioat_dma_do_interrupt_msix(int irq, void *data)
>  	struct ioatdma_chan *ioat_chan = data;
>  
>  	if (test_bit(IOAT_RUN, &ioat_chan->state))
> -		tasklet_schedule(&ioat_chan->cleanup_task);
> +		dma_chan_schedule_bh(&ioat_chan->dma_chan);
>  
>  	return IRQ_HANDLED;
>  }
> @@ -161,11 +161,11 @@ void ioat_stop(struct ioatdma_chan *ioat_chan)
>  	/* flush inflight timers */
>  	timer_delete_sync(&ioat_chan->timer);
>  
> -	/* flush inflight tasklet runs */
> -	tasklet_kill(&ioat_chan->cleanup_task);
> +	/* flush inflight BH runs */
> +	dma_chan_kill_bh(&ioat_chan->dma_chan);
>  
>  	/* final cleanup now that everything is quiesced and can't re-arm */
> -	ioat_cleanup_event(&ioat_chan->cleanup_task);
> +	ioat_cleanup_event(&ioat_chan->dma_chan);
>  }
>  
>  static void __ioat_issue_pending(struct ioatdma_chan *ioat_chan)
> @@ -690,9 +690,9 @@ static void ioat_cleanup(struct ioatdma_chan *ioat_chan)
>  	spin_unlock_bh(&ioat_chan->cleanup_lock);
>  }
>  
> -void ioat_cleanup_event(struct tasklet_struct *t)
> +void ioat_cleanup_event(struct dma_chan *c)
>  {
> -	struct ioatdma_chan *ioat_chan = from_tasklet(ioat_chan, t, cleanup_task);
> +	struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
>  
>  	ioat_cleanup(ioat_chan);
>  	if (!test_bit(IOAT_RUN, &ioat_chan->state))
> diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
> index e8a880f338c6..4bdb1ae937e4 100644
> --- a/drivers/dma/ioat/dma.h
> +++ b/drivers/dma/ioat/dma.h
> @@ -111,7 +111,6 @@ struct ioatdma_chan {
>  	struct ioatdma_device *ioat_dma;
>  	dma_addr_t completion_dma;
>  	u64 *completion;
> -	struct tasklet_struct cleanup_task;
>  	struct kobject kobj;
>  
>  /* ioat v2 / v3 channel attributes
> @@ -385,7 +384,7 @@ int ioat_reset_hw(struct ioatdma_chan *ioat_chan);
>  enum dma_status
>  ioat_tx_status(struct dma_chan *c, dma_cookie_t cookie,
>  		struct dma_tx_state *txstate);
> -void ioat_cleanup_event(struct tasklet_struct *t);
> +void ioat_cleanup_event(struct dma_chan *c);
>  void ioat_timer_event(struct timer_list *t);
>  int ioat_check_space_lock(struct ioatdma_chan *ioat_chan, int num_descs);
>  void ioat_issue_pending(struct dma_chan *chan);
> diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c
> index 737496391109..314676e1cbc4 100644
> --- a/drivers/dma/ioat/init.c
> +++ b/drivers/dma/ioat/init.c
> @@ -765,7 +765,7 @@ ioat_init_channel(struct ioatdma_device *ioat_dma,
>  	list_add_tail(&ioat_chan->dma_chan.device_node, &dma->channels);
>  	ioat_dma->idx[idx] = ioat_chan;
>  	timer_setup(&ioat_chan->timer, ioat_timer_event, 0);
> -	tasklet_setup(&ioat_chan->cleanup_task, ioat_cleanup_event);
> +	dma_chan_init_bh(&ioat_chan->dma_chan, ioat_cleanup_event);
>  }
>  
>  #define IOAT_NUM_SRC_TEST 6 /* must be <= 8 */