linux-kernel - Re: [PATCH 2/2] dmaengine: idxd: track enabled workqueues in bitmap

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Date:   Wed, 28 Sep 2022 08:21:20 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Vinod Koul <vkoul@...nel.org>
Subject: Re: [PATCH 2/2] dmaengine: idxd: track enabled workqueues in bitmap

On Mon, Sep 19, 2022 at 02:55:53PM -0700, Jerry Snitselaar wrote:
> Now that idxd_wq_disable_cleanup() sets the workqueue state to
> IDXD_WQ_DISABLED, use a bitmap to track which workqueues have been
> enabled. This will then be used to determine which workqueues
> should be re-enabled when attempting a software reset to recover
> from a device halt state.
> 
> Cc: Fenghua Yu <fenghua.yu@...el.com>
> Cc: Dave Jiang <dave.jiang@...el.com>
> Cc: Vinod Koul <vkoul@...nel.org>
> Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>
> ---
>  drivers/dma/idxd/device.c | 2 ++
>  drivers/dma/idxd/idxd.h   | 2 ++
>  drivers/dma/idxd/init.c   | 6 ++++++
>  drivers/dma/idxd/irq.c    | 4 ++--
>  drivers/dma/idxd/sysfs.c  | 1 +
>  5 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 31911e255ac1..f0c7d6d348e3 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -196,6 +196,7 @@ int idxd_wq_enable(struct idxd_wq *wq)
>  	}
>  
>  	wq->state = IDXD_WQ_ENABLED;
> +	set_bit(wq->id, idxd->wq_enable_map);
>  	dev_dbg(dev, "WQ %d enabled\n", wq->id);
>  	return 0;
>  }
> @@ -223,6 +224,7 @@ int idxd_wq_disable(struct idxd_wq *wq, bool reset_config)
>  
>  	if (reset_config)
>  		idxd_wq_disable_cleanup(wq);
> +	clear_bit(wq->id, idxd->wq_enable_map);
>  	wq->state = IDXD_WQ_DISABLED;
>  	dev_dbg(dev, "WQ %d disabled\n", wq->id);
>  	return 0;
> diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
> index fed0dfc1eaa8..f527a7f88b92 100644
> --- a/drivers/dma/idxd/idxd.h
> +++ b/drivers/dma/idxd/idxd.h
> @@ -11,6 +11,7 @@
>  #include <linux/idr.h>
>  #include <linux/pci.h>
>  #include <linux/ioasid.h>
> +#include <linux/bitmap.h>
>  #include <linux/perf_event.h>
>  #include <uapi/linux/idxd.h>
>  #include "registers.h"
> @@ -299,6 +300,7 @@ struct idxd_device {
>  	int rdbuf_limit;
>  	int nr_rdbufs;		/* non-reserved read buffers */
>  	unsigned int wqcfg_size;
> +	unsigned long *wq_enable_map;
>  
>  	union sw_err_reg sw_err;
>  	wait_queue_head_t cmd_waitq;
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index aa3478257ddb..7e27e69ff741 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -151,6 +151,12 @@ static int idxd_setup_wqs(struct idxd_device *idxd)
>  	if (!idxd->wqs)
>  		return -ENOMEM;
>  
> +	idxd->wq_enable_map = bitmap_zalloc_node(idxd->max_wqs, GFP_KERNEL, dev_to_node(dev));
> +	if (!idxd->wq_enable_map) {
> +		kfree(idxd->wqs);
> +		return -ENOMEM;
> +	}
> +
>  	for (i = 0; i < idxd->max_wqs; i++) {
>  		wq = kzalloc_node(sizeof(*wq), GFP_KERNEL, dev_to_node(dev));
>  		if (!wq) {
> diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
> index 743ead5ebc57..8efaf137fc65 100644
> --- a/drivers/dma/idxd/irq.c
> +++ b/drivers/dma/idxd/irq.c
> @@ -49,9 +49,9 @@ static void idxd_device_reinit(struct work_struct *work)
>  		goto out;
>  
>  	for (i = 0; i < idxd->max_wqs; i++) {
> -		struct idxd_wq *wq = idxd->wqs[i];
> +		if (test_bit(i, idxd->wq_enable_map)) {
> +			struct idxd_wq *wq = idxd->wqs[i];
>  
> -		if (wq->state == IDXD_WQ_ENABLED) {
>  			rc = idxd_wq_enable(wq);
>  			if (rc < 0) {
>  				dev_warn(dev, "Unable to re-enable wq %s\n",

Hi Dave and Fenghua,

Thinking about this last night, this should probably clear the bit here in
the case where an error is returned from idxd_wq_enable here, yes? I can
send a v2.


> diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
> index 3f262a57441b..3325b16ed959 100644
> --- a/drivers/dma/idxd/sysfs.c
> +++ b/drivers/dma/idxd/sysfs.c
> @@ -1405,6 +1405,7 @@ static void idxd_conf_device_release(struct device *dev)
>  	struct idxd_device *idxd = confdev_to_idxd(dev);
>  
>  	kfree(idxd->groups);
> +	bitmap_free(idxd->wq_enable_map);
>  	kfree(idxd->wqs);
>  	kfree(idxd->engines);
>  	ida_free(&idxd_ida, idxd->id);
> -- 
> 2.37.2
>