Re: [PATCH v16 5/5] fpga: image-load: enable cancel of image upload

[Xu Yilun]

On Wed, Sep 22, 2021 at 05:10:56PM -0700, Russ Weight wrote:
> Extend the FPGA Image Load framework to include a cancel IOCTL that can be
> used to request that an image upload be canceled. The IOCTL may return
> EBUSY if it cannot be canceled by software or ENODEV if there is no update
> in progress.
> 
> Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
> ---
> v16:
>  - This was previously patch 6/6
>  - Amend fpga_image_load_release() to request cancellation of an ongoing
>    update when possible.
> v15:
>  - Compare to previous patch:
>      [PATCH v14 6/6] fpga: sec-mgr: enable cancel of secure update
>  - Changed file, symbol, and config names to reflect the new driver name
>  - Cancel is now initiated by IOCT instead of sysfs
>  - Removed signed-off/reviewed-by tags
> v14:
>  - Updated ABI documentation date and kernel version
> v13:
>   - No change
> v12:
>   - Updated Date and KernelVersion fields in ABI documentation
> v11:
>   - No change
> v10:
>   - Rebased to 5.12-rc2 next
>   - Updated Date and KernelVersion in ABI documentation
> v9:
>   - Updated Date and KernelVersion in ABI documentation
> v8:
>   - No change
> v7:
>   - Changed Date in documentation file to December 2020
> v6:
>   - No change
> v5:
>   - No change
> v4:
>   - Changed from "Intel FPGA Security Manager" to FPGA Security Manager"
>     and removed unnecessary references to "Intel".
>   - Changed: iops -> sops, imgr -> smgr, IFPGA_ -> FPGA_, ifpga_ to fpga_
> v3:
>   - No change
> v2:
>   - Bumped documentation date and version
>   - Minor code cleanup per review comments
> ---
>  Documentation/fpga/fpga-image-load.rst |  6 ++++
>  drivers/fpga/fpga-image-load.c         | 49 +++++++++++++++++++++++---
>  include/linux/fpga/fpga-image-load.h   |  1 +
>  include/uapi/linux/fpga-image-load.h   |  2 ++
>  4 files changed, 53 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/fpga/fpga-image-load.rst b/Documentation/fpga/fpga-image-load.rst
> index 572e18afebb9..21fa85f18680 100644
> --- a/Documentation/fpga/fpga-image-load.rst
> +++ b/Documentation/fpga/fpga-image-load.rst
> @@ -40,3 +40,9 @@ FPGA_IMAGE_LOAD_STATUS:
>  Collect status for an on-going image upload. The status returned includes
>  how much data remains to be transferred, the progress of the image load,
>  and error information in the case of a failure.
> +
> +FPGA_IMAGE_LOAD_CANCEL:
> +
> +Request that a on-going image upload be cancelled. This IOCTL may return

		an

> +EBUSY if it cannot be cancelled by software or ENODEV if there is no update

   -EBUSY					 -ENODEV

> +in progress.
> diff --git a/drivers/fpga/fpga-image-load.c b/drivers/fpga/fpga-image-load.c
> index 2e9a5a041535..a95d18077d58 100644
> --- a/drivers/fpga/fpga-image-load.c
> +++ b/drivers/fpga/fpga-image-load.c
> @@ -46,6 +46,24 @@ static void fpga_image_dev_error(struct fpga_image_load *imgld, u32 err_code)
>  	imgld->ops->cancel(imgld);
>  }
>  
> +static int fpga_image_prog_transition(struct fpga_image_load *imgld,
> +				      u32 new_progress)
> +{
> +	int ret = 0;
> +
> +	mutex_lock(&imgld->lock);
> +	if (imgld->request_cancel) {
> +		imgld->err_progress = imgld->progress;
> +		imgld->err_code = FPGA_IMAGE_ERR_CANCELED;
> +		imgld->ops->cancel(imgld);

We could only cancel in 2 conditions.
This is the first one: on progress transition.

> +		ret = -ECANCELED;
> +	} else {
> +		imgld->progress = new_progress;
> +	}
> +	mutex_unlock(&imgld->lock);
> +	return ret;
> +}
> +
>  static void fpga_image_prog_complete(struct fpga_image_load *imgld)
>  {
>  	mutex_lock(&imgld->lock);
> @@ -79,8 +97,10 @@ static void fpga_image_do_load(struct work_struct *work)
>  		goto modput_exit;
>  	}
>  
> -	fpga_image_update_progress(imgld, FPGA_IMAGE_PROG_WRITING);
> -	while (imgld->remaining_size) {
> +	if (fpga_image_prog_transition(imgld, FPGA_IMAGE_PROG_WRITING))
> +		goto done;
> +
> +	while (imgld->remaining_size && !imgld->request_cancel) {

This is the second condition: when we finished a block write. But if the
low level driver accepts the whole block size, we cannot cancel in
between.

Actually the framework doesn't know when to successfully cancel an
update. It depends on the hardware.

So maybe the framework just calls cancel() immediately in IOCTL,
let the low level driver decides if it is feasible and how to cancel.

Thanks,
Yilun

>  		/*
>  		 * The write_blk() op has the option to use the blk_size
>  		 * value provided here, or to modify it to something more
> @@ -105,7 +125,9 @@ static void fpga_image_do_load(struct work_struct *work)
>  		cond_resched();
>  	}
>  
> -	fpga_image_update_progress(imgld, FPGA_IMAGE_PROG_PROGRAMMING);
> +	if (fpga_image_prog_transition(imgld, FPGA_IMAGE_PROG_PROGRAMMING))
> +		goto done;
> +
>  	ret = imgld->ops->poll_complete(imgld);
>  	if (ret != FPGA_IMAGE_ERR_NONE)
>  		fpga_image_dev_error(imgld, ret);
> @@ -178,8 +200,8 @@ static int fpga_image_load_ioctl_write(struct fpga_image_load *imgld,
>  	imgld->remaining_size = wb.size;
>  	imgld->err_code = FPGA_IMAGE_ERR_NONE;
>  	imgld->progress = FPGA_IMAGE_PROG_STARTING;
> +	imgld->request_cancel = false;
>  	queue_work(system_unbound_wq, &imgld->work);
> -
>  	return 0;
>  
>  exit_free:
> @@ -208,7 +230,7 @@ static long fpga_image_load_ioctl(struct file *filp, unsigned int cmd,
>  				  unsigned long arg)
>  {
>  	struct fpga_image_load *imgld = filp->private_data;
> -	int ret = -ENOTTY;
> +	int ret = 0;
>  
>  	mutex_lock(&imgld->lock);
>  
> @@ -219,6 +241,17 @@ static long fpga_image_load_ioctl(struct file *filp, unsigned int cmd,
>  	case FPGA_IMAGE_LOAD_STATUS:
>  		ret = fpga_image_load_ioctl_status(imgld, arg);
>  		break;
> +	case FPGA_IMAGE_LOAD_CANCEL:
> +		if (imgld->progress == FPGA_IMAGE_PROG_PROGRAMMING)
> +			ret = -EBUSY;
> +		else if (imgld->progress == FPGA_IMAGE_PROG_IDLE)
> +			ret = -ENODEV;
> +		else
> +			imgld->request_cancel = true;
> +		break;
> +	default:
> +		ret = -ENOTTY;
> +		break;
>  	}
>  
>  	mutex_unlock(&imgld->lock);
> @@ -249,6 +282,9 @@ static int fpga_image_load_release(struct inode *inode, struct file *filp)
>  		goto close_exit;
>  	}
>  
> +	if (imgld->progress != FPGA_IMAGE_PROG_PROGRAMMING)
> +		imgld->request_cancel = true;
> +
>  	mutex_unlock(&imgld->lock);
>  	flush_work(&imgld->work);
>  
> @@ -363,6 +399,9 @@ void fpga_image_load_unregister(struct fpga_image_load *imgld)
>  		goto unregister;
>  	}
>  
> +	if (imgld->progress != FPGA_IMAGE_PROG_PROGRAMMING)
> +		imgld->request_cancel = true;
> +
>  	mutex_unlock(&imgld->lock);
>  	flush_work(&imgld->work);
>  
> diff --git a/include/linux/fpga/fpga-image-load.h b/include/linux/fpga/fpga-image-load.h
> index 8b58365893fc..8ba39d3299d9 100644
> --- a/include/linux/fpga/fpga-image-load.h
> +++ b/include/linux/fpga/fpga-image-load.h
> @@ -53,6 +53,7 @@ struct fpga_image_load {
>  	u32 progress;
>  	u32 err_progress;		/* progress at time of error */
>  	u32 err_code;			/* image load error code */
> +	bool request_cancel;
>  	bool driver_unload;
>  	struct eventfd_ctx *finished;
>  	void *priv;
> diff --git a/include/uapi/linux/fpga-image-load.h b/include/uapi/linux/fpga-image-load.h
> index dc0c9f1d78b1..da8a7452c29a 100644
> --- a/include/uapi/linux/fpga-image-load.h
> +++ b/include/uapi/linux/fpga-image-load.h
> @@ -70,4 +70,6 @@ struct fpga_image_status {
>  
>  #define FPGA_IMAGE_LOAD_STATUS	_IOR(FPGA_IMAGE_LOAD_MAGIC, 1, struct fpga_image_status)
>  
> +#define FPGA_IMAGE_LOAD_CANCEL	_IO(FPGA_IMAGE_LOAD_MAGIC, 2)
> +
>  #endif /* _UAPI_LINUX_FPGA_IMAGE_LOAD_H */
> -- 
> 2.25.1