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

[Xu Yilun <yilun.xu@intel.com>]

On Fri, Sep 24, 2021 at 05:29:28PM -0700, Russ Weight wrote:
> 
> 
> On 9/24/21 7:53 AM, Xu Yilun wrote:
> > 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@intel.com>
> >> ---
> >> 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
> I'll fix it
> >> +EBUSY if it cannot be cancelled by software or ENODEV if there is no update
> >    -EBUSY					 -ENODEV
> 
> >From the userspace perspective, these are seen as positive errno numbers.
> I think this is OK as is? If not, I need to change it in other places as well.

I agree, just keep it.

> >
> >> +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.
> 
> Yes - I agree. This current implementation assumes too much about
> the low-level driver. I have some ideas to try in the next patchset.
> 
> Thanks,
> - Russ
> >
> > 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