Re: [PATCH v15 6/6] fpga: image-load: enable cancel of image upload

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

On Sat, Sep 11, 2021 at 06:13:08AM -0700, Tom Rix wrote:
> 
> On 9/10/21 4:38 PM, Russ Weight wrote:
> > 
> > On 9/10/21 7:55 AM, Xu Yilun wrote:
> > > On Wed, Sep 08, 2021 at 07:18:46PM -0700, Russ Weight wrote:
> > > > Extend the FPGA Image Load class driver 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>
> > > > ---
> > > > 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         | 45 +++++++++++++++++++++++---
> > > >   include/linux/fpga/fpga-image-load.h   |  1 +
> > > >   include/uapi/linux/fpga-image-load.h   |  1 +
> > > >   4 files changed, 49 insertions(+), 4 deletions(-)
> > > > 
> > > > diff --git a/Documentation/fpga/fpga-image-load.rst b/Documentation/fpga/fpga-image-load.rst
> > > > index 3d5eb51223e3..763e7833a6ea 100644
> > > > --- a/Documentation/fpga/fpga-image-load.rst
> > > > +++ b/Documentation/fpga/fpga-image-load.rst
> > > > @@ -37,3 +37,9 @@ 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
> > > > +EBUSY if it cannot be cancelled by software or ENODEV if there is no update
> > > > +in progress.
> > > > diff --git a/drivers/fpga/fpga-image-load.c b/drivers/fpga/fpga-image-load.c
> > > > index 6ec0a39f07b3..c32e4b1ea35a 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,
> > > >   	imgld->lops->cancel(imgld);
> > > >   }
> > > > +static int fpga_image_prog_transition(struct fpga_image_load *imgld,
> > > > +				      enum fpga_image_prog 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->lops->cancel(imgld);
> > > > +		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);
> > > > @@ -77,8 +95,10 @@ 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) {
> > > >   		ret = imgld->lops->write_blk(imgld, offset);
> > > >   		if (ret != FPGA_IMAGE_ERR_NONE) {
> > > >   			fpga_image_dev_error(imgld, ret);
> > > > @@ -88,7 +108,9 @@ static void fpga_image_do_load(struct work_struct *work)
> > > >   		offset = size - imgld->remaining_size;
> > > >   	}
> > > > -	fpga_image_update_progress(imgld, FPGA_IMAGE_PROG_PROGRAMMING);
> > > > +	if (fpga_image_prog_transition(imgld, FPGA_IMAGE_PROG_PROGRAMMING))
> > > > +		goto done;
> > > > +
> > > >   	ret = imgld->lops->poll_complete(imgld);
> > > >   	if (ret != FPGA_IMAGE_ERR_NONE)
> > > >   		fpga_image_dev_error(imgld, ret);
> > > > @@ -159,6 +181,7 @@ 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;
> > > >   	reinit_completion(&imgld->update_done);
> > > >   	schedule_work(&imgld->work);
> > > >   	return 0;
> > > > @@ -189,7 +212,7 @@ 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);
> > > > @@ -200,6 +223,17 @@ 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);
> > > > @@ -374,6 +408,9 @@ void fpga_image_load_unregister(struct fpga_image_load *imgld)
> > > >   		goto unregister;
> > > >   	}
> > > > +	if (imgld->progress != FPGA_IMAGE_PROG_PROGRAMMING)
> > > > +		imgld->request_cancel = true;
> > > > +
> > > Why we cancel the programing rather than waiting for programing done?
> > This isn't new - it is the way the security manager was implemented.
> > 
> > Updates can take up to 40 minutes for the N3000. If a person tries
> > to unload the driver modules, should we hang for 40 minutes? Or should
> > we try to cancel the update and allow the module to be unloaded?
> > I think it is reasonable to cancel the update (if possible) under these
> > circumstances. What do you think?
> 
> I do not think stalling a shutdown for 40 minutes is good.
> 
> Is there a chance that cancelling would brick the card?

If the cancel cannot be possible, may be we could wait. Or the user
image would be corrupted with a simple poweroff command.

Thanks,
Yilun

> 
> After restarting, can the hw detect an interrupted update ?
> 
> Tom
> 
> > 
> > - Russ
> > 
> > > Thanks,
> > > Yilun
> > > 
> > > >   	mutex_unlock(&imgld->lock);
> > > >   	wait_for_completion(&imgld->update_done);
> > > > diff --git a/include/linux/fpga/fpga-image-load.h b/include/linux/fpga/fpga-image-load.h
> > > > index 68f3105b51d2..4e51b9fd1724 100644
> > > > --- a/include/linux/fpga/fpga-image-load.h
> > > > +++ b/include/linux/fpga/fpga-image-load.h
> > > > @@ -52,6 +52,7 @@ struct fpga_image_load {
> > > >   	enum fpga_image_prog progress;
> > > >   	enum fpga_image_prog err_progress;	/* progress at time of failure */
> > > >   	enum fpga_image_err 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 6a995bcc0fb7..8d0dfa1f9b77 100644
> > > > --- a/include/uapi/linux/fpga-image-load.h
> > > > +++ b/include/uapi/linux/fpga-image-load.h
> > > > @@ -39,6 +39,7 @@ enum fpga_image_err {
> > > >   #define FPGA_IMAGE_LOAD_WRITE	_IOW(FPGA_IMAGE_LOAD_MAGIC, 0, struct fpga_image_write)
> > > >   #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)
> > > >   /**
> > > >    * FPGA_IMAGE_LOAD_WRITE - _IOW(FPGA_IMAGE_LOAD_MAGIC, 0,
> > > > -- 
> > > > 2.25.1