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Date: Fri, 24 Sep 2021 17:29:28 -0700
From: Russ Weight <russell.h.weight@...el.com>
To: Xu Yilun <yilun.xu@...el.com>
CC: <mdf@...nel.org>, <linux-fpga@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <trix@...hat.com>,
<lgoncalv@...hat.com>, <hao.wu@...el.com>,
<matthew.gerlach@...el.com>
Subject: Re: [PATCH v16 5/5] fpga: image-load: enable cancel of image upload
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@...el.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.
>
>> +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
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