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Message-ID: <Y1fd+1CrlCBYCoz0@kroah.com>
Date: Tue, 25 Oct 2022 15:00:43 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Kai Ye <yekai13@...wei.com>
Cc: linux-accelerators@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
linuxarm@...wei.com, zhangfei.gao@...aro.org,
wangzhou1@...ilicon.com
Subject: Re: [PATCH v9 1/3] uacce: supports device isolation feature
On Tue, Oct 25, 2022 at 12:39:29PM +0000, Kai Ye wrote:
> UACCE adds the hardware error isolation API. Users can configure
> the isolation frequency by this sysfs node. UACCE reports the device
> isolate state to the user space. If the AER error frequency exceeds
> the set value in one hour, the device will be isolated.
>
You are trying to "reach across" to different types of devices here,
why? That feels backwards. Why isn't the device that needs to use this
api just create a child class device of this type?
> Signed-off-by: Kai Ye <yekai13@...wei.com>
> ---
> drivers/misc/uacce/uacce.c | 145 +++++++++++++++++++++++++++++++++++++
> include/linux/uacce.h | 43 ++++++++++-
> 2 files changed, 187 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index b70a013139c7..f293fcdcf44f 100644
> --- a/drivers/misc/uacce/uacce.c
> +++ b/drivers/misc/uacce/uacce.c
> @@ -7,10 +7,100 @@
> #include <linux/slab.h>
> #include <linux/uacce.h>
>
> +#define MAX_ERR_ISOLATE_COUNT 65535
> +
> static struct class *uacce_class;
> static dev_t uacce_devt;
> static DEFINE_XARRAY_ALLOC(uacce_xa);
>
> +static int cdev_get(struct device *dev, void *data)
That's a very odd function, considering it does not "get" anything.
And it does not work on cdev structures.
> +{
> + struct uacce_device *uacce;
> + struct device **t_dev = data;
Why are you having to cast this? Why not make it a real pointer?
> +
> + uacce = container_of(dev, struct uacce_device, dev);
> + if (uacce->parent == *t_dev) {
> + *t_dev = dev;
> + return 1;
bool?
And what happened to the reference count here?
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * dev_to_uacce - Get structure uacce device from its parent device
> + * @dev the device
> + */
> +struct uacce_device *dev_to_uacce(struct device *dev)
> +{
> + struct device **tdev = &dev;
> + int ret;
> +
> + ret = class_for_each_device(uacce_class, NULL, tdev, cdev_get);
Ah, you use it here.
No, sorry, you can not just walk all devices in the tree and assume this
will work.
Why do you not already know the device already?
> + if (ret) {
> + dev = *tdev;
> + return container_of(dev, struct uacce_device, dev);
> + }
> + return NULL;
> +}
> +EXPORT_SYMBOL_GPL(dev_to_uacce);
Where is the reference counting here?
And again, horrible global function name :(
> +
> +/**
> + * uacce_hw_err_isolate - Try to set the isolation status of the uacce device
> + * according to user's configuration of isolation strategy.
> + * @uacce the uacce device
> + */
> +int uacce_hw_err_isolate(struct uacce_device *uacce)
> +{
> + struct uacce_hw_err *err, *tmp, *hw_err;
> + struct uacce_err_isolate *isolate_ctx;
> + u32 count = 0;
> +
> + if (!uacce)
> + return -EINVAL;
How can this happen?
> +
> + isolate_ctx = uacce->isolate_ctx;
> +
> +#define SECONDS_PER_HOUR 3600
We don't already have this in a header file?
> +
> + /* All the hw errs are processed by PF driver */
> + if (uacce->is_vf || isolate_ctx->is_isolate ||
> + !isolate_ctx->hw_err_isolate_hz)
> + return 0;
> +
> + hw_err = kzalloc(sizeof(*hw_err), GFP_KERNEL);
> + if (!hw_err)
> + return -ENOMEM;
> +
> + hw_err->timestamp = jiffies;
> + list_for_each_entry_safe(err, tmp, &isolate_ctx->hw_errs, list) {
> + if ((hw_err->timestamp - err->timestamp) / HZ >
> + SECONDS_PER_HOUR) {
> + list_del(&err->list);
> + kfree(err);
> + } else {
> + count++;
> + }
> + }
> + list_add(&hw_err->list, &isolate_ctx->hw_errs);
> +
> + if (count >= isolate_ctx->hw_err_isolate_hz)
> + isolate_ctx->is_isolate = true;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(uacce_hw_err_isolate);
> +
> +static void uacce_hw_err_destroy(struct uacce_device *uacce)
> +{
> + struct uacce_hw_err *err, *tmp;
> +
> + list_for_each_entry_safe(err, tmp, &uacce->isolate_data.hw_errs, list) {
> + list_del(&err->list);
> + kfree(err);
No reference counting at all?
> + }
> +}
> +
> /*
> * If the parent driver or the device disappears, the queue state is invalid and
> * ops are not usable anymore.
> @@ -363,12 +453,59 @@ static ssize_t region_dus_size_show(struct device *dev,
> uacce->qf_pg_num[UACCE_QFRT_DUS] << PAGE_SHIFT);
> }
>
> +static ssize_t isolate_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct uacce_device *uacce = to_uacce_device(dev);
> + int ret = UACCE_DEV_NORMAL;
> +
> + if (uacce->isolate_ctx->is_isolate)
> + ret = UACCE_DEV_ISOLATE;
> +
> + return sysfs_emit(buf, "%d\n", ret);
> +}
> +
> +static ssize_t isolate_strategy_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct uacce_device *uacce = to_uacce_device(dev);
> +
> + return sysfs_emit(buf, "%u\n", uacce->isolate_ctx->hw_err_isolate_hz);
> +}
> +
> +static ssize_t isolate_strategy_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct uacce_device *uacce = to_uacce_device(dev);
> + unsigned long val;
> +
> + /* must be set by PF */
> + if (uacce->is_vf)
> + return -EPERM;
> +
> + if (kstrtoul(buf, 0, &val) < 0)
> + return -EINVAL;
> +
> + if (val > MAX_ERR_ISOLATE_COUNT)
> + return -EINVAL;
> +
> + uacce->isolate_ctx->hw_err_isolate_hz = val;
> +
> + /* After the policy is updated, need to reset the hardware err list */
> + uacce_hw_err_destroy(uacce);
> +
> + return count;
> +}
> +
> static DEVICE_ATTR_RO(api);
> static DEVICE_ATTR_RO(flags);
> static DEVICE_ATTR_RO(available_instances);
> static DEVICE_ATTR_RO(algorithms);
> static DEVICE_ATTR_RO(region_mmio_size);
> static DEVICE_ATTR_RO(region_dus_size);
> +static DEVICE_ATTR_RO(isolate);
> +static DEVICE_ATTR_RW(isolate_strategy);
No documentation for these new sysfs files?
thanks,
greg k-h
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