netdev - Re: [patch net-next v2 1/2] netdevsim: implement support for devlink region and snapshots

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Date:   Tue, 13 Aug 2019 15:08:29 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, mlxsw@...lanox.com
Subject: Re: [patch net-next v2 1/2] netdevsim: implement support for
 devlink region and snapshots

On Tue, 13 Aug 2019 16:48:42 +0200, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@...lanox.com>
> 
> Implement dummy region of size 32K and allow user to create snapshots
> or random data using debugfs file trigger.
> 
> Signed-off-by: Jiri Pirko <jiri@...lanox.com>

Hmm.. did you send the right version?

> diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
> index 127aef85dc99..8485dd805f7c 100644
> --- a/drivers/net/netdevsim/dev.c
> +++ b/drivers/net/netdevsim/dev.c
> @@ -27,6 +27,41 @@
>  
>  static struct dentry *nsim_dev_ddir;
>  
> +#define NSIM_DEV_DUMMY_REGION_SIZE (1024 * 32)
> +
> +static ssize_t nsim_dev_take_snapshot_write(struct file *file,
> +					    const char __user *data,
> +					    size_t count, loff_t *ppos)
> +{
> +	struct nsim_dev *nsim_dev = file->private_data;
> +	void *dummy_data;
> +	u32 id;
> +	int err;
> +
> +	dummy_data = kmalloc(NSIM_DEV_DUMMY_REGION_SIZE, GFP_KERNEL);
> +	if (!dummy_data) {
> +		pr_err("Failed to allocate memory for region snapshot\n");

not needed, without __GFP_NOWARN there will be a huge OOM splat, anyway.

> +		goto out;

		return -ENOMEM;

> +	}
> +
> +	get_random_bytes(dummy_data, NSIM_DEV_DUMMY_REGION_SIZE);
> +
> +	id = devlink_region_shapshot_id_get(priv_to_devlink(nsim_dev));
> +	err = devlink_region_snapshot_create(nsim_dev->dummy_region,
> +					     dummy_data, id, kfree);
> +	if (err)
> +		pr_err("Failed to create region snapshot\n");

		return err;
	}

> +
> +out:
> +	return count;
> +}
> +
> +static const struct file_operations nsim_dev_take_snapshot_fops = {
> +	.open = simple_open,
> +	.write = nsim_dev_take_snapshot_write,
> +	.llseek = generic_file_llseek,
> +};
> +
>  static int nsim_dev_debugfs_init(struct nsim_dev *nsim_dev)
>  {
>  	char dev_ddir_name[16];
> @@ -44,6 +79,8 @@ static int nsim_dev_debugfs_init(struct nsim_dev *nsim_dev)
>  			   &nsim_dev->max_macs);
>  	debugfs_create_bool("test1", 0600, nsim_dev->ddir,
>  			    &nsim_dev->test1);
> +	debugfs_create_file("take_snapshot", 0200, nsim_dev->ddir, nsim_dev,
> +			    &nsim_dev_take_snapshot_fops);
>  	return 0;
>  }
>  
> @@ -248,6 +285,26 @@ static void nsim_devlink_param_load_driverinit_values(struct devlink *devlink)
>  		nsim_dev->test1 = saved_value.vbool;
>  }
>  
> +#define NSIM_DEV_DUMMY_REGION_SNAPSHOT_MAX 16
> +
> +static int nsim_dev_dummy_region_init(struct nsim_dev *nsim_dev,
> +				      struct devlink *devlink)
> +{
> +	nsim_dev->dummy_region =
> +		devlink_region_create(devlink, "dummy",
> +				      NSIM_DEV_DUMMY_REGION_SNAPSHOT_MAX,
> +				      NSIM_DEV_DUMMY_REGION_SIZE);
> +	if (IS_ERR(nsim_dev->dummy_region))
> +		return PTR_ERR(nsim_dev->dummy_region);
> +
> +	return 0;

	return PTR_ERR_OR_ZERO(nsim_dev->dummy_region);

> +}