Re: [Xen-devel] [PATCH RFC V3 1/4] debugfs: Add support to print u32 array in debugfs

[Konrad Rzeszutek Wilk <konrad@darnok.org>]

On Wed, Nov 30, 2011 at 02:29:39PM +0530, Raghavendra K T wrote:
> Add debugfs support to print u32-arrays in debugfs. Move the code from Xen to debugfs
> to make the code common for other users as well.
> 
> Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
> Signed-off-by: Suzuki Poulose <suzuki@in.ibm.com>
> Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>

Looks good to me.
> ---
> diff --git a/arch/x86/xen/debugfs.c b/arch/x86/xen/debugfs.c
> index 7c0fedd..c8377fb 100644
> --- a/arch/x86/xen/debugfs.c
> +++ b/arch/x86/xen/debugfs.c
> @@ -19,107 +19,3 @@ struct dentry * __init xen_init_debugfs(void)
>  	return d_xen_debug;
>  }
>  
> -struct array_data
> -{
> -	void *array;
> -	unsigned elements;
> -};
> -
> -static int u32_array_open(struct inode *inode, struct file *file)
> -{
> -	file->private_data = NULL;
> -	return nonseekable_open(inode, file);
> -}
> -
> -static size_t format_array(char *buf, size_t bufsize, const char *fmt,
> -			   u32 *array, unsigned array_size)
> -{
> -	size_t ret = 0;
> -	unsigned i;
> -
> -	for(i = 0; i < array_size; i++) {
> -		size_t len;
> -
> -		len = snprintf(buf, bufsize, fmt, array[i]);
> -		len++;	/* ' ' or '\n' */
> -		ret += len;
> -
> -		if (buf) {
> -			buf += len;
> -			bufsize -= len;
> -			buf[-1] = (i == array_size-1) ? '\n' : ' ';
> -		}
> -	}
> -
> -	ret++;		/* \0 */
> -	if (buf)
> -		*buf = '\0';
> -
> -	return ret;
> -}
> -
> -static char *format_array_alloc(const char *fmt, u32 *array, unsigned array_size)
> -{
> -	size_t len = format_array(NULL, 0, fmt, array, array_size);
> -	char *ret;
> -
> -	ret = kmalloc(len, GFP_KERNEL);
> -	if (ret == NULL)
> -		return NULL;
> -
> -	format_array(ret, len, fmt, array, array_size);
> -	return ret;
> -}
> -
> -static ssize_t u32_array_read(struct file *file, char __user *buf, size_t len,
> -			      loff_t *ppos)
> -{
> -	struct inode *inode = file->f_path.dentry->d_inode;
> -	struct array_data *data = inode->i_private;
> -	size_t size;
> -
> -	if (*ppos == 0) {
> -		if (file->private_data) {
> -			kfree(file->private_data);
> -			file->private_data = NULL;
> -		}
> -
> -		file->private_data = format_array_alloc("%u", data->array, data->elements);
> -	}
> -
> -	size = 0;
> -	if (file->private_data)
> -		size = strlen(file->private_data);
> -
> -	return simple_read_from_buffer(buf, len, ppos, file->private_data, size);
> -}
> -
> -static int xen_array_release(struct inode *inode, struct file *file)
> -{
> -	kfree(file->private_data);
> -
> -	return 0;
> -}
> -
> -static const struct file_operations u32_array_fops = {
> -	.owner	= THIS_MODULE,
> -	.open	= u32_array_open,
> -	.release= xen_array_release,
> -	.read	= u32_array_read,
> -	.llseek = no_llseek,
> -};
> -
> -struct dentry *xen_debugfs_create_u32_array(const char *name, mode_t mode,
> -					    struct dentry *parent,
> -					    u32 *array, unsigned elements)
> -{
> -	struct array_data *data = kmalloc(sizeof(*data), GFP_KERNEL);
> -
> -	if (data == NULL)
> -		return NULL;
> -
> -	data->array = array;
> -	data->elements = elements;
> -
> -	return debugfs_create_file(name, mode, parent, data, &u32_array_fops);
> -}
> diff --git a/arch/x86/xen/debugfs.h b/arch/x86/xen/debugfs.h
> index e281320..12ebf33 100644
> --- a/arch/x86/xen/debugfs.h
> +++ b/arch/x86/xen/debugfs.h
> @@ -3,8 +3,4 @@
>  
>  struct dentry * __init xen_init_debugfs(void);
>  
> -struct dentry *xen_debugfs_create_u32_array(const char *name, mode_t mode,
> -					    struct dentry *parent,
> -					    u32 *array, unsigned elements);
> -
>  #endif /* _XEN_DEBUGFS_H */
> diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
> index fc506e6..14a8961 100644
> --- a/arch/x86/xen/spinlock.c
> +++ b/arch/x86/xen/spinlock.c
> @@ -286,7 +286,7 @@ static int __init xen_spinlock_debugfs(void)
>  	debugfs_create_u64("time_blocked", 0444, d_spin_debug,
>  			   &spinlock_stats.time_blocked);
>  
> -	xen_debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
> +	debugfs_create_u32_array("histo_blocked", 0444, d_spin_debug,
>  				     spinlock_stats.histo_spin_blocked, HISTO_BUCKETS + 1);
>  
>  	return 0;
> diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
> index 90f7657..df44ccf 100644
> --- a/fs/debugfs/file.c
> +++ b/fs/debugfs/file.c
> @@ -18,6 +18,7 @@
>  #include <linux/pagemap.h>
>  #include <linux/namei.h>
>  #include <linux/debugfs.h>
> +#include <linux/slab.h>
>  
>  static ssize_t default_read_file(struct file *file, char __user *buf,
>  				 size_t count, loff_t *ppos)
> @@ -525,3 +526,130 @@ struct dentry *debugfs_create_blob(const char *name, mode_t mode,
>  	return debugfs_create_file(name, mode, parent, blob, &fops_blob);
>  }
>  EXPORT_SYMBOL_GPL(debugfs_create_blob);
> +
> +struct array_data {
> +	void *array;
> +	u32 elements;
> +};
> +
> +static int u32_array_open(struct inode *inode, struct file *file)
> +{
> +	file->private_data = NULL;
> +	return nonseekable_open(inode, file);
> +}
> +
> +static size_t format_array(char *buf, size_t bufsize, const char *fmt,
> +			   u32 *array, u32 array_size)
> +{
> +	size_t ret = 0;
> +	u32 i;
> +
> +	for (i = 0; i < array_size; i++) {
> +		size_t len;
> +
> +		len = snprintf(buf, bufsize, fmt, array[i]);
> +		len++;	/* ' ' or '\n' */
> +		ret += len;
> +
> +		if (buf) {
> +			buf += len;
> +			bufsize -= len;
> +			buf[-1] = (i == array_size-1) ? '\n' : ' ';
> +		}
> +	}
> +
> +	ret++;		/* \0 */
> +	if (buf)
> +		*buf = '\0';
> +
> +	return ret;
> +}
> +
> +static char *format_array_alloc(const char *fmt, u32 *array,
> +						u32 array_size)
> +{
> +	size_t len = format_array(NULL, 0, fmt, array, array_size);
> +	char *ret;
> +
> +	ret = kmalloc(len, GFP_KERNEL);
> +	if (ret == NULL)
> +		return NULL;
> +
> +	format_array(ret, len, fmt, array, array_size);
> +	return ret;
> +}
> +
> +static ssize_t u32_array_read(struct file *file, char __user *buf, size_t len,
> +			      loff_t *ppos)
> +{
> +	struct inode *inode = file->f_path.dentry->d_inode;
> +	struct array_data *data = inode->i_private;
> +	size_t size;
> +
> +	if (*ppos == 0) {
> +		if (file->private_data) {
> +			kfree(file->private_data);
> +			file->private_data = NULL;
> +		}
> +
> +		file->private_data = format_array_alloc("%u", data->array,
> +							      data->elements);
> +	}
> +
> +	size = 0;
> +	if (file->private_data)
> +		size = strlen(file->private_data);
> +
> +	return simple_read_from_buffer(buf, len, ppos,
> +					file->private_data, size);
> +}
> +
> +static int u32_array_release(struct inode *inode, struct file *file)
> +{
> +	kfree(file->private_data);
> +
> +	return 0;
> +}
> +
> +static const struct file_operations u32_array_fops = {
> +	.owner	 = THIS_MODULE,
> +	.open	 = u32_array_open,
> +	.release = u32_array_release,
> +	.read	 = u32_array_read,
> +	.llseek  = no_llseek,
> +};
> +
> +/**
> + * debugfs_create_u32_array - create a debugfs file that is used to read u32
> + * array.
> + * @name: a pointer to a string containing the name of the file to create.
> + * @mode: the permission that the file should have.
> + * @parent: a pointer to the parent dentry for this file.  This should be a
> + *          directory dentry if set.  If this parameter is %NULL, then the
> + *          file will be created in the root of the debugfs filesystem.
> + * @array: u32 array that provides data.
> + * @elements: total number of elements in the array.
> + *
> + * This function creates a file in debugfs with the given name that exports
> + * @array as data. If the @mode variable is so set it can be read from.
> + * Writing is not supported. Seek within the file is also not supported.
> + * Once array is created its size can not be changed.
> + *
> + * The function returns a pointer to dentry on success. If debugfs is not
> + * enabled in the kernel, the value -%ENODEV will be returned.
> + */
> +struct dentry *debugfs_create_u32_array(const char *name, mode_t mode,
> +					    struct dentry *parent,
> +					    u32 *array, u32 elements)
> +{
> +	struct array_data *data = kmalloc(sizeof(*data), GFP_KERNEL);
> +
> +	if (data == NULL)
> +		return NULL;
> +
> +	data->array = array;
> +	data->elements = elements;
> +
> +	return debugfs_create_file(name, mode, parent, data, &u32_array_fops);
> +}
> +EXPORT_SYMBOL_GPL(debugfs_create_u32_array);
> diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
> index e7d9b20..253e2fb 100644
> --- a/include/linux/debugfs.h
> +++ b/include/linux/debugfs.h
> @@ -74,6 +74,10 @@ struct dentry *debugfs_create_blob(const char *name, mode_t mode,
>  				  struct dentry *parent,
>  				  struct debugfs_blob_wrapper *blob);
>  
> +struct dentry *debugfs_create_u32_array(const char *name, mode_t mode,
> +					struct dentry *parent,
> +					u32 *array, u32 elements);
> +
>  bool debugfs_initialized(void);
>  
>  #else
> @@ -193,6 +197,13 @@ static inline bool debugfs_initialized(void)
>  	return false;
>  }
>  
> +struct dentry *debugfs_create_u32_array(const char *name, mode_t mode,
> +					struct dentry *parent,
> +					u32 *array, u32 elements)
> +{
> +	return ERR_PTR(-ENODEV);
> +}
> +
>  #endif
>  
>  #endif
> 
> 
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