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    SubjectRe: [Xen-devel] [PATCH RFC V3 1/4] debugfs: Add support to print u32 array in debugfs
    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
    >
    >
    > _______________________________________________
    > Xen-devel mailing list
    > Xen-devel@lists.xensource.com
    > http://lists.xensource.com/xen-devel


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