[PATCH RFC 1/4] Debugfs support for reading an array of u32-type integers

Srivatsa Vaddagiri
2010-07-26T06:14:03Z

Debugfs support for reading an array of u32-type integers. This is a rework of
what code already exists for Xen.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
---
arch/x86/xen/debugfs.c | 104 ----------------------------------------
arch/x86/xen/debugfs.h | 4 -
arch/x86/xen/mmu.c | 2
arch/x86/xen/multicalls.c | 6 +-
arch/x86/xen/spinlock.c | 6 +-
fs/debugfs/file.c | 117 ++++++++++++++++++++++++++++++++++++++++++++++
include/linux/debugfs.h | 11 ++++
7 files changed, 135 insertions(+), 115 deletions(-)

Index: current/arch/x86/xen/debugfs.c
===================================================================
--- current.orig/arch/x86/xen/debugfs.c
+++ current/arch/x86/xen/debugfs.c
@@ -18,107 +18,3 @@ struct dentry * __init xen_init_debugfs(

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,
-};
-
-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);
-}
Index: current/arch/x86/xen/debugfs.h
===================================================================
--- current.orig/arch/x86/xen/debugfs.h
+++ current/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 */
Index: current/arch/x86/xen/mmu.c
===================================================================
--- current.orig/arch/x86/xen/mmu.c
+++ current/arch/x86/xen/mmu.c
@@ -1983,7 +1983,7 @@ static int __init xen_mmu_debugfs(void)
debugfs_create_u32("mmu_update", 0444, d_mmu_debug, &mmu_stats.mmu_update);
debugfs_create_u32("mmu_update_extended", 0444, d_mmu_debug,
&mmu_stats.mmu_update_extended);
- xen_debugfs_create_u32_array("mmu_update_histo", 0444, d_mmu_debug,
+ debugfs_create_u32_array("mmu_update_histo", 0444, d_mmu_debug,
mmu_stats.mmu_update_histo, 20);

debugfs_create_u32("set_pte_at", 0444, d_mmu_debug, &mmu_stats.set_pte_at);
Index: current/arch/x86/xen/multicalls.c
===================================================================
--- current.orig/arch/x86/xen/multicalls.c
+++ current/arch/x86/xen/multicalls.c
@@ -269,11 +269,11 @@ static int __init xen_mc_debugfs(void)
debugfs_create_u32("hypercalls", 0444, d_mc_debug, &mc_stats.hypercalls);
debugfs_create_u32("arg_total", 0444, d_mc_debug, &mc_stats.arg_total);

- xen_debugfs_create_u32_array("batch_histo", 0444, d_mc_debug,
+ debugfs_create_u32_array("batch_histo", 0444, d_mc_debug,
mc_stats.histo, MC_BATCH);
- xen_debugfs_create_u32_array("hypercall_histo", 0444, d_mc_debug,
+ debugfs_create_u32_array("hypercall_histo", 0444, d_mc_debug,
mc_stats.histo_hypercalls, NHYPERCALLS);
- xen_debugfs_create_u32_array("flush_reasons", 0444, d_mc_debug,
+ debugfs_create_u32_array("flush_reasons", 0444, d_mc_debug,
mc_stats.flush, FL_N_REASONS);

return 0;
Index: current/arch/x86/xen/spinlock.c
===================================================================
--- current.orig/arch/x86/xen/spinlock.c
+++ current/arch/x86/xen/spinlock.c
@@ -423,11 +423,11 @@ static int __init xen_spinlock_debugfs(v
debugfs_create_u64("time_total", 0444, d_spin_debug,
&spinlock_stats.time_total);

- xen_debugfs_create_u32_array("histo_total", 0444, d_spin_debug,
+ debugfs_create_u32_array("histo_total", 0444, d_spin_debug,
spinlock_stats.histo_spin_total, HISTO_BUCKETS + 1);
- xen_debugfs_create_u32_array("histo_spinning", 0444, d_spin_debug,
+ debugfs_create_u32_array("histo_spinning", 0444, d_spin_debug,
spinlock_stats.histo_spin_spinning, HISTO_BUCKETS + 1);
- 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;
Index: current/fs/debugfs/file.c
===================================================================
--- current.orig/fs/debugfs/file.c
+++ current/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)
@@ -531,3 +532,119 @@ struct dentry *debugfs_create_blob(const
return debugfs_create_file(name, mode, parent, blob, &fops_blob);
}
EXPORT_SYMBOL_GPL(debugfs_create_blob);
+
+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) {
+ kfree(file->private_data);
+ 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,
+};
+
+/**
+ * debugfs_create_u32_array - create a debugfs file that is used to read an array of unsigned 32-bit values.
+ * @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: array of integers of type u32
+ * @elements: number of elements in the array
+ */
+struct dentry *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;
+
+ /* u32 array can't be written or executed! */
+ if (mode & (S_IWUGO | S_IXUGO))
+ return ERR_PTR(-EINVAL);
+
+ data->array = array;
+ data->elements = elements;
+
+ return debugfs_create_file(name, mode, parent, data, &u32_array_fops);
+}
Index: current/include/linux/debugfs.h
===================================================================
--- current.orig/include/linux/debugfs.h
+++ current/include/linux/debugfs.h
@@ -74,6 +74,10 @@ struct dentry *debugfs_create_blob(const
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, unsigned elements);
+
bool debugfs_initialized(void);

#else
@@ -188,6 +192,13 @@ static inline struct dentry *debugfs_cre
return ERR_PTR(-ENODEV);
}

+struct dentry *debugfs_create_u32_array(const char *name, mode_t mode,
+ struct dentry *parent,
+ u32 *array, unsigned elements)
+{
+ return ERR_PTR(-ENODEV);
+}
+
static inline bool debugfs_initialized(void)
{
return false;