[Xen-devel] [PATCH RFC V4 1/5] debugfs: Add support to print u32 array in debugfs

[Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>]

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@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Suzuki Poulose <suzuki@xxxxxxxxxx>
Signed-off-by: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
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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