debugfs: add get/set for atomic types

debugfs currently lack the ability to create attributes
that set/get atomic_t values.

This patch adds support for this through a new
debugfs_create_atomic_t() function.

Signed-off-by: Seth Jennings <[e-mail]>
Acked-by: Greg Kroah-Hartman <[e-mail]>
Acked-by: Mel Gorman <[e-mail]>
Acked-by: Rik van Riel <[e-mail]>
Acked-by: Konrad Rzeszutek Wilk <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

fs/debugfs/file.c

···
 #include <linux/debugfs.h>
 #include <linux/io.h>
 #include <linux/slab.h>
+#include <linux/atomic.h>
 
 static ssize_t default_read_file(struct file *file, char __user *buf,
 				 size_t count, loff_t *ppos)
···
 }
 EXPORT_SYMBOL_GPL(debugfs_create_size_t);
 
+static int debugfs_atomic_t_set(void *data, u64 val)
+{
+	atomic_set((atomic_t *)data, val);
+	return 0;
+}
+static int debugfs_atomic_t_get(void *data, u64 *val)
+{
+	*val = atomic_read((atomic_t *)data);
+	return 0;
+}
+DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
+			debugfs_atomic_t_set, "%lld\n");
+DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t_ro, debugfs_atomic_t_get, NULL, "%lld\n");
+DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t_wo, NULL, debugfs_atomic_t_set, "%lld\n");
+
+/**
+ * debugfs_create_atomic_t - create a debugfs file that is used to read and
+ * write an atomic_t value
+ * @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.
+ * @value: a pointer to the variable that the file should read to and write
+ *         from.
+ */
+struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
+				 struct dentry *parent, atomic_t *value)
+{
+	/* if there are no write bits set, make read only */
+	if (!(mode & S_IWUGO))
+		return debugfs_create_file(name, mode, parent, value,
+					&fops_atomic_t_ro);
+	/* if there are no read bits set, make write only */
+	if (!(mode & S_IRUGO))
+		return debugfs_create_file(name, mode, parent, value,
+					&fops_atomic_t_wo);
+
+	return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
+}
+EXPORT_SYMBOL_GPL(debugfs_create_atomic_t);
 
 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
 			      size_t count, loff_t *ppos)

include/linux/debugfs.h

···
 				  struct dentry *parent, u64 *value);
 struct dentry *debugfs_create_size_t(const char *name, umode_t mode,
 				     struct dentry *parent, size_t *value);
+struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
+				     struct dentry *parent, atomic_t *value);
 struct dentry *debugfs_create_bool(const char *name, umode_t mode,
 				  struct dentry *parent, u32 *value);
 

lib/fault-inject.c

···
 
 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 
-static int debugfs_atomic_t_set(void *data, u64 val)
-{
-	atomic_set((atomic_t *)data, val);
-	return 0;
-}
-
-static int debugfs_atomic_t_get(void *data, u64 *val)
-{
-	*val = atomic_read((atomic_t *)data);
-	return 0;
-}
-
-DEFINE_SIMPLE_ATTRIBUTE(fops_atomic_t, debugfs_atomic_t_get,
-			debugfs_atomic_t_set, "%lld\n");
-
-static struct dentry *debugfs_create_atomic_t(const char *name, umode_t mode,
-				struct dentry *parent, atomic_t *value)
-{
-	return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
-}
-
 struct dentry *fault_create_debugfs_attr(const char *name,
 			struct dentry *parent, struct fault_attr *attr)
 {