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 <sjenning@linux.vnet.ibm.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 44 insertions, 21 deletions

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index c5ca6ae5a30c..ff64bcd5b8fb 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -21,6 +21,7 @@
 #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)
@@ -403,6 +404,47 @@ struct dentry *debugfs_create_size_t(const char *name, umode_t mode,
 }
 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)
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index 63f2465807d4..d68b4ea7343c 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -79,6 +79,8 @@ struct dentry *debugfs_create_x64(const char *name, umode_t mode,
                                   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);
 
diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index c5c7a762b850..d7d501ea856d 100644
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -182,27 +182,6 @@ static struct dentry *debugfs_create_stacktrace_depth(
 
 #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)
 {