UBI: use debugfs for the extra checks knobs

This patch introduces debugfs support to UBI. All the UBI stuff is kept in the
"ubi" debugfs directory, which contains per-UBI device "ubi/ubiX"
sub-directories, containing debugging files. This file also creates
"ubi/ubiX/chk_gen" and "ubi/ubiX/chk_io" knobs for switching general and I/O
extra checks on and off. And it removes the 'debug_chks' UBI module parameters.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 227 insertions, 4 deletions

diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
index 2224cbe41ddf..dce1227929f1 100644
--- a/drivers/mtd/ubi/debug.c
+++ b/drivers/mtd/ubi/debug.c
@@ -27,16 +27,15 @@
 #ifdef CONFIG_MTD_UBI_DEBUG
 
 #include "ubi.h"
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 
-unsigned int ubi_chk_flags;
 unsigned int ubi_tst_flags;
 
-module_param_named(debug_chks, ubi_chk_flags, uint, S_IRUGO | S_IWUSR);
-module_param_named(debug_tsts, ubi_chk_flags, uint, S_IRUGO | S_IWUSR);
+module_param_named(debug_tsts, ubi_tst_flags, uint, S_IRUGO | S_IWUSR);
 
-MODULE_PARM_DESC(debug_chks, "Debug check flags");
 MODULE_PARM_DESC(debug_tsts, "Debug special test flags");
 
 /**
@@ -239,4 +238,228 @@ out:
 	return;
 }
 
+/**
+ * ubi_debugging_init_dev - initialize debugging for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * This function initializes debugging-related data for UBI device @ubi.
+ * Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+int ubi_debugging_init_dev(struct ubi_device *ubi)
+{
+	ubi->dbg = kzalloc(sizeof(struct ubi_debug_info), GFP_KERNEL);
+	if (!ubi->dbg)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * ubi_debugging_exit_dev - free debugging data for an UBI device.
+ * @ubi: UBI device description object
+ */
+void ubi_debugging_exit_dev(struct ubi_device *ubi)
+{
+	kfree(ubi->dbg);
+}
+
+/*
+ * Root directory for UBI stuff in debugfs. Contains sub-directories which
+ * contain the stuff specific to particular UBI devices.
+ */
+static struct dentry *dfs_rootdir;
+
+/**
+ * ubi_debugfs_init - create UBI debugfs directory.
+ *
+ * Create UBI debugfs directory. Returns zero in case of success and a negative
+ * error code in case of failure.
+ */
+int ubi_debugfs_init(void)
+{
+	dfs_rootdir = debugfs_create_dir("ubi", NULL);
+	if (IS_ERR_OR_NULL(dfs_rootdir)) {
+		int err = dfs_rootdir ? -ENODEV : PTR_ERR(dfs_rootdir);
+
+		ubi_err("cannot create \"ubi\" debugfs directory, error %d\n",
+			err);
+		return err;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_debugfs_exit - remove UBI debugfs directory.
+ */
+void ubi_debugfs_exit(void)
+{
+	debugfs_remove(dfs_rootdir);
+}
+
+/* Read an UBI debugfs file */
+static ssize_t dfs_file_read(struct file *file, char __user *user_buf,
+			     size_t count, loff_t *ppos)
+{
+	unsigned long ubi_num = (unsigned long)file->private_data;
+	struct dentry *dent = file->f_path.dentry;
+	struct ubi_device *ubi;
+	struct ubi_debug_info *d;
+	char buf[3];
+	int val;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+	d = ubi->dbg;
+
+	if (dent == d->dfs_chk_gen)
+		val = d->chk_gen;
+	else if (dent == d->dfs_chk_io)
+		val = d->chk_io;
+	else {
+		count = -EINVAL;
+		goto out;
+	}
+
+	if (val)
+		buf[0] = '1';
+	else
+		buf[0] = '0';
+	buf[1] = '\n';
+	buf[2] = 0x00;
+
+	count = simple_read_from_buffer(user_buf, count, ppos, buf, 2);
+
+out:
+	ubi_put_device(ubi);
+	return count;
+}
+
+/* Write an UBI debugfs file */
+static ssize_t dfs_file_write(struct file *file, const char __user *user_buf,
+			      size_t count, loff_t *ppos)
+{
+	unsigned long ubi_num = (unsigned long)file->private_data;
+	struct dentry *dent = file->f_path.dentry;
+	struct ubi_device *ubi;
+	struct ubi_debug_info *d;
+	size_t buf_size;
+	char buf[8];
+	int val;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+	d = ubi->dbg;
+
+	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
+	if (copy_from_user(buf, user_buf, buf_size)) {
+		count = -EFAULT;
+		goto out;
+	}
+
+	if (buf[0] == '1')
+		val = 1;
+	else if (buf[0] == '0')
+		val = 0;
+	else {
+		count = -EINVAL;
+		goto out;
+	}
+
+	if (dent == d->dfs_chk_gen)
+		d->chk_gen = val;
+	else if (dent == d->dfs_chk_io)
+		d->chk_io = val;
+	else
+		count = -EINVAL;
+
+out:
+	ubi_put_device(ubi);
+	return count;
+}
+
+static int default_open(struct inode *inode, struct file *file)
+{
+	if (inode->i_private)
+		file->private_data = inode->i_private;
+
+	return 0;
+}
+
+/* File operations for all UBI debugfs files */
+static const struct file_operations dfs_fops = {
+	.read   = dfs_file_read,
+	.write  = dfs_file_write,
+	.open   = default_open,
+	.llseek = no_llseek,
+	.owner  = THIS_MODULE,
+};
+
+/**
+ * ubi_debugfs_init_dev - initialize debugfs for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * This function creates all debugfs files for UBI device @ubi. Returns zero in
+ * case of success and a negative error code in case of failure.
+ */
+int ubi_debugfs_init_dev(struct ubi_device *ubi)
+{
+	int err, n;
+	unsigned long ubi_num = ubi->ubi_num;
+	const char *fname;
+	struct dentry *dent;
+	struct ubi_debug_info *d = ubi->dbg;
+
+	n = snprintf(d->dfs_dir_name, UBI_DFS_DIR_LEN + 1, UBI_DFS_DIR_NAME,
+		     ubi->ubi_num);
+	if (n == UBI_DFS_DIR_LEN) {
+		/* The array size is too small */
+		fname = UBI_DFS_DIR_NAME;
+		dent = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+	fname = d->dfs_dir_name;
+	dent = debugfs_create_dir(fname, dfs_rootdir);
+	if (IS_ERR_OR_NULL(dent))
+		goto out;
+	d->dfs_dir = dent;
+
+	fname = "chk_gen";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_gen = dent;
+
+	fname = "chk_io";
+	dent = debugfs_create_file(fname, S_IWUSR, d->dfs_dir, (void *)ubi_num,
+				   &dfs_fops);
+	if (IS_ERR_OR_NULL(dent))
+		goto out_remove;
+	d->dfs_chk_io = dent;
+
+	return 0;
+
+out_remove:
+	debugfs_remove_recursive(d->dfs_dir);
+out:
+	err = dent ? PTR_ERR(dent) : -ENODEV;
+	ubi_err("cannot create \"%s\" debugfs file or directory, error %d\n",
+		fname, err);
+	return err;
+}
+
+/**
+ * dbg_debug_exit_dev - free all debugfs files corresponding to device @ubi
+ * @ubi: UBI device description object
+ */
+void ubi_debugfs_exit_dev(struct ubi_device *ubi)
+{
+	debugfs_remove_recursive(ubi->dbg->dfs_dir);
+}
+
 #endif /* CONFIG_MTD_UBI_DEBUG */