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>

drivers/mtd/ubi/build.c

@@ -953,10 +953,14 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
 	if (!ubi->peb_buf2)
 		goto out_free;
 
+	err = ubi_debugging_init_dev(ubi);
+	if (err)
+		goto out_free;
+
 	err = attach_by_scanning(ubi);
 	if (err) {
 		dbg_err("failed to attach by scanning, error %d", err);
-		goto out_free;
+		goto out_debugging;
 	}
 
 	if (ubi->autoresize_vol_id != -1) {
@@ -969,12 +973,16 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
 	if (err)
 		goto out_detach;
 
+	err = ubi_debugfs_init_dev(ubi);
+	if (err)
+		goto out_uif;
+
 	ubi->bgt_thread = kthread_create(ubi_thread, ubi, ubi->bgt_name);
 	if (IS_ERR(ubi->bgt_thread)) {
 		err = PTR_ERR(ubi->bgt_thread);
 		ubi_err("cannot spawn \"%s\", error %d", ubi->bgt_name,
 			err);
-		goto out_uif;
+		goto out_debugfs;
 	}
 
 	ubi_msg("attached mtd%d to ubi%d", mtd->index, ubi_num);
@@ -1008,12 +1016,16 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
 	ubi_notify_all(ubi, UBI_VOLUME_ADDED, NULL);
 	return ubi_num;
 
+out_debugfs:
+	ubi_debugfs_exit_dev(ubi);
 out_uif:
 	uif_close(ubi);
 out_detach:
 	ubi_wl_close(ubi);
 	free_internal_volumes(ubi);
 	vfree(ubi->vtbl);
+out_debugging:
+	ubi_debugging_exit_dev(ubi);
 out_free:
 	vfree(ubi->peb_buf1);
 	vfree(ubi->peb_buf2);
@@ -1080,11 +1092,13 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway)
 	 */
 	get_device(&ubi->dev);
 
+	ubi_debugfs_exit_dev(ubi);
 	uif_close(ubi);
 	ubi_wl_close(ubi);
 	free_internal_volumes(ubi);
 	vfree(ubi->vtbl);
 	put_mtd_device(ubi->mtd);
+	ubi_debugging_exit_dev(ubi);
 	vfree(ubi->peb_buf1);
 	vfree(ubi->peb_buf2);
 	ubi_msg("mtd%d is detached from ubi%d", ubi->mtd->index, ubi->ubi_num);
@@ -1199,6 +1213,11 @@ static int __init ubi_init(void)
 	if (!ubi_wl_entry_slab)
 		goto out_dev_unreg;
 
+	err = ubi_debugfs_init();
+	if (err)
+		goto out_slab;
+
+
 	/* Attach MTD devices */
 	for (i = 0; i < mtd_devs; i++) {
 		struct mtd_dev_param *p = &mtd_dev_param[i];
@@ -1247,6 +1266,8 @@ static int __init ubi_init(void)
 			ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1);
 			mutex_unlock(&ubi_devices_mutex);
 		}
+	ubi_debugfs_exit();
+out_slab:
 	kmem_cache_destroy(ubi_wl_entry_slab);
 out_dev_unreg:
 	misc_deregister(&ubi_ctrl_cdev);
@@ -1270,6 +1291,7 @@ static void __exit ubi_exit(void)
 			ubi_detach_mtd_dev(ubi_devices[i]->ubi_num, 1);
 			mutex_unlock(&ubi_devices_mutex);
 		}
+	ubi_debugfs_exit();
 	kmem_cache_destroy(ubi_wl_entry_slab);
 	misc_deregister(&ubi_ctrl_cdev);
 	class_remove_file(ubi_class, &ubi_version);

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 @@ void ubi_dbg_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len)
 	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 */

drivers/mtd/ubi/debug.h

@@ -71,24 +71,42 @@ void ubi_dbg_dump_sv(const struct ubi_scan_volume *sv);
 void ubi_dbg_dump_seb(const struct ubi_scan_leb *seb, int type);
 void ubi_dbg_dump_mkvol_req(const struct ubi_mkvol_req *req);
 void ubi_dbg_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len);
-
-extern unsigned int ubi_chk_flags;
+int ubi_dbg_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len);
+int ubi_dbg_check_write(struct ubi_device *ubi, const void *buf, int pnum,
+			int offset, int len);
+int ubi_debugging_init_dev(struct ubi_device *ubi);
+void ubi_debugging_exit_dev(struct ubi_device *ubi);
+int ubi_debugfs_init(void);
+void ubi_debugfs_exit(void);
+int ubi_debugfs_init_dev(struct ubi_device *ubi);
+void ubi_debugfs_exit_dev(struct ubi_device *ubi);
 
 /*
- * Debugging check flags.
+ * The UBI debugfs directory name pattern and maximum name length (3 for "ubi"
+ * + 2 for the number plus 1 for the trailing zero byte.
+ */
+#define UBI_DFS_DIR_NAME "ubi%d"
+#define UBI_DFS_DIR_LEN  (3 + 2 + 1)
+
+/**
+ * struct ubi_debug_info - debugging information for an UBI device.
  *
- * UBI_CHK_GEN: general checks
- * UBI_CHK_IO: check writes and erases
+ * @chk_gen: if UBI general extra checks are enabled
+ * @chk_io: if UBI I/O extra checks are enabled
+ * @dfs_dir_name: name of debugfs directory containing files of this UBI device
+ * @dfs_dir: direntry object of the UBI device debugfs directory
+ * @dfs_chk_gen: debugfs knob to enable UBI general extra checks
+ * @dfs_chk_io: debugfs knob to enable UBI I/O extra checks
  */
-enum {
-	UBI_CHK_GEN = 0x1,
-	UBI_CHK_IO  = 0x2,
+struct ubi_debug_info {
+	unsigned int chk_gen:1;
+	unsigned int chk_io:1;
+	char dfs_dir_name[UBI_DFS_DIR_LEN + 1];
+	struct dentry *dfs_dir;
+	struct dentry *dfs_chk_gen;
+	struct dentry *dfs_chk_io;
 };
 
-int ubi_dbg_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len);
-int ubi_dbg_check_write(struct ubi_device *ubi, const void *buf, int pnum,
-			int offset, int len);
-
 extern unsigned int ubi_tst_flags;
 
 /*
@@ -201,11 +219,6 @@ static inline void ubi_dbg_dump_flash(struct ubi_device *ubi,
 static inline void
 ubi_dbg_print_hex_dump(const char *l, const char *ps, int pt, int r,
 		       int g, const void *b, size_t len, bool a)     { return; }
-
-static inline int ubi_dbg_is_bgt_disabled(void)                    { return 0; }
-static inline int ubi_dbg_is_bitflip(void)                         { return 0; }
-static inline int ubi_dbg_is_write_failure(void)                   { return 0; }
-static inline int ubi_dbg_is_erase_failure(void)                   { return 0; }
 static inline int ubi_dbg_check_all_ff(struct ubi_device *ubi,
 				       int pnum, int offset,
 				       int len)                    { return 0; }
@@ -213,5 +226,17 @@ static inline int ubi_dbg_check_write(struct ubi_device *ubi,
 				      const void *buf, int pnum,
 				      int offset, int len)         { return 0; }
 
+static inline int ubi_debugging_init_dev(struct ubi_device *ubi)   { return 0; }
+static inline void ubi_debugging_exit_dev(struct ubi_device *ubi)  { return; }
+static inline int ubi_debugfs_init(void)                           { return 0; }
+static inline void ubi_debugfs_exit(void)                          { return; }
+static inline int ubi_debugfs_init_dev(struct ubi_device *ubi)     { return 0; }
+static inline void ubi_debugfs_exit_dev(struct ubi_device *ubi)    { return; }
+
+static inline int ubi_dbg_is_bgt_disabled(void)                    { return 0; }
+static inline int ubi_dbg_is_bitflip(void)                         { return 0; }
+static inline int ubi_dbg_is_write_failure(void)                   { return 0; }
+static inline int ubi_dbg_is_erase_failure(void)                   { return 0; }
+
 #endif /* !CONFIG_MTD_UBI_DEBUG */
 #endif /* !__UBI_DEBUG_H__ */

drivers/mtd/ubi/io.c

@@ -1146,7 +1146,7 @@ static int paranoid_check_not_bad(const struct ubi_device *ubi, int pnum)
 {
 	int err;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	err = ubi_io_is_bad(ubi, pnum);
@@ -1173,7 +1173,7 @@ static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
 	int err;
 	uint32_t magic;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	magic = be32_to_cpu(ec_hdr->magic);
@@ -1211,7 +1211,7 @@ static int paranoid_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum)
 	uint32_t crc, hdr_crc;
 	struct ubi_ec_hdr *ec_hdr;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
@@ -1255,7 +1255,7 @@ static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
 	int err;
 	uint32_t magic;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	magic = be32_to_cpu(vid_hdr->magic);
@@ -1296,7 +1296,7 @@ static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum)
 	struct ubi_vid_hdr *vid_hdr;
 	void *p;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
@@ -1348,7 +1348,7 @@ int ubi_dbg_check_write(struct ubi_device *ubi, const void *buf, int pnum,
 	void *buf1;
 	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	buf1 = __vmalloc(len, GFP_NOFS, PAGE_KERNEL);
@@ -1412,7 +1412,7 @@ int ubi_dbg_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len)
 	void *buf;
 	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
 
-	if (!(ubi_chk_flags & UBI_CHK_IO))
+	if (!ubi->dbg->chk_io)
 		return 0;
 
 	buf = __vmalloc(len, GFP_NOFS, PAGE_KERNEL);

drivers/mtd/ubi/scan.c

@@ -1347,7 +1347,7 @@ static int paranoid_check_si(struct ubi_device *ubi, struct ubi_scan_info *si)
 	struct ubi_scan_leb *seb, *last_seb;
 	uint8_t *buf;
 
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	/*

drivers/mtd/ubi/ubi.h

@@ -390,6 +390,8 @@ struct ubi_wl_entry;
  * @peb_buf2: another buffer of PEB size used for different purposes
  * @buf_mutex: protects @peb_buf1 and @peb_buf2
  * @ckvol_mutex: serializes static volume checking when opening
+ *
+ * @dbg: debugging information for this UBI device
  */
 struct ubi_device {
 	struct cdev cdev;
@@ -472,6 +474,8 @@ struct ubi_device {
 	void *peb_buf2;
 	struct mutex buf_mutex;
 	struct mutex ckvol_mutex;
+
+	struct ubi_debug_info *dbg;
 };
 
 extern struct kmem_cache *ubi_wl_entry_slab;

drivers/mtd/ubi/vmt.c

@@ -871,7 +871,7 @@ static int paranoid_check_volumes(struct ubi_device *ubi)
 {
 	int i, err = 0;
 
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	for (i = 0; i < ubi->vtbl_slots; i++) {

drivers/mtd/ubi/vtbl.c

@@ -876,7 +876,7 @@ int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_scan_info *si)
  */
 static void paranoid_vtbl_check(const struct ubi_device *ubi)
 {
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return;
 
 	if (vtbl_check(ubi, ubi->vtbl)) {

drivers/mtd/ubi/wl.c

@@ -1582,7 +1582,7 @@ static int paranoid_check_ec(struct ubi_device *ubi, int pnum, int ec)
 	long long read_ec;
 	struct ubi_ec_hdr *ec_hdr;
 
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
@@ -1623,7 +1623,7 @@ static int paranoid_check_in_wl_tree(const struct ubi_device *ubi,
 				     struct ubi_wl_entry *e,
 				     struct rb_root *root)
 {
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	if (in_wl_tree(e, root))
@@ -1649,7 +1649,7 @@ static int paranoid_check_in_pq(const struct ubi_device *ubi,
 	struct ubi_wl_entry *p;
 	int i;
 
-	if (!(ubi_chk_flags & UBI_CHK_GEN))
+	if (!ubi->dbg->chk_gen)
 		return 0;
 
 	for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i)