Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 697 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
new file mode 100644
index 000000000..d2a53961d
--- /dev/null
+++ b/drivers/mtd/ubi/debug.c
@@ -0,0 +1,697 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+#include "ubi.h"
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <linux/fault-inject.h>
+
+#ifdef CONFIG_MTD_UBI_FAULT_INJECTION
+static DECLARE_FAULT_ATTR(fault_eccerr_attr);
+static DECLARE_FAULT_ATTR(fault_bitflips_attr);
+static DECLARE_FAULT_ATTR(fault_read_failure_attr);
+static DECLARE_FAULT_ATTR(fault_write_failure_attr);
+static DECLARE_FAULT_ATTR(fault_erase_failure_attr);
+static DECLARE_FAULT_ATTR(fault_power_cut_attr);
+static DECLARE_FAULT_ATTR(fault_io_ff_attr);
+static DECLARE_FAULT_ATTR(fault_io_ff_bitflips_attr);
+static DECLARE_FAULT_ATTR(fault_bad_hdr_attr);
+static DECLARE_FAULT_ATTR(fault_bad_hdr_ebadmsg_attr);
+
+#define FAIL_ACTION(name, fault_attr)			\
+bool should_fail_##name(void)				\
+{							\
+	return should_fail(&fault_attr, 1);		\
+}
+
+FAIL_ACTION(eccerr,		fault_eccerr_attr)
+FAIL_ACTION(bitflips,		fault_bitflips_attr)
+FAIL_ACTION(read_failure,	fault_read_failure_attr)
+FAIL_ACTION(write_failure,	fault_write_failure_attr)
+FAIL_ACTION(erase_failure,	fault_erase_failure_attr)
+FAIL_ACTION(power_cut,		fault_power_cut_attr)
+FAIL_ACTION(io_ff,		fault_io_ff_attr)
+FAIL_ACTION(io_ff_bitflips,	fault_io_ff_bitflips_attr)
+FAIL_ACTION(bad_hdr,		fault_bad_hdr_attr)
+FAIL_ACTION(bad_hdr_ebadmsg,	fault_bad_hdr_ebadmsg_attr)
+#endif
+
+/**
+ * ubi_dump_flash - dump a region of flash.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to dump
+ * @offset: the starting offset within the physical eraseblock to dump
+ * @len: the length of the region to dump
+ */
+void ubi_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len)
+{
+	int err;
+	size_t read;
+	void *buf;
+	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
+
+	buf = vmalloc(len);
+	if (!buf)
+		return;
+	err = mtd_read(ubi->mtd, addr, len, &read, buf);
+	if (err && err != -EUCLEAN) {
+		ubi_err(ubi, "err %d while reading %d bytes from PEB %d:%d, read %zd bytes",
+			err, len, pnum, offset, read);
+		goto out;
+	}
+
+	ubi_msg(ubi, "dumping %d bytes of data from PEB %d, offset %d",
+		len, pnum, offset);
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1, buf, len, 1);
+out:
+	vfree(buf);
+	return;
+}
+
+/**
+ * ubi_dump_ec_hdr - dump an erase counter header.
+ * @ec_hdr: the erase counter header to dump
+ */
+void ubi_dump_ec_hdr(const struct ubi_ec_hdr *ec_hdr)
+{
+	pr_err("Erase counter header dump:\n");
+	pr_err("\tmagic          %#08x\n", be32_to_cpu(ec_hdr->magic));
+	pr_err("\tversion        %d\n", (int)ec_hdr->version);
+	pr_err("\tec             %llu\n", (long long)be64_to_cpu(ec_hdr->ec));
+	pr_err("\tvid_hdr_offset %d\n", be32_to_cpu(ec_hdr->vid_hdr_offset));
+	pr_err("\tdata_offset    %d\n", be32_to_cpu(ec_hdr->data_offset));
+	pr_err("\timage_seq      %d\n", be32_to_cpu(ec_hdr->image_seq));
+	pr_err("\thdr_crc        %#08x\n", be32_to_cpu(ec_hdr->hdr_crc));
+	pr_err("erase counter header hexdump:\n");
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+		       ec_hdr, UBI_EC_HDR_SIZE, 1);
+}
+
+/**
+ * ubi_dump_vid_hdr - dump a volume identifier header.
+ * @vid_hdr: the volume identifier header to dump
+ */
+void ubi_dump_vid_hdr(const struct ubi_vid_hdr *vid_hdr)
+{
+	pr_err("Volume identifier header dump:\n");
+	pr_err("\tmagic     %08x\n", be32_to_cpu(vid_hdr->magic));
+	pr_err("\tversion   %d\n",  (int)vid_hdr->version);
+	pr_err("\tvol_type  %d\n",  (int)vid_hdr->vol_type);
+	pr_err("\tcopy_flag %d\n",  (int)vid_hdr->copy_flag);
+	pr_err("\tcompat    %d\n",  (int)vid_hdr->compat);
+	pr_err("\tvol_id    %d\n",  be32_to_cpu(vid_hdr->vol_id));
+	pr_err("\tlnum      %d\n",  be32_to_cpu(vid_hdr->lnum));
+	pr_err("\tdata_size %d\n",  be32_to_cpu(vid_hdr->data_size));
+	pr_err("\tused_ebs  %d\n",  be32_to_cpu(vid_hdr->used_ebs));
+	pr_err("\tdata_pad  %d\n",  be32_to_cpu(vid_hdr->data_pad));
+	pr_err("\tsqnum     %llu\n",
+		(unsigned long long)be64_to_cpu(vid_hdr->sqnum));
+	pr_err("\thdr_crc   %08x\n", be32_to_cpu(vid_hdr->hdr_crc));
+	pr_err("Volume identifier header hexdump:\n");
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+		       vid_hdr, UBI_VID_HDR_SIZE, 1);
+}
+
+/**
+ * ubi_dump_vol_info - dump volume information.
+ * @vol: UBI volume description object
+ */
+void ubi_dump_vol_info(const struct ubi_volume *vol)
+{
+	pr_err("Volume information dump:\n");
+	pr_err("\tvol_id          %d\n", vol->vol_id);
+	pr_err("\treserved_pebs   %d\n", vol->reserved_pebs);
+	pr_err("\talignment       %d\n", vol->alignment);
+	pr_err("\tdata_pad        %d\n", vol->data_pad);
+	pr_err("\tvol_type        %d\n", vol->vol_type);
+	pr_err("\tname_len        %d\n", vol->name_len);
+	pr_err("\tusable_leb_size %d\n", vol->usable_leb_size);
+	pr_err("\tused_ebs        %d\n", vol->used_ebs);
+	pr_err("\tused_bytes      %lld\n", vol->used_bytes);
+	pr_err("\tlast_eb_bytes   %d\n", vol->last_eb_bytes);
+	pr_err("\tcorrupted       %d\n", vol->corrupted);
+	pr_err("\tupd_marker      %d\n", vol->upd_marker);
+	pr_err("\tskip_check      %d\n", vol->skip_check);
+
+	if (vol->name_len <= UBI_VOL_NAME_MAX &&
+	    strnlen(vol->name, vol->name_len + 1) == vol->name_len) {
+		pr_err("\tname            %s\n", vol->name);
+	} else {
+		pr_err("\t1st 5 characters of name: %c%c%c%c%c\n",
+		       vol->name[0], vol->name[1], vol->name[2],
+		       vol->name[3], vol->name[4]);
+	}
+}
+
+/**
+ * ubi_dump_vtbl_record - dump a &struct ubi_vtbl_record object.
+ * @r: the object to dump
+ * @idx: volume table index
+ */
+void ubi_dump_vtbl_record(const struct ubi_vtbl_record *r, int idx)
+{
+	int name_len = be16_to_cpu(r->name_len);
+
+	pr_err("Volume table record %d dump:\n", idx);
+	pr_err("\treserved_pebs   %d\n", be32_to_cpu(r->reserved_pebs));
+	pr_err("\talignment       %d\n", be32_to_cpu(r->alignment));
+	pr_err("\tdata_pad        %d\n", be32_to_cpu(r->data_pad));
+	pr_err("\tvol_type        %d\n", (int)r->vol_type);
+	pr_err("\tupd_marker      %d\n", (int)r->upd_marker);
+	pr_err("\tname_len        %d\n", name_len);
+
+	if (r->name[0] == '\0') {
+		pr_err("\tname            NULL\n");
+		return;
+	}
+
+	if (name_len <= UBI_VOL_NAME_MAX &&
+	    strnlen(&r->name[0], name_len + 1) == name_len) {
+		pr_err("\tname            %s\n", &r->name[0]);
+	} else {
+		pr_err("\t1st 5 characters of name: %c%c%c%c%c\n",
+			r->name[0], r->name[1], r->name[2], r->name[3],
+			r->name[4]);
+	}
+	pr_err("\tcrc             %#08x\n", be32_to_cpu(r->crc));
+}
+
+/**
+ * ubi_dump_av - dump a &struct ubi_ainf_volume object.
+ * @av: the object to dump
+ */
+void ubi_dump_av(const struct ubi_ainf_volume *av)
+{
+	pr_err("Volume attaching information dump:\n");
+	pr_err("\tvol_id         %d\n", av->vol_id);
+	pr_err("\thighest_lnum   %d\n", av->highest_lnum);
+	pr_err("\tleb_count      %d\n", av->leb_count);
+	pr_err("\tcompat         %d\n", av->compat);
+	pr_err("\tvol_type       %d\n", av->vol_type);
+	pr_err("\tused_ebs       %d\n", av->used_ebs);
+	pr_err("\tlast_data_size %d\n", av->last_data_size);
+	pr_err("\tdata_pad       %d\n", av->data_pad);
+}
+
+/**
+ * ubi_dump_aeb - dump a &struct ubi_ainf_peb object.
+ * @aeb: the object to dump
+ * @type: object type: 0 - not corrupted, 1 - corrupted
+ */
+void ubi_dump_aeb(const struct ubi_ainf_peb *aeb, int type)
+{
+	pr_err("eraseblock attaching information dump:\n");
+	pr_err("\tec       %d\n", aeb->ec);
+	pr_err("\tpnum     %d\n", aeb->pnum);
+	if (type == 0) {
+		pr_err("\tlnum     %d\n", aeb->lnum);
+		pr_err("\tscrub    %d\n", aeb->scrub);
+		pr_err("\tsqnum    %llu\n", aeb->sqnum);
+	}
+}
+
+/**
+ * ubi_dump_mkvol_req - dump a &struct ubi_mkvol_req object.
+ * @req: the object to dump
+ */
+void ubi_dump_mkvol_req(const struct ubi_mkvol_req *req)
+{
+	char nm[17];
+
+	pr_err("Volume creation request dump:\n");
+	pr_err("\tvol_id    %d\n",   req->vol_id);
+	pr_err("\talignment %d\n",   req->alignment);
+	pr_err("\tbytes     %lld\n", (long long)req->bytes);
+	pr_err("\tvol_type  %d\n",   req->vol_type);
+	pr_err("\tname_len  %d\n",   req->name_len);
+
+	memcpy(nm, req->name, 16);
+	nm[16] = 0;
+	pr_err("\t1st 16 characters of name: %s\n", nm);
+}
+
+/*
+ * Root directory for UBI stuff in debugfs. Contains sub-directories which
+ * contain the stuff specific to particular UBI devices.
+ */
+static struct dentry *dfs_rootdir;
+
+#ifdef CONFIG_MTD_UBI_FAULT_INJECTION
+static void dfs_create_fault_entry(struct dentry *parent)
+{
+	struct dentry *dir;
+
+	dir = debugfs_create_dir("fault_inject", parent);
+	if (IS_ERR_OR_NULL(dir)) {
+		int err = dir ? PTR_ERR(dir) : -ENODEV;
+
+		pr_warn("UBI error: cannot create \"fault_inject\" debugfs directory, error %d\n",
+			 err);
+		return;
+	}
+
+	fault_create_debugfs_attr("emulate_eccerr", dir,
+				  &fault_eccerr_attr);
+
+	fault_create_debugfs_attr("emulate_read_failure", dir,
+				  &fault_read_failure_attr);
+
+	fault_create_debugfs_attr("emulate_bitflips", dir,
+				  &fault_bitflips_attr);
+
+	fault_create_debugfs_attr("emulate_write_failure", dir,
+				  &fault_write_failure_attr);
+
+	fault_create_debugfs_attr("emulate_erase_failure", dir,
+				  &fault_erase_failure_attr);
+
+	fault_create_debugfs_attr("emulate_power_cut", dir,
+				  &fault_power_cut_attr);
+
+	fault_create_debugfs_attr("emulate_io_ff", dir,
+				  &fault_io_ff_attr);
+
+	fault_create_debugfs_attr("emulate_io_ff_bitflips", dir,
+				  &fault_io_ff_bitflips_attr);
+
+	fault_create_debugfs_attr("emulate_bad_hdr", dir,
+				  &fault_bad_hdr_attr);
+
+	fault_create_debugfs_attr("emulate_bad_hdr_ebadmsg", dir,
+				  &fault_bad_hdr_ebadmsg_attr);
+}
+#endif
+
+/**
+ * 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)
+{
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
+		return 0;
+
+	dfs_rootdir = debugfs_create_dir("ubi", NULL);
+	if (IS_ERR_OR_NULL(dfs_rootdir)) {
+		int err = dfs_rootdir ? PTR_ERR(dfs_rootdir) : -ENODEV;
+
+		pr_err("UBI error: cannot create \"ubi\" debugfs directory, error %d\n",
+		       err);
+		return err;
+	}
+
+#ifdef CONFIG_MTD_UBI_FAULT_INJECTION
+	dfs_create_fault_entry(dfs_rootdir);
+#endif
+
+	return 0;
+}
+
+/**
+ * ubi_debugfs_exit - remove UBI debugfs directory.
+ */
+void ubi_debugfs_exit(void)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		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[16];
+	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 if (dent == d->dfs_chk_fastmap)
+		val = d->chk_fastmap;
+	else if (dent == d->dfs_disable_bgt)
+		val = d->disable_bgt;
+	else if (dent == d->dfs_emulate_bitflips)
+		val = d->emulate_bitflips;
+	else if (dent == d->dfs_emulate_io_failures)
+		val = d->emulate_io_failures;
+	else if (dent == d->dfs_emulate_failures) {
+		snprintf(buf, sizeof(buf), "0x%04x\n", d->emulate_failures);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	} else if (dent == d->dfs_emulate_power_cut) {
+		snprintf(buf, sizeof(buf), "%u\n", d->emulate_power_cut);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	} else if (dent == d->dfs_power_cut_min) {
+		snprintf(buf, sizeof(buf), "%u\n", d->power_cut_min);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	} else if (dent == d->dfs_power_cut_max) {
+		snprintf(buf, sizeof(buf), "%u\n", d->power_cut_max);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	} 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[16] = {0};
+	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 (dent == d->dfs_emulate_failures) {
+		if (kstrtouint(buf, 0, &d->emulate_failures) != 0)
+			count = -EINVAL;
+		goto out;
+	} else if (dent == d->dfs_power_cut_min) {
+		if (kstrtouint(buf, 0, &d->power_cut_min) != 0)
+			count = -EINVAL;
+		goto out;
+	} else if (dent == d->dfs_power_cut_max) {
+		if (kstrtouint(buf, 0, &d->power_cut_max) != 0)
+			count = -EINVAL;
+		goto out;
+	} else if (dent == d->dfs_emulate_power_cut) {
+		if (kstrtoint(buf, 0, &val) != 0)
+			count = -EINVAL;
+		else
+			d->emulate_power_cut = val;
+		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 if (dent == d->dfs_chk_fastmap)
+		d->chk_fastmap = val;
+	else if (dent == d->dfs_disable_bgt)
+		d->disable_bgt = val;
+	else if (dent == d->dfs_emulate_bitflips)
+		d->emulate_bitflips = val;
+	else if (dent == d->dfs_emulate_io_failures)
+		d->emulate_io_failures = val;
+	else
+		count = -EINVAL;
+
+out:
+	ubi_put_device(ubi);
+	return count;
+}
+
+/* File operations for all UBI debugfs files except
+ * detailed_erase_block_info
+ */
+static const struct file_operations dfs_fops = {
+	.read   = dfs_file_read,
+	.write  = dfs_file_write,
+	.open	= simple_open,
+	.owner  = THIS_MODULE,
+};
+
+/* As long as the position is less then that total number of erase blocks,
+ * we still have more to print.
+ */
+static void *eraseblk_count_seq_start(struct seq_file *s, loff_t *pos)
+{
+	struct ubi_device *ubi = s->private;
+
+	if (*pos < ubi->peb_count)
+		return pos;
+
+	return NULL;
+}
+
+/* Since we are using the position as the iterator, we just need to check if we
+ * are done and increment the position.
+ */
+static void *eraseblk_count_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct ubi_device *ubi = s->private;
+
+	(*pos)++;
+
+	if (*pos < ubi->peb_count)
+		return pos;
+
+	return NULL;
+}
+
+static void eraseblk_count_seq_stop(struct seq_file *s, void *v)
+{
+}
+
+static int eraseblk_count_seq_show(struct seq_file *s, void *iter)
+{
+	struct ubi_device *ubi = s->private;
+	struct ubi_wl_entry *wl;
+	int *block_number = iter;
+	int erase_count = -1;
+	int err;
+
+	/* If this is the start, print a header */
+	if (*block_number == 0)
+		seq_puts(s, "physical_block_number\terase_count\n");
+
+	err = ubi_io_is_bad(ubi, *block_number);
+	if (err)
+		return err;
+
+	spin_lock(&ubi->wl_lock);
+
+	wl = ubi->lookuptbl[*block_number];
+	if (wl)
+		erase_count = wl->ec;
+
+	spin_unlock(&ubi->wl_lock);
+
+	if (erase_count < 0)
+		return 0;
+
+	seq_printf(s, "%-22d\t%-11d\n", *block_number, erase_count);
+
+	return 0;
+}
+
+static const struct seq_operations eraseblk_count_seq_ops = {
+	.start = eraseblk_count_seq_start,
+	.next = eraseblk_count_seq_next,
+	.stop = eraseblk_count_seq_stop,
+	.show = eraseblk_count_seq_show
+};
+
+static int eraseblk_count_open(struct inode *inode, struct file *f)
+{
+	struct seq_file *s;
+	int err;
+
+	err = seq_open(f, &eraseblk_count_seq_ops);
+	if (err)
+		return err;
+
+	s = f->private_data;
+	s->private = ubi_get_device((unsigned long)inode->i_private);
+
+	if (!s->private)
+		return -ENODEV;
+	else
+		return 0;
+}
+
+static int eraseblk_count_release(struct inode *inode, struct file *f)
+{
+	struct seq_file *s = f->private_data;
+	struct ubi_device *ubi = s->private;
+
+	ubi_put_device(ubi);
+
+	return seq_release(inode, f);
+}
+
+static const struct file_operations eraseblk_count_fops = {
+	.owner = THIS_MODULE,
+	.open = eraseblk_count_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = eraseblk_count_release,
+};
+
+/**
+ * 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)
+{
+	unsigned long ubi_num = ubi->ubi_num;
+	struct ubi_debug_info *d = &ubi->dbg;
+	umode_t mode = S_IRUSR | S_IWUSR;
+	int n;
+
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
+		return 0;
+
+	n = snprintf(d->dfs_dir_name, UBI_DFS_DIR_LEN, UBI_DFS_DIR_NAME,
+		     ubi->ubi_num);
+	if (n >= UBI_DFS_DIR_LEN) {
+		/* The array size is too small */
+		return -EINVAL;
+	}
+
+	d->dfs_dir = debugfs_create_dir(d->dfs_dir_name, dfs_rootdir);
+
+	d->dfs_chk_gen = debugfs_create_file("chk_gen", mode, d->dfs_dir,
+					     (void *)ubi_num, &dfs_fops);
+
+	d->dfs_chk_io = debugfs_create_file("chk_io", mode, d->dfs_dir,
+					    (void *)ubi_num, &dfs_fops);
+
+	d->dfs_chk_fastmap = debugfs_create_file("chk_fastmap", mode,
+						 d->dfs_dir, (void *)ubi_num,
+						 &dfs_fops);
+
+	d->dfs_disable_bgt = debugfs_create_file("tst_disable_bgt", mode,
+						 d->dfs_dir, (void *)ubi_num,
+						 &dfs_fops);
+
+	d->dfs_emulate_bitflips = debugfs_create_file("tst_emulate_bitflips",
+						      mode, d->dfs_dir,
+						      (void *)ubi_num,
+						      &dfs_fops);
+
+	d->dfs_emulate_io_failures = debugfs_create_file("tst_emulate_io_failures",
+							 mode, d->dfs_dir,
+							 (void *)ubi_num,
+							 &dfs_fops);
+
+	d->dfs_emulate_power_cut = debugfs_create_file("tst_emulate_power_cut",
+						       mode, d->dfs_dir,
+						       (void *)ubi_num,
+						       &dfs_fops);
+
+	d->dfs_power_cut_min = debugfs_create_file("tst_emulate_power_cut_min",
+						   mode, d->dfs_dir,
+						   (void *)ubi_num, &dfs_fops);
+
+	d->dfs_power_cut_max = debugfs_create_file("tst_emulate_power_cut_max",
+						   mode, d->dfs_dir,
+						   (void *)ubi_num, &dfs_fops);
+
+	debugfs_create_file("detailed_erase_block_info", S_IRUSR, d->dfs_dir,
+			    (void *)ubi_num, &eraseblk_count_fops);
+
+#ifdef CONFIG_MTD_UBI_FAULT_INJECTION
+	d->dfs_emulate_failures = debugfs_create_file("emulate_failures",
+						       mode, d->dfs_dir,
+						       (void *)ubi_num,
+						       &dfs_fops);
+#endif
+	return 0;
+}
+
+/**
+ * ubi_debugfs_exit_dev - free all debugfs files corresponding to device @ubi
+ * @ubi: UBI device description object
+ */
+void ubi_debugfs_exit_dev(struct ubi_device *ubi)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		debugfs_remove_recursive(ubi->dbg.dfs_dir);
+}
+
+/**
+ * ubi_dbg_power_cut - emulate a power cut if it is time to do so
+ * @ubi: UBI device description object
+ * @caller: Flags set to indicate from where the function is being called
+ *
+ * Returns non-zero if a power cut was emulated, zero if not.
+ */
+int ubi_dbg_power_cut(struct ubi_device *ubi, int caller)
+{
+	unsigned int range;
+
+	if ((ubi->dbg.emulate_power_cut & caller) == 0)
+		return 0;
+
+	if (ubi->dbg.power_cut_counter == 0) {
+		ubi->dbg.power_cut_counter = ubi->dbg.power_cut_min;
+
+		if (ubi->dbg.power_cut_max > ubi->dbg.power_cut_min) {
+			range = ubi->dbg.power_cut_max - ubi->dbg.power_cut_min;
+			ubi->dbg.power_cut_counter += get_random_u32_below(range);
+		}
+		return 0;
+	}
+
+	ubi->dbg.power_cut_counter--;
+	if (ubi->dbg.power_cut_counter)
+		return 0;
+
+	return 1;
+}