ubi: Use the fault injection framework to enhance the fault injection capability

To make debug parameters configurable at run time, use the
fault injection framework to reconstruct the debugfs interface,
and retain the legacy fault injection interface.

Now, the file emulate_failures and fault_attr files control whether
to enable fault emmulation.

The file emulate_failures receives a mask that controls type and
process of fault injection. Generally, for ease of use, you can
directly enter a mask with all 1s.

echo 0xffff > /sys/kernel/debug/ubi/ubi0/emulate_failures

And you need to configure other fault-injection capabilities for
testing purpose:

echo 100 > /sys/kernel/debug/ubi/fault_inject/emulate_power_cut/probability
echo 15 > /sys/kernel/debug/ubi/fault_inject/emulate_power_cut/space
echo 2 > /sys/kernel/debug/ubi/fault_inject/emulate_power_cut/verbose
echo -1 > /sys/kernel/debug/ubi/fault_inject/emulate_power_cut/times

The CONFIG_MTD_UBI_FAULT_INJECTION to enable the Fault Injection is
added to kconfig.

Signed-off-by: ZhaoLong Wang <wangzhaolong1@huawei.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

5 files changed, 203 insertions, 42 deletions

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index 2ed77b7b3fcb..7499a540121e 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -104,4 +104,13 @@ config MTD_UBI_BLOCK
 
 	   If in doubt, say "N".
 
+config MTD_UBI_FAULT_INJECTION
+	bool "Fault injection capability of UBI device"
+	default n
+	depends on FAULT_INJECTION_DEBUG_FS
+	help
+	   This option enables fault-injection support for UBI devices for
+	   testing purposes.
+
+	   If in doubt, say "N".
 endif # MTD_UBI
diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
index 27168f511d6d..fd101ad6f12f 100644
--- a/drivers/mtd/ubi/debug.c
+++ b/drivers/mtd/ubi/debug.c
@@ -10,7 +10,23 @@
 #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_bitflips_attr);
+static DECLARE_FAULT_ATTR(fault_io_failures_attr);
+static DECLARE_FAULT_ATTR(fault_power_cut_attr);
+
+#define FAIL_ACTION(name, fault_attr)			\
+bool should_fail_##name(void)				\
+{							\
+	return should_fail(&fault_attr, 1);		\
+}
+
+FAIL_ACTION(bitflips,		fault_bitflips_attr)
+FAIL_ACTION(io_failures,	fault_io_failures_attr)
+FAIL_ACTION(power_cut,		fault_power_cut_attr)
+#endif
 
 /**
  * ubi_dump_flash - dump a region of flash.
@@ -212,6 +228,31 @@ void ubi_dump_mkvol_req(const struct ubi_mkvol_req *req)
  */
 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_bitflips", dir,
+				  &fault_bitflips_attr);
+
+	fault_create_debugfs_attr("emulate_io_failures", dir,
+				  &fault_io_failures_attr);
+
+	fault_create_debugfs_attr("emulate_power_cut", dir,
+				  &fault_power_cut_attr);
+}
+#endif
+
 /**
  * ubi_debugfs_init - create UBI debugfs directory.
  *
@@ -232,6 +273,10 @@ int ubi_debugfs_init(void)
 		return err;
 	}
 
+#ifdef CONFIG_MTD_UBI_FAULT_INJECTION
+	dfs_create_fault_entry(dfs_rootdir);
+#endif
+
 	return 0;
 }
 
@@ -272,7 +317,12 @@ static ssize_t dfs_file_read(struct file *file, char __user *user_buf,
 		val = d->emulate_bitflips;
 	else if (dent == d->dfs_emulate_io_failures)
 		val = d->emulate_io_failures;
-	else if (dent == d->dfs_emulate_power_cut) {
+	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));
@@ -287,8 +337,7 @@ static ssize_t dfs_file_read(struct file *file, char __user *user_buf,
 		count = simple_read_from_buffer(user_buf, count, ppos,
 						buf, strlen(buf));
 		goto out;
-	}
-	else {
+	} else {
 		count = -EINVAL;
 		goto out;
 	}
@@ -330,7 +379,11 @@ static ssize_t dfs_file_write(struct file *file, const char __user *user_buf,
 		goto out;
 	}
 
-	if (dent == d->dfs_power_cut_min) {
+	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;
@@ -559,6 +612,12 @@ int ubi_debugfs_init_dev(struct ubi_device *ubi)
 	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;
 }
 
@@ -600,7 +659,5 @@ int ubi_dbg_power_cut(struct ubi_device *ubi, int caller)
 	if (ubi->dbg.power_cut_counter)
 		return 0;
 
-	ubi_msg(ubi, "XXXXXXXXXXXXXXX emulating a power cut XXXXXXXXXXXXXXXX");
-	ubi_ro_mode(ubi);
 	return 1;
 }
diff --git a/drivers/mtd/ubi/debug.h b/drivers/mtd/ubi/debug.h
index 23676f32b681..f2f499feff49 100644
--- a/drivers/mtd/ubi/debug.h
+++ b/drivers/mtd/ubi/debug.h
@@ -53,56 +53,153 @@ int ubi_debugfs_init_dev(struct ubi_device *ubi);
 void ubi_debugfs_exit_dev(struct ubi_device *ubi);
 
 /**
- * ubi_dbg_is_bgt_disabled - if the background thread is disabled.
+ * The following function is a legacy implementation of UBI fault-injection
+ * hook. When using more powerful fault injection capabilities, the legacy
+ * fault injection interface should be retained.
+ */
+int ubi_dbg_power_cut(struct ubi_device *ubi, int caller);
+
+static inline int ubi_dbg_bitflip(const struct ubi_device *ubi)
+{
+	if (ubi->dbg.emulate_bitflips)
+		return !get_random_u32_below(200);
+	return 0;
+}
+
+static inline int ubi_dbg_write_failure(const struct ubi_device *ubi)
+{
+	if (ubi->dbg.emulate_io_failures)
+		return !get_random_u32_below(500);
+	return 0;
+}
+
+static inline int ubi_dbg_erase_failure(const struct ubi_device *ubi)
+{
+	if (ubi->dbg.emulate_io_failures)
+		return !get_random_u32_below(400);
+	return 0;
+}
+
+/**
+ * MASK_XXX: Mask for emulate_failures in ubi_debug_info.The mask is used to
+ * precisely control the type and process of fault injection.
+ */
+/* Emulate a power cut when writing EC/VID header */
+#define MASK_POWER_CUT_EC			(1 << 0)
+#define MASK_POWER_CUT_VID			(1 << 1)
+
+#ifdef CONFIG_MTD_UBI_FAULT_INJECTION
+/* Emulate bit-flips */
+#define MASK_BITFLIPS				(1 << 2)
+/* Emulates -EIO during write/erase */
+#define MASK_IO_FAILURE				(1 << 3)
+
+extern bool should_fail_bitflips(void);
+extern bool should_fail_io_failures(void);
+extern bool should_fail_power_cut(void);
+
+static inline bool ubi_dbg_fail_bitflip(const struct ubi_device *ubi)
+{
+	if (ubi->dbg.emulate_failures & MASK_BITFLIPS)
+		return should_fail_bitflips();
+	return false;
+}
+
+static inline bool ubi_dbg_fail_write(const struct ubi_device *ubi)
+{
+	if (ubi->dbg.emulate_failures & MASK_IO_FAILURE)
+		return should_fail_io_failures();
+	return false;
+}
+
+static inline bool ubi_dbg_fail_erase(const struct ubi_device *ubi)
+{
+	if (ubi->dbg.emulate_failures & MASK_IO_FAILURE)
+		return should_fail_io_failures();
+	return false;
+}
+
+static inline bool ubi_dbg_fail_power_cut(const struct ubi_device *ubi,
+					unsigned int caller)
+{
+	if (ubi->dbg.emulate_failures & caller)
+		return should_fail_power_cut();
+	return false;
+}
+
+#else /* CONFIG_MTD_UBI_FAULT_INJECTION */
+
+#define ubi_dbg_fail_bitflip(u)             false
+#define ubi_dbg_fail_write(u)               false
+#define ubi_dbg_fail_erase(u)               false
+#define ubi_dbg_fail_power_cut(u, c)        false
+#endif
+
+/**
+ * ubi_dbg_is_power_cut - if it is time to emulate power cut.
  * @ubi: UBI device description object
  *
- * Returns non-zero if the UBI background thread is disabled for testing
- * purposes.
+ * Returns true if power cut should be emulated, otherwise returns false.
  */
-static inline int ubi_dbg_is_bgt_disabled(const struct ubi_device *ubi)
+static inline bool ubi_dbg_is_power_cut(struct ubi_device *ubi,
+					unsigned int caller)
 {
-	return ubi->dbg.disable_bgt;
+	if (ubi_dbg_power_cut(ubi, caller))
+		return true;
+	return ubi_dbg_fail_power_cut(ubi, caller);
 }
 
 /**
  * ubi_dbg_is_bitflip - if it is time to emulate a bit-flip.
  * @ubi: UBI device description object
  *
- * Returns non-zero if a bit-flip should be emulated, otherwise returns zero.
+ * Returns true if a bit-flip should be emulated, otherwise returns false.
  */
-static inline int ubi_dbg_is_bitflip(const struct ubi_device *ubi)
+static inline bool ubi_dbg_is_bitflip(const struct ubi_device *ubi)
 {
-	if (ubi->dbg.emulate_bitflips)
-		return !get_random_u32_below(200);
-	return 0;
+	if (ubi_dbg_bitflip(ubi))
+		return true;
+	return ubi_dbg_fail_bitflip(ubi);
 }
 
 /**
  * ubi_dbg_is_write_failure - if it is time to emulate a write failure.
  * @ubi: UBI device description object
  *
- * Returns non-zero if a write failure should be emulated, otherwise returns
- * zero.
+ * Returns true if a write failure should be emulated, otherwise returns
+ * false.
  */
-static inline int ubi_dbg_is_write_failure(const struct ubi_device *ubi)
+static inline bool ubi_dbg_is_write_failure(const struct ubi_device *ubi)
 {
-	if (ubi->dbg.emulate_io_failures)
-		return !get_random_u32_below(500);
-	return 0;
+	if (ubi_dbg_write_failure(ubi))
+		return true;
+	return ubi_dbg_fail_write(ubi);
 }
 
 /**
  * ubi_dbg_is_erase_failure - if its time to emulate an erase failure.
  * @ubi: UBI device description object
  *
- * Returns non-zero if an erase failure should be emulated, otherwise returns
- * zero.
+ * Returns true if an erase failure should be emulated, otherwise returns
+ * false.
  */
-static inline int ubi_dbg_is_erase_failure(const struct ubi_device *ubi)
+static inline bool ubi_dbg_is_erase_failure(const struct ubi_device *ubi)
 {
-	if (ubi->dbg.emulate_io_failures)
-		return !get_random_u32_below(400);
-	return 0;
+	if (ubi_dbg_erase_failure(ubi))
+		return true;
+	return ubi_dbg_fail_erase(ubi);
+}
+
+/**
+ * ubi_dbg_is_bgt_disabled - if the background thread is disabled.
+ * @ubi: UBI device description object
+ *
+ * Returns non-zero if the UBI background thread is disabled for testing
+ * purposes.
+ */
+static inline int ubi_dbg_is_bgt_disabled(const struct ubi_device *ubi)
+{
+	return ubi->dbg.disable_bgt;
 }
 
 static inline int ubi_dbg_chk_io(const struct ubi_device *ubi)
@@ -125,5 +222,4 @@ static inline void ubi_enable_dbg_chk_fastmap(struct ubi_device *ubi)
 	ubi->dbg.chk_fastmap = 1;
 }
 
-int ubi_dbg_power_cut(struct ubi_device *ubi, int caller);
 #endif /* !__UBI_DEBUG_H__ */
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index 01b644861253..fb70f5227f18 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -821,8 +821,11 @@ int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,
 	if (err)
 		return err;
 
-	if (ubi_dbg_power_cut(ubi, POWER_CUT_EC_WRITE))
+	if (ubi_dbg_is_power_cut(ubi, MASK_POWER_CUT_EC)) {
+		ubi_warn(ubi, "emulating a power cut when writing EC header");
+		ubi_ro_mode(ubi);
 		return -EROFS;
+	}
 
 	err = ubi_io_write(ubi, ec_hdr, pnum, 0, ubi->ec_hdr_alsize);
 	return err;
@@ -1071,8 +1074,11 @@ int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
 	if (err)
 		return err;
 
-	if (ubi_dbg_power_cut(ubi, POWER_CUT_VID_WRITE))
+	if (ubi_dbg_is_power_cut(ubi, MASK_POWER_CUT_VID)) {
+		ubi_warn(ubi, "emulating a power cut when writing VID header");
+		ubi_ro_mode(ubi);
 		return -EROFS;
+	}
 
 	err = ubi_io_write(ubi, p, pnum, ubi->vid_hdr_aloffset,
 			   ubi->vid_hdr_alsize);
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index a5ec566df0d7..cc4777983bd2 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -145,17 +145,6 @@ enum {
 	UBI_BAD_FASTMAP,
 };
 
-/*
- * Flags for emulate_power_cut in ubi_debug_info
- *
- * POWER_CUT_EC_WRITE: Emulate a power cut when writing an EC header
- * POWER_CUT_VID_WRITE: Emulate a power cut when writing a VID header
- */
-enum {
-	POWER_CUT_EC_WRITE = 0x01,
-	POWER_CUT_VID_WRITE = 0x02,
-};
-
 /**
  * struct ubi_vid_io_buf - VID buffer used to read/write VID info to/from the
  *			   flash.
@@ -404,6 +393,7 @@ struct ubi_volume_desc {
  * @power_cut_counter: count down for writes left until emulated power cut
  * @power_cut_min: minimum number of writes before emulating a power cut
  * @power_cut_max: maximum number of writes until emulating a power cut
+ * @emulate_failures: emulate failures for testing purposes
  * @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
@@ -415,6 +405,7 @@ struct ubi_volume_desc {
  * @dfs_emulate_power_cut: debugfs knob to emulate power cuts
  * @dfs_power_cut_min: debugfs knob for minimum writes before power cut
  * @dfs_power_cut_max: debugfs knob for maximum writes until power cut
+ * @dfs_emulate_failures: debugfs entry to control the fault injection type
  */
 struct ubi_debug_info {
 	unsigned int chk_gen:1;
@@ -427,6 +418,7 @@ struct ubi_debug_info {
 	unsigned int power_cut_counter;
 	unsigned int power_cut_min;
 	unsigned int power_cut_max;
+	unsigned int emulate_failures;
 	char dfs_dir_name[UBI_DFS_DIR_LEN + 1];
 	struct dentry *dfs_dir;
 	struct dentry *dfs_chk_gen;
@@ -438,6 +430,7 @@ struct ubi_debug_info {
 	struct dentry *dfs_emulate_power_cut;
 	struct dentry *dfs_power_cut_min;
 	struct dentry *dfs_power_cut_max;
+	struct dentry *dfs_emulate_failures;
 };
 
 /**