2 files changed, 74 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/debug.h b/drivers/mtd/ubi/debug.h
index f30bcb372c05..17a107129726 100644
--- a/drivers/mtd/ubi/debug.h
+++ b/drivers/mtd/ubi/debug.h
@@ -96,8 +96,11 @@ void ubi_dbg_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len);
 
 #ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
 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);
 #else
 #define ubi_dbg_check_all_ff(ubi, pnum, offset, len) 0
+#define ubi_dbg_check_write(ubi, buf, pnum, offset, len) 0
 #endif
 
 #ifdef CONFIG_MTD_UBI_DEBUG_DISABLE_BGT
@@ -176,6 +179,7 @@ static inline int ubi_dbg_is_erase_failure(void)
 #define ubi_dbg_is_write_failure() 0
 #define ubi_dbg_is_erase_failure() 0
 #define ubi_dbg_check_all_ff(ubi, pnum, offset, len) 0
+#define ubi_dbg_check_write(ubi, buf, pnum, offset, len) 0
 
 #endif /* !CONFIG_MTD_UBI_DEBUG */
 #endif /* !__UBI_DEBUG_H__ */
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index a2501299a67c..b4ecc84c7549 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -273,6 +273,21 @@ int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
         } else
                 ubi_assert(written == len);
 
+        if (!err) {
+                err = ubi_dbg_check_write(ubi, buf, pnum, offset, len);
+                if (err)
+                        return err;
+
+                /*
+                 * Since we always write sequentially, the rest of the PEB has
+                 * to contain only 0xFF bytes.
+                 */
+                offset += len;
+                len = ubi->peb_size - offset;
+                if (len)
+                        err = ubi_dbg_check_all_ff(ubi, pnum, offset, len);
+        }
+
         return err;
 }
 
@@ -1282,6 +1297,61 @@ exit:
 }
 
 /**
+ * ubi_dbg_check_write - make sure write succeeded.
+ * @ubi: UBI device description object
+ * @buf: buffer with data which were written
+ * @pnum: physical eraseblock number the data were written to
+ * @offset: offset within the physical eraseblock the data were written to
+ * @len: how many bytes were written
+ *
+ * This functions reads data which were recently written and compares it with
+ * the original data buffer - the data have to match. Returns zero if the data
+ * match and a negative error code if not or in case of failure.
+ */
+int ubi_dbg_check_write(struct ubi_device *ubi, const void *buf, int pnum,
+                        int offset, int len)
+{
+        int err, i;
+
+        mutex_lock(&ubi->dbg_buf_mutex);
+        err = ubi_io_read(ubi, ubi->dbg_peb_buf, pnum, offset, len);
+        if (err)
+                goto out_unlock;
+
+        for (i = 0; i < len; i++) {
+                uint8_t c = ((uint8_t *)buf)[i];
+                uint8_t c1 = ((uint8_t *)ubi->dbg_peb_buf)[i];
+                int dump_len;
+
+                if (c == c1)
+                        continue;
+
+                ubi_err("paranoid check failed for PEB %d:%d, len %d",
+                        pnum, offset, len);
+                ubi_msg("data differ at position %d", i);
+                dump_len = max_t(int, 128, len - i);
+                ubi_msg("hex dump of the original buffer from %d to %d",
+                        i, i + dump_len);
+                print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+                               buf + i, dump_len, 1);
+                ubi_msg("hex dump of the read buffer from %d to %d",
+                        i, i + dump_len);
+                print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+                               ubi->dbg_peb_buf + i, dump_len, 1);
+                ubi_dbg_dump_stack();
+                err = -EINVAL;
+                goto out_unlock;
+        }
+        mutex_unlock(&ubi->dbg_buf_mutex);
+
+        return 0;
+
+out_unlock:
+        mutex_unlock(&ubi->dbg_buf_mutex);
+        return err;
+}
+
+/**
  * ubi_dbg_check_all_ff - check that a region of flash is empty.
  * @ubi: UBI device description object
  * @pnum: the physical eraseblock number to check