Merge branch 'linux-next' of git://git.infradead.org/ubi-2.6

* 'linux-next' of git://git.infradead.org/ubi-2.6:
  UBI: improve NOR flash erasure quirk
  UBI: introduce flash dump helper
  UBI: eliminate possible undefined behaviour
  UBI: print a warning if too many PEBs are corrupted
  UBI: amend NOR flash pre-erase quirk
  UBI: print a message if ECH is corrupted and VIDH is ok

drivers/mtd/ubi/debug.c

@@ -196,4 +196,36 @@ void ubi_dbg_dump_mkvol_req(const struct ubi_mkvol_req *req)
 	printk(KERN_DEBUG "\t1st 16 characters of name: %s\n", nm);
 }
 
+/**
+ * ubi_dbg_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_dbg_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 = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
+	if (err && err != -EUCLEAN) {
+		ubi_err("error %d while reading %d bytes from PEB %d:%d, "
+			"read %zd bytes", err, len, pnum, offset, read);
+		goto out;
+	}
+
+	dbg_msg("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;
+}
+
 #endif /* CONFIG_MTD_UBI_DEBUG */

drivers/mtd/ubi/debug.h

@@ -55,6 +55,7 @@ void ubi_dbg_dump_vtbl_record(const struct ubi_vtbl_record *r, int idx);
 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);
 
 #ifdef CONFIG_MTD_UBI_DEBUG_MSG
 /* General debugging messages */
@@ -167,6 +168,7 @@ static inline int ubi_dbg_is_erase_failure(void)
 #define ubi_dbg_dump_sv(sv)              ({})
 #define ubi_dbg_dump_seb(seb, type)      ({})
 #define ubi_dbg_dump_mkvol_req(req)      ({})
+#define ubi_dbg_dump_flash(ubi, pnum, offset, len) ({})
 
 #define UBI_IO_DEBUG               0
 #define DBG_DISABLE_BGT            0

drivers/mtd/ubi/io.c

@@ -269,6 +269,7 @@ int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
 		ubi_err("error %d while writing %d bytes to PEB %d:%d, written "
 			"%zd bytes", err, len, pnum, offset, written);
 		ubi_dbg_dump_stack();
+		ubi_dbg_dump_flash(ubi, pnum, offset, len);
 	} else
 		ubi_assert(written == len);
 
@@ -475,30 +476,46 @@ out:
  */
 static int nor_erase_prepare(struct ubi_device *ubi, int pnum)
 {
-	int err;
+	int err, err1;
 	size_t written;
 	loff_t addr;
 	uint32_t data = 0;
+	struct ubi_vid_hdr vid_hdr;
 
-	addr = (loff_t)pnum * ubi->peb_size;
+	addr = (loff_t)pnum * ubi->peb_size + ubi->vid_hdr_aloffset;
 	err = ubi->mtd->write(ubi->mtd, addr, 4, &written, (void *)&data);
-	if (err) {
-		ubi_err("error %d while writing 4 bytes to PEB %d:%d, written "
-			"%zd bytes", err, pnum, 0, written);
-		ubi_dbg_dump_stack();
-		return err;
+	if (!err) {
+		addr -= ubi->vid_hdr_aloffset;
+		err = ubi->mtd->write(ubi->mtd, addr, 4, &written,
+				      (void *)&data);
+		if (!err)
+			return 0;
 	}
 
-	addr += ubi->vid_hdr_aloffset;
-	err = ubi->mtd->write(ubi->mtd, addr, 4, &written, (void *)&data);
-	if (err) {
-		ubi_err("error %d while writing 4 bytes to PEB %d:%d, written "
-			"%zd bytes", err, pnum, ubi->vid_hdr_aloffset, written);
-		ubi_dbg_dump_stack();
-		return err;
-	}
+	/*
+	 * We failed to write to the media. This was observed with Spansion
+	 * S29GL512N NOR flash. Most probably the eraseblock erasure was
+	 * interrupted at a very inappropriate moment, so it became unwritable.
+	 * In this case we probably anyway have garbage in this PEB.
+	 */
+	err1 = ubi_io_read_vid_hdr(ubi, pnum, &vid_hdr, 0);
+	if (err1 == UBI_IO_BAD_VID_HDR)
+		/*
+		 * The VID header is corrupted, so we can safely erase this
+		 * PEB and not afraid that it will be treated as a valid PEB in
+		 * case of an unclean reboot.
+		 */
+		return 0;
 
-	return 0;
+	/*
+	 * The PEB contains a valid VID header, but we cannot invalidate it.
+	 * Supposedly the flash media or the driver is screwed up, so return an
+	 * error.
+	 */
+	ubi_err("cannot invalidate PEB %d, write returned %d read returned %d",
+		pnum, err, err1);
+	ubi_dbg_dump_flash(ubi, pnum, 0, ubi->peb_size);
+	return -EIO;
 }
 
 /**

drivers/mtd/ubi/scan.c

@@ -75,9 +75,10 @@ static int add_to_list(struct ubi_scan_info *si, int pnum, int ec,
 		dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
 	else if (list == &si->erase)
 		dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
-	else if (list == &si->corr)
+	else if (list == &si->corr) {
 		dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
-	else if (list == &si->alien)
+		si->corr_count += 1;
+	} else if (list == &si->alien)
 		dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
 	else
 		BUG();
@@ -864,7 +865,9 @@ static int process_eb(struct ubi_device *ubi, struct ubi_scan_info *si,
 		}
 	}
 
-	/* Both UBI headers seem to be fine */
+	if (ec_corr)
+		ubi_warn("valid VID header but corrupted EC header at PEB %d",
+			 pnum);
 	err = ubi_scan_add_used(ubi, si, pnum, ec, vidh, bitflips);
 	if (err)
 		return err;
@@ -935,6 +938,19 @@ struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
 	if (si->is_empty)
 		ubi_msg("empty MTD device detected");
 
+	/*
+	 * Few corrupted PEBs are not a problem and may be just a result of
+	 * unclean reboots. However, many of them may indicate some problems
+	 * with the flash HW or driver. Print a warning in this case.
+	 */
+	if (si->corr_count >= 8 || si->corr_count >= ubi->peb_count / 4) {
+		ubi_warn("%d PEBs are corrupted", si->corr_count);
+		printk(KERN_WARNING "corrupted PEBs are:");
+		list_for_each_entry(seb, &si->corr, u.list)
+			printk(KERN_CONT " %d", seb->pnum);
+		printk(KERN_CONT "\n");
+	}
+
 	/*
 	 * In case of unknown erase counter we use the mean erase counter
 	 * value.

drivers/mtd/ubi/scan.h

@@ -102,6 +102,7 @@ struct ubi_scan_volume {
  * @mean_ec: mean erase counter value
  * @ec_sum: a temporary variable used when calculating @mean_ec
  * @ec_count: a temporary variable used when calculating @mean_ec
+ * @corr_count: count of corrupted PEBs
  * @image_seq_set: indicates @ubi->image_seq is known
  *
  * This data structure contains the result of scanning and may be used by other
@@ -125,6 +126,7 @@ struct ubi_scan_info {
 	int mean_ec;
 	uint64_t ec_sum;
 	int ec_count;
+	int corr_count;
 	int image_seq_set;
 };
 

drivers/mtd/ubi/ubi.h

@@ -579,7 +579,8 @@ void ubi_do_get_volume_info(struct ubi_device *ubi, struct ubi_volume *vol,
 	for (rb = rb_first(root),                                            \
 	     pos = (rb ? container_of(rb, typeof(*pos), member) : NULL);     \
 	     rb;                                                             \
-	     rb = rb_next(rb), pos = container_of(rb, typeof(*pos), member))
+	     rb = rb_next(rb),                                               \
+	     pos = (rb ? container_of(rb, typeof(*pos), member) : NULL))
 
 /**
  * ubi_zalloc_vid_hdr - allocate a volume identifier header object.