mtd: cfi: cmdset_0002: Do not allow read/write to suspend erase block.

BugLink: http://bugs.launchpad.net/bugs/1768825

commit 7b70eb14 upstream.

Currently it is possible to read and/or write to suspend EB's.
Writing /dev/mtdX or /dev/mtdblockX from several processes may
break the flash state machine.

Taken from cfi_cmdset_0001 driver.
Signed-off-by: Joakim Tjernlund <joakim.tjernlund@infinera.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/mtd/chips/cfi_cmdset_0002.c

@@ -814,9 +814,10 @@ static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr
 		    (mode == FL_WRITING && (cfip->EraseSuspend & 0x2))))
 			goto sleep;
 
-		/* We could check to see if we're trying to access the sector
-		 * that is currently being erased. However, no user will try
-		 * anything like that so we just wait for the timeout. */
+		/* Do not allow suspend iff read/write to EB address */
+		if ((adr & chip->in_progress_block_mask) ==
+		    chip->in_progress_block_addr)
+			goto sleep;
 
 		/* Erase suspend */
 		/* It's harmless to issue the Erase-Suspend and Erase-Resume
@@ -2265,6 +2266,7 @@ static int __xipram do_erase_chip(struct map_info *map, struct flchip *chip)
 	chip->state = FL_ERASING;
 	chip->erase_suspended = 0;
 	chip->in_progress_block_addr = adr;
+	chip->in_progress_block_mask = ~(map->size - 1);
 
 	INVALIDATE_CACHE_UDELAY(map, chip,
 				adr, map->size,
@@ -2354,6 +2356,7 @@ static int __xipram do_erase_oneblock(struct map_info *map, struct flchip *chip,
 	chip->state = FL_ERASING;
 	chip->erase_suspended = 0;
 	chip->in_progress_block_addr = adr;
+	chip->in_progress_block_mask = ~(len - 1);
 
 	INVALIDATE_CACHE_UDELAY(map, chip,
 				adr, len,