mtd: nand: omap: fix race condition in omap_wait()

If a context switch occurs in function omap_wait() just before the
while loop is entered, then upon return from context switch the
timeout may already have elapsed: in that case, status is never
read from NAND device, and omap_wait() returns an error.
This failure has been experimentally observed during stress tests.

This patch ensures a NAND status read is always performed before
returning, as in the generic nand_wait() function.

Signed-off-by: Ivan Djelic <ivan.djelic@parrot.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/omap2.c

@@ -881,7 +881,7 @@ static int omap_wait(struct mtd_info *mtd, struct nand_chip *chip)
 	struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
 							mtd);
 	unsigned long timeo = jiffies;
-	int status = NAND_STATUS_FAIL, state = this->state;
+	int status, state = this->state;
 
 	if (state == FL_ERASING)
 		timeo += (HZ * 400) / 1000;
@@ -896,6 +896,8 @@ static int omap_wait(struct mtd_info *mtd, struct nand_chip *chip)
 			break;
 		cond_resched();
 	}
+
+	status = gpmc_nand_read(info->gpmc_cs, GPMC_NAND_DATA);
 	return status;
 }