linux-kernel - [PATCH 6/7] UBI: Fastmap: Make sure that find_wl

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Date:	Mon,  9 Jul 2012 14:18:42 +0200
From:	Richard Weinberger <richard@....at>
To:	linux-mtd@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org, adrian.hunter@...el.com,
	Heinz.Egger@...utronix.de, thomas.wucher@...utronix.de,
	shmulik.ladkani@...il.com, tglx@...utronix.de,
	tim.bird@...sony.com, Marius.Mazarel@...l.ro,
	artem.bityutskiy@...ux.intel.com, nyoushchenko@...sta.com,
	Richard Weinberger <richard@....at>
Subject: [PATCH 6/7] UBI: Fastmap: Make sure that find_wl_entry() never returns NULL

If the rbtree contains only one entry and we don't have fastmap
on flash find_wl_entry() might return NULL.
This must not happen.

Signed-off-by: Richard Weinberger <richard@....at>
---
 drivers/mtd/ubi/wl.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 79e3257..d61672d 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -376,7 +376,8 @@ static struct ubi_wl_entry *find_wl_entry(struct ubi_device *ubi,
 	/* If no fastmap has been written and this WL entry can be used
 	 * as anchor PEB, hold it back and return the second best WL entry
 	 * such that fastmap can use the anchor PEB later. */
-	if (!ubi->fm_disabled && !ubi->fm && e->pnum < UBI_FM_MAX_START)
+	if (prev_e && !ubi->fm_disabled &&
+	    !ubi->fm && e->pnum < UBI_FM_MAX_START)
 		return prev_e;
 
 	return e;
-- 
1.7.6.5

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