From: Richard Weinberger <richard@nod.at>
Date: Fri, 19 Sep 2014 15:37:56 +0000 (+0200)
Subject: UBI: Fix livelock in produce_free_peb()
X-Git-Tag: firefly_0821_release~176^2~3039^2~6
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=b91671bb23a79c32a23b0ad5d6e6ad292bb21bdf;p=firefly-linux-kernel-4.4.55.git

UBI: Fix livelock in produce_free_peb()

The while loop in produce_free_peb() assumes that each work will produce a
free PEB. This is not true.
If ubi->works_count is 1 and the only scheduled work is the
wear_leveling_worker() produce_free_peb() can loop forever in case
nobody schedules an erase work.
Fix this issue by checking in the while loop whether work is scheduled.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
---

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 20f491713145..32b3c1486a05 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -272,7 +272,7 @@ static int produce_free_peb(struct ubi_device *ubi)
 {
 	int err;
 
-	while (!ubi->free.rb_node) {
+	while (!ubi->free.rb_node && ubi->works_count) {
 		spin_unlock(&ubi->wl_lock);
 
 		dbg_wl("do one work synchronously");