linux-kernel - [PATCH] UBI: Fix livelock in produce_free

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Message-Id: <1411141076-21489-1-git-send-email-richard@nod.at>
Date:	Fri, 19 Sep 2014 17:37:56 +0200
From:	Richard Weinberger <richard@....at>
To:	dedekind1@...il.com
Cc:	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Richard Weinberger <richard@....at>
Subject: [PATCH] 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@....at>
---
 drivers/mtd/ubi/wl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 0509c8a..6add739 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");
-- 
1.8.4.5

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