From: David Hildenbrand <dahi@linux.vnet.ibm.com>
Date: Mon, 29 Feb 2016 08:19:24 +0000 (+0100)
Subject: sched/preempt, sh: kmap_coherent relies on disabled preemption
X-Git-Tag: firefly_0821_release~176^2~4^2~50^2~186
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=10595c57f4682b096d6ac6dd2212ac889f08d9f4;p=firefly-linux-kernel-4.4.55.git

sched/preempt, sh: kmap_coherent relies on disabled preemption

commit b15d53d009558d14c4f394a6d1fa2039c7f45c43 upstream.

kmap_coherent needs disabled preemption to not schedule in the critical
section, just like kmap_coherent on mips and kmap_atomic in general.

Fixes: 8222dbe21e79 "sched/preempt, mm/fault: Decouple preemption from the page fault logic"
Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Rich Felker <dalias@libc.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/sh/mm/kmap.c b/arch/sh/mm/kmap.c
index ec29e14ec5a8..bf25d7c79a2d 100644
--- a/arch/sh/mm/kmap.c
+++ b/arch/sh/mm/kmap.c
@@ -36,6 +36,7 @@ void *kmap_coherent(struct page *page, unsigned long addr)
 
 	BUG_ON(!test_bit(PG_dcache_clean, &page->flags));
 
+	preempt_disable();
 	pagefault_disable();
 
 	idx = FIX_CMAP_END -
@@ -64,4 +65,5 @@ void kunmap_coherent(void *kvaddr)
 	}
 
 	pagefault_enable();
+	preempt_enable();
 }