sched/preempt, sh: kmap_coherent relies on disabled preemption

David Hildenbrand · Rich Felker · commit b15d53d00955 · 2016-03-17T19:46:14.000Z
kmap_coherent needs disabled preemption to not schedule in the critical section, just like kmap_coherent on mips and kmap_atomic in general. Fixes: 8222dbe "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>
diff --git 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();
 }

Original file line number	Diff line number	Diff line change
`@@ -36,6 +36,7 @@ void kmap_coherent(struct page page, unsigned long addr)`
`36`	`36`
`37`	`37`	`BUG_ON(!test_bit(PG_dcache_clean, &page->flags));`
`38`	`38`
	`39`	`+ preempt_disable();`
`39`	`40`	`pagefault_disable();`
`40`	`41`
`41`	`42`	`idx = FIX_CMAP_END -`
`@@ -64,4 +65,5 @@ void kunmap_coherent(void *kvaddr)`
`64`	`65`	`}`
`65`	`66`
`66`	`67`	`pagefault_enable();`
	`68`	`+ preempt_enable();`
`67`	`69`	`}`