Dept already prevents creating dependencies between different depths of
the class indicated by *_lock_nested() when the lock acquisitions happen
consecutively.
lock A0 with depth
lock_nested A1 with depth + 1
...
unlock A1
unlock A0
Dept does not create A0 -> A1 dependency in this case, either.
However, once another class cut in, the code becomes problematic. When
Dept tries to create real dependencies, it does not only create real
ones but also wrong ones between different depths of the class.
lock A0 with depth
lock B
lock_nested A1 with depth + 1
...
unlock A1
unlock B
unlock A0
Even in this case, Dept should not create A0 -> A1 dependency.
So let Dept not create wrong dependencies between different depths of
the class in any case.
Reported-by: 42.hyeyoo@xxxxxxxxx
Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
---
kernel/dependency/dept.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/kernel/dependency/dept.c b/kernel/dependency/dept.c
index 5d4efc3..cc1b3a3 100644
--- a/kernel/dependency/dept.c
+++ b/kernel/dependency/dept.c
@@ -1458,14 +1458,7 @@ static void add_wait(struct dept_class *c, unsigned long ip,
eh = dt->ecxt_held + i;
if (eh->ecxt->class != c || eh->nest == ne)
- break;
- }
-
- for (; i >= 0; i--) {
- struct dept_ecxt_held *eh;
-
- eh = dt->ecxt_held + i;
- add_dep(eh->ecxt, w);
+ add_dep(eh->ecxt, w);
}
if (!wait_consumed(w) && !rich_stack) {
--
1.9.1
