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| author | Alexander Gordeev <agordeev@redhat.com> | 2015-06-03 08:18:27 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-07-15 14:45:16 -0700 |
| commit | a6d77081e266605c9f4d8c11e0ee00468b9dc614 (patch) | |
| tree | b9f200361754e95386e1464a6e21ee1346fb0e82 /kernel/rcu/tree.h | |
| parent | 9618138b09260e3df5af5a0d7bdc8fca010f6a3f (diff) | |
| download | blackbird-op-linux-a6d77081e266605c9f4d8c11e0ee00468b9dc614.tar.gz blackbird-op-linux-a6d77081e266605c9f4d8c11e0ee00468b9dc614.zip | |
rcu: Limit rcu_state::levelcnt[] to RCU_NUM_LVLS items
Variable rcu_num_lvls is limited by RCU_NUM_LVLS macro.
In turn, rcu_state::levelcnt[] array is never accessed
beyond rcu_num_lvls. Thus, rcu_state::levelcnt[] is safe
to limit to RCU_NUM_LVLS items.
Since rcu_num_lvls could be changed during boot (as result
of rcutree.rcu_fanout_leaf kernel parameter update) one might
assume a new value could overflow the value of RCU_NUM_LVLS.
However, that is not the case, since leaf-level fanout is only
permitted to increase, resulting in rcu_num_lvls possibly to
decrease.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree.h')
| -rw-r--r-- | kernel/rcu/tree.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index f1f4784f9107..a6faae53ea8f 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -443,7 +443,7 @@ do { \ struct rcu_state { struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */ struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */ - u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */ + u32 levelcnt[RCU_NUM_LVLS]; /* # nodes in each level. */ u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */ u8 flavor_mask; /* bit in flavor mask. */ struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */ |
