Messages in this thread | | | Subject | Re: [PATCH RFC tip/core/rcu 15/18] rcu: give different levels of the rcu_node hierarchy distinct lockdep names | From | Peter Zijlstra <> | Date | Wed, 16 Dec 2009 11:26:00 +0100 |
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On Tue, 2009-12-15 at 15:02 -0800, Paul E. McKenney wrote: > From: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > Proposed for 2.6.34, not for inclusion. > > Previously, each level of the rcu_node hierarchy had the same rather > unimaginative name: "&rcu_node_class[i]". This makes lockdep diagnostics > involving these lockdep classes less helpful than would be nice. This > patch fixes this by giving each level of the rcu_node hierarchy a distinct > name: "rcu_node_level_0", "rcu_node_level_1", and so on. > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > --- > kernel/rcutree.c | 9 ++++++++- > 1 files changed, 8 insertions(+), 1 deletions(-) > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > index 0a4c328..a6e45f6 100644 > --- a/kernel/rcutree.c > +++ b/kernel/rcutree.c > @@ -1811,11 +1811,17 @@ static void __init rcu_init_levelspread(struct rcu_state *rsp) > */ > static void __init rcu_init_one(struct rcu_state *rsp) > { > + static char *buf[] = { "rcu_node_level_0", > + "rcu_node_level_1", > + "rcu_node_level_2", > + "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */ > int cpustride = 1; > int i; > int j; > struct rcu_node *rnp; > > + WARN_ON_ONCE(MAX_RCU_LVLS > 4); /* Fix buf[] initialization! */
So you're going to WARN here,
> /* Initialize the level-tracking arrays. */ > > for (i = 1; i < NUM_RCU_LVLS; i++) > @@ -1829,7 +1835,8 @@ static void __init rcu_init_one(struct rcu_state *rsp) > rnp = rsp->level[i]; > for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) { > spin_lock_init(&rnp->lock); > - lockdep_set_class(&rnp->lock, &rcu_node_class[i]); > + lockdep_set_class_and_name(&rnp->lock, > + &rcu_node_class[i], buf[i]);
and segfault here because i overruns its bounds?
Might as well BUG_ON then.
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