Messages in this thread | | | Date | Tue, 15 Dec 2009 17:59:54 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH RFC tip/core/rcu 15/18] rcu: give different levels of the rcu_node hierarchy distinct lockdep names |
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On Tue, Dec 15, 2009 at 04:59:59PM -0800, Josh Triplett wrote: > On Tue, Dec 15, 2009 at 03:02:38PM -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! */ > > + > > BUILD_BUG_ON seems better. For that matter, please consider moving > these near the rest of the level-specific defines, making them const, > and ideally not emitting the strings for levels you don't have.
Good point, I had forgotten about BUILD_BUG_ON(). And reviewing its definition, I can see why one might be motivated to forget. ;-)
The reason I put the definition of buf[] here and the reason that I am not worried about the memory it consumes is that this is an __init function, so its memory should be reused once the system boots. And if __init does not apply to the static variables in a function, it should! ;-)
Thanx, Paul
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