Commit-ID: 49e291266d0920264471d9d64268fb030e33a99a Gitweb: http://git.kernel.org/tip/49e291266d0920264471d9d64268fb030e33a99a Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> AuthorDate: Fri, 18 Sep 2009 09:50:19 -0700 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Sat, 19 Sep 2009 08:53:21 +0200 rcu: Fix thinko, actually initialize full tree Commit de078d8 ("rcu: Need to update rnp->gpnum if preemptable RCU is to be reliable") repeatedly and incorrectly initializes the root rcu_node structure's ->gpnum field rather than initializing the ->gpnum field of each node in the tree. Fix this. Also add an additional consistency check to catch this in the future. Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Cc: laijs@xxxxxxxxxxxxxx Cc: dipankar@xxxxxxxxxx Cc: akpm@xxxxxxxxxxxxxxxxxxxx Cc: mathieu.desnoyers@xxxxxxxxxx Cc: josh@xxxxxxxxxxxxxxxx Cc: dvhltc@xxxxxxxxxx Cc: niv@xxxxxxxxxx Cc: peterz@xxxxxxxxxxxxx Cc: rostedt@xxxxxxxxxxx Cc: Valdis.Kletnieks@xxxxxx LKML-Reference: <125329262011-git-send-email-> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/rcutree.c | 11 ++++------- kernel/rcutree_plugin.h | 4 +++- 2 files changed, 7 insertions(+), 8 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index ae4a553..1b32cdd 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -601,8 +601,6 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) { struct rcu_data *rdp = rsp->rda[smp_processor_id()]; struct rcu_node *rnp = rcu_get_root(rsp); - struct rcu_node *rnp_cur; - struct rcu_node *rnp_end; if (!cpu_needs_another_gp(rsp, rdp)) { spin_unlock_irqrestore(&rnp->lock, flags); @@ -659,13 +657,12 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) * one corresponding to this CPU, due to the fact that we have * irqs disabled. */ - rnp_end = &rsp->node[NUM_RCU_NODES]; - for (rnp_cur = &rsp->node[0]; rnp_cur < rnp_end; rnp_cur++) { - spin_lock(&rnp_cur->lock); /* irqs already disabled. */ + for (rnp = &rsp->node[0]; rnp < &rsp->node[NUM_RCU_NODES]; rnp++) { + spin_lock(&rnp->lock); /* irqs already disabled. */ rcu_preempt_check_blocked_tasks(rnp); - rnp_cur->qsmask = rnp_cur->qsmaskinit; + rnp->qsmask = rnp->qsmaskinit; rnp->gpnum = rsp->gpnum; - spin_unlock(&rnp_cur->lock); /* irqs already disabled. */ + spin_unlock(&rnp->lock); /* irqs already disabled. */ } rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index cd6047c..09b7325 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -476,10 +476,12 @@ static void rcu_print_task_stall(struct rcu_node *rnp) /* * Because there is no preemptable RCU, there can be no readers blocked, - * so there is no need to check for blocked tasks. + * so there is no need to check for blocked tasks. So check only for + * bogus qsmask values. */ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) { + WARN_ON_ONCE(rnp->qsmask); } /* -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html