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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2009-09-18 09:50:19 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-09-19 08:53:21 +0200 |
| commit | 49e291266d0920264471d9d64268fb030e33a99a (patch) | |
| tree | 8770717427ee877e6b7b3dae6b120f35be645d70 /kernel | |
| parent | e7d8842ed34a7fe19d1ed90f84c211fb056ac523 (diff) | |
| download | linux-49e291266d0920264471d9d64268fb030e33a99a.tar.gz linux-49e291266d0920264471d9d64268fb030e33a99a.tar.bz2 linux-49e291266d0920264471d9d64268fb030e33a99a.zip | |
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@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
LKML-Reference: <125329262011-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcutree.c | 11 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 4 |
2 files changed, 7 insertions, 8 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index ae4a553e37ce..1b32cdd1b2e2 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 cd6047cc7fc2..09b7325baad1 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); } /* |