From ea9b0c8a26a2cadfe49382d679eee88d3c4de79c Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 28 Apr 2017 13:19:28 -0700 Subject: [PATCH] rcu: Add lockdep_assert_held() teeth to tree_plugin.h Comments can be helpful, but assertions carry more force. This commit therefore adds lockdep_assert_held() and RCU_LOCKDEP_WARN() calls to enforce lock-held and interrupt-disabled preconditions. Reported-by: Peter Zijlstra Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_plugin.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 9cb3dff78b6f..ee7cea75273e 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -181,6 +181,8 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp) (rnp->expmask & rdp->grpmask ? RCU_EXP_BLKD : 0); struct task_struct *t = current; + lockdep_assert_held(&rnp->lock); + /* * Decide where to queue the newly blocked task. In theory, * this could be an if-statement. In practice, when I tried @@ -289,6 +291,7 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp) */ static void rcu_preempt_qs(void) { + RCU_LOCKDEP_WARN(preemptible(), "rcu_preempt_qs() invoked with preemption enabled!!!\n"); if (__this_cpu_read(rcu_data_p->cpu_no_qs.s)) { trace_rcu_grace_period(TPS("rcu_preempt"), __this_cpu_read(rcu_data_p->gpnum), @@ -318,6 +321,7 @@ static void rcu_preempt_note_context_switch(bool preempt) struct rcu_data *rdp; struct rcu_node *rnp; + RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_preempt_note_context_switch() invoked with interrupts enabled!!!\n"); WARN_ON_ONCE(!preempt && t->rcu_read_lock_nesting > 0); if (t->rcu_read_lock_nesting > 0 && !t->rcu_read_unlock_special.b.blocked) { @@ -634,6 +638,7 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp) */ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) { + RCU_LOCKDEP_WARN(preemptible(), "rcu_preempt_check_blocked_tasks() invoked with preemption enabled!!!\n"); WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp)); if (rcu_preempt_has_tasks(rnp)) rnp->gp_tasks = rnp->blkd_tasks.next; @@ -1024,6 +1029,7 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags) { struct task_struct *t; + lockdep_assert_held(&rnp->lock); if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL) { rnp->n_balk_exp_gp_tasks++; raw_spin_unlock_irqrestore_rcu_node(rnp, flags); @@ -1404,6 +1410,7 @@ int rcu_needs_cpu(u64 basemono, u64 *nextevt) struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks); unsigned long dj; + RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_needs_cpu() invoked with irqs enabled!!!"); if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL)) { *nextevt = KTIME_MAX; return 0; @@ -1456,6 +1463,7 @@ static void rcu_prepare_for_idle(void) struct rcu_state *rsp; int tne; + RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_prepare_for_idle() invoked with irqs enabled!!!"); if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL) || rcu_is_nocb_cpu(smp_processor_id())) return; @@ -1511,6 +1519,7 @@ static void rcu_prepare_for_idle(void) */ static void rcu_cleanup_after_idle(void) { + RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_cleanup_after_idle() invoked with irqs enabled!!!"); if (IS_ENABLED(CONFIG_RCU_NOCB_CPU_ALL) || rcu_is_nocb_cpu(smp_processor_id())) return; @@ -2544,6 +2553,8 @@ static void rcu_sysidle_enter(int irq) unsigned long j; struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks); + RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_sysidle_enter() invoked with irqs enabled!!!"); + /* If there are no nohz_full= CPUs, no need to track this. */ if (!tick_nohz_full_enabled()) return; @@ -2615,6 +2626,8 @@ static void rcu_sysidle_exit(int irq) { struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks); + RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_sysidle_exit() invoked with irqs enabled!!!"); + /* If there are no nohz_full= CPUs, no need to track this. */ if (!tick_nohz_full_enabled()) return; @@ -2674,6 +2687,8 @@ static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle, unsigned long j; struct rcu_dynticks *rdtp = rdp->dynticks; + RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_sysidle_check_cpu() invoked with irqs enabled!!!"); + /* If there are no nohz_full= CPUs, don't check system-wide idleness. */ if (!tick_nohz_full_enabled()) return; @@ -2842,6 +2857,8 @@ bool rcu_sys_is_idle(void) static struct rcu_sysidle_head rsh; int rss = READ_ONCE(full_sysidle_state); + RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_sys_is_idle() invoked with irqs enabled!!!"); + if (WARN_ON_ONCE(smp_processor_id() != tick_do_timer_cpu)) return false; -- 2.39.5