diff options
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/rcuperf.c | 7 | ||||
| -rw-r--r-- | kernel/rcu/rcutorture.c | 62 | ||||
| -rw-r--r-- | kernel/rcu/tree.c | 32 | ||||
| -rw-r--r-- | kernel/rcu/tree.h | 1 | ||||
| -rw-r--r-- | kernel/rcu/tree_exp.h | 124 | ||||
| -rw-r--r-- | kernel/rcu/tree_trace.c | 7 |
6 files changed, 135 insertions, 98 deletions
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c index d38ab08a3fe7..123ccbd22449 100644 --- a/kernel/rcu/rcuperf.c +++ b/kernel/rcu/rcuperf.c @@ -52,7 +52,7 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>"); #define PERF_FLAG "-perf:" #define PERFOUT_STRING(s) \ - pr_alert("%s" PERF_FLAG s "\n", perf_type) + pr_alert("%s" PERF_FLAG " %s\n", perf_type, s) #define VERBOSE_PERFOUT_STRING(s) \ do { if (verbose) pr_alert("%s" PERF_FLAG " %s\n", perf_type, s); } while (0) #define VERBOSE_PERFOUT_ERRSTRING(s) \ @@ -400,9 +400,8 @@ rcu_perf_writer(void *arg) sp.sched_priority = 0; sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp); - pr_alert("%s" PERF_FLAG - "rcu_perf_writer %ld has %d measurements\n", - perf_type, me, MIN_MEAS); + pr_alert("%s%s rcu_perf_writer %ld has %d measurements\n", + perf_type, PERF_FLAG, me, MIN_MEAS); if (atomic_inc_return(&n_rcu_perf_writer_finished) >= nrealwriters) { schedule_timeout_interruptible(10); diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 971e2b138063..bf08fee53dc7 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1238,6 +1238,7 @@ rcu_torture_stats_print(void) long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; static unsigned long rtcv_snap = ULONG_MAX; + struct task_struct *wtp; for_each_possible_cpu(cpu) { for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { @@ -1258,8 +1259,9 @@ rcu_torture_stats_print(void) atomic_read(&n_rcu_torture_alloc), atomic_read(&n_rcu_torture_alloc_fail), atomic_read(&n_rcu_torture_free)); - pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ", + pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ", atomic_read(&n_rcu_torture_mberror), + n_rcu_torture_barrier_error, n_rcu_torture_boost_ktrerror, n_rcu_torture_boost_rterror); pr_cont("rtbf: %ld rtb: %ld nt: %ld ", @@ -1312,10 +1314,12 @@ rcu_torture_stats_print(void) rcutorture_get_gp_data(cur_ops->ttype, &flags, &gpnum, &completed); - pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x\n", + wtp = READ_ONCE(writer_task); + pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx\n", rcu_torture_writer_state_getname(), rcu_torture_writer_state, - gpnum, completed, flags); + gpnum, completed, flags, + wtp == NULL ? ~0UL : wtp->state); show_rcu_gp_kthreads(); rcu_ftrace_dump(DUMP_ALL); } @@ -1362,12 +1366,12 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag) onoff_interval, onoff_holdoff); } -static void rcutorture_booster_cleanup(int cpu) +static int rcutorture_booster_cleanup(unsigned int cpu) { struct task_struct *t; if (boost_tasks[cpu] == NULL) - return; + return 0; mutex_lock(&boost_mutex); t = boost_tasks[cpu]; boost_tasks[cpu] = NULL; @@ -1375,9 +1379,10 @@ static void rcutorture_booster_cleanup(int cpu) /* This must be outside of the mutex, otherwise deadlock! */ torture_stop_kthread(rcu_torture_boost, t); + return 0; } -static int rcutorture_booster_init(int cpu) +static int rcutorture_booster_init(unsigned int cpu) { int retval; @@ -1577,28 +1582,7 @@ static void rcu_torture_barrier_cleanup(void) } } -static int rcutorture_cpu_notify(struct notifier_block *self, - unsigned long action, void *hcpu) -{ - long cpu = (long)hcpu; - - switch (action & ~CPU_TASKS_FROZEN) { - case CPU_ONLINE: - case CPU_DOWN_FAILED: - (void)rcutorture_booster_init(cpu); - break; - case CPU_DOWN_PREPARE: - rcutorture_booster_cleanup(cpu); - break; - default: - break; - } - return NOTIFY_OK; -} - -static struct notifier_block rcutorture_cpu_nb = { - .notifier_call = rcutorture_cpu_notify, -}; +static enum cpuhp_state rcutor_hp; static void rcu_torture_cleanup(void) @@ -1638,11 +1622,8 @@ rcu_torture_cleanup(void) for (i = 0; i < ncbflooders; i++) torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]); if ((test_boost == 1 && cur_ops->can_boost) || - test_boost == 2) { - unregister_cpu_notifier(&rcutorture_cpu_nb); - for_each_possible_cpu(i) - rcutorture_booster_cleanup(i); - } + test_boost == 2) + cpuhp_remove_state(rcutor_hp); /* * Wait for all RCU callbacks to fire, then do flavor-specific @@ -1869,14 +1850,13 @@ rcu_torture_init(void) test_boost == 2) { boost_starttime = jiffies + test_boost_interval * HZ; - register_cpu_notifier(&rcutorture_cpu_nb); - for_each_possible_cpu(i) { - if (cpu_is_offline(i)) - continue; /* Heuristic: CPU can go offline. */ - firsterr = rcutorture_booster_init(i); - if (firsterr) - goto unwind; - } + + firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE", + rcutorture_booster_init, + rcutorture_booster_cleanup); + if (firsterr < 0) + goto unwind; + rcutor_hp = firsterr; } firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup); if (firsterr) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 733902c33dd2..7e2e03879c2e 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3792,8 +3792,6 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp) rnp = rdp->mynode; mask = rdp->grpmask; raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */ - rnp->qsmaskinitnext |= mask; - rnp->expmaskinitnext |= mask; if (!rdp->beenonline) WRITE_ONCE(rsp->ncpus, READ_ONCE(rsp->ncpus) + 1); rdp->beenonline = true; /* We have now been online. */ @@ -3860,6 +3858,32 @@ int rcutree_dead_cpu(unsigned int cpu) return 0; } +/* + * Mark the specified CPU as being online so that subsequent grace periods + * (both expedited and normal) will wait on it. Note that this means that + * incoming CPUs are not allowed to use RCU read-side critical sections + * until this function is called. Failing to observe this restriction + * will result in lockdep splats. + */ +void rcu_cpu_starting(unsigned int cpu) +{ + unsigned long flags; + unsigned long mask; + struct rcu_data *rdp; + struct rcu_node *rnp; + struct rcu_state *rsp; + + for_each_rcu_flavor(rsp) { + rdp = this_cpu_ptr(rsp->rda); + rnp = rdp->mynode; + mask = rdp->grpmask; + raw_spin_lock_irqsave_rcu_node(rnp, flags); + rnp->qsmaskinitnext |= mask; + rnp->expmaskinitnext |= mask; + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + } +} + #ifdef CONFIG_HOTPLUG_CPU /* * The CPU is exiting the idle loop into the arch_cpu_idle_dead() @@ -4209,8 +4233,10 @@ void __init rcu_init(void) * or the scheduler are operational. */ pm_notifier(rcu_pm_notify, 0); - for_each_online_cpu(cpu) + for_each_online_cpu(cpu) { rcutree_prepare_cpu(cpu); + rcu_cpu_starting(cpu); + } } #include "tree_exp.h" diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index f714f873bf9d..e99a5234d9ed 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -400,6 +400,7 @@ struct rcu_data { #ifdef CONFIG_RCU_FAST_NO_HZ struct rcu_head oom_head; #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ + atomic_long_t exp_workdone0; /* # done by workqueue. */ atomic_long_t exp_workdone1; /* # done by others #1. */ atomic_long_t exp_workdone2; /* # done by others #2. */ atomic_long_t exp_workdone3; /* # done by others #3. */ diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 6d86ab6ec2c9..24343eb87b58 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -359,7 +359,8 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp, struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu); if (raw_smp_processor_id() == cpu || - !(atomic_add_return(0, &rdtp->dynticks) & 0x1)) + !(atomic_add_return(0, &rdtp->dynticks) & 0x1) || + !(rnp->qsmaskinitnext & rdp->grpmask)) mask_ofl_test |= rdp->grpmask; } mask_ofl_ipi = rnp->expmask & ~mask_ofl_test; @@ -384,17 +385,16 @@ retry_ipi: mask_ofl_ipi &= ~mask; continue; } - /* Failed, raced with offline. */ + /* Failed, raced with CPU hotplug operation. */ raw_spin_lock_irqsave_rcu_node(rnp, flags); - if (cpu_online(cpu) && + if ((rnp->qsmaskinitnext & mask) && (rnp->expmask & mask)) { + /* Online, so delay for a bit and try again. */ raw_spin_unlock_irqrestore_rcu_node(rnp, flags); schedule_timeout_uninterruptible(1); - if (cpu_online(cpu) && - (rnp->expmask & mask)) - goto retry_ipi; - raw_spin_lock_irqsave_rcu_node(rnp, flags); + goto retry_ipi; } + /* CPU really is offline, so we can ignore it. */ if (!(rnp->expmask & mask)) mask_ofl_ipi &= ~mask; raw_spin_unlock_irqrestore_rcu_node(rnp, flags); @@ -427,12 +427,10 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp) jiffies_stall); if (ret > 0 || sync_rcu_preempt_exp_done(rnp_root)) return; - if (ret < 0) { - /* Hit a signal, disable CPU stall warnings. */ - swait_event(rsp->expedited_wq, - sync_rcu_preempt_exp_done(rnp_root)); - return; - } + WARN_ON(ret < 0); /* workqueues should not be signaled. */ + if (rcu_cpu_stall_suppress) + continue; + panic_on_rcu_stall(); pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {", rsp->name); ndetected = 0; @@ -500,7 +498,6 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s) * next GP, to proceed. */ mutex_lock(&rsp->exp_wake_mutex); - mutex_unlock(&rsp->exp_mutex); rcu_for_each_node_breadth_first(rsp, rnp) { if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s)) { @@ -516,6 +513,70 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s) mutex_unlock(&rsp->exp_wake_mutex); } +/* Let the workqueue handler know what it is supposed to do. */ +struct rcu_exp_work { + smp_call_func_t rew_func; + struct rcu_state *rew_rsp; + unsigned long rew_s; + struct work_struct rew_work; +}; + +/* + * Work-queue handler to drive an expedited grace period forward. + */ +static void wait_rcu_exp_gp(struct work_struct *wp) +{ + struct rcu_exp_work *rewp; + + /* Initialize the rcu_node tree in preparation for the wait. */ + rewp = container_of(wp, struct rcu_exp_work, rew_work); + sync_rcu_exp_select_cpus(rewp->rew_rsp, rewp->rew_func); + + /* Wait and clean up, including waking everyone. */ + rcu_exp_wait_wake(rewp->rew_rsp, rewp->rew_s); +} + +/* + * Given an rcu_state pointer and a smp_call_function() handler, kick + * off the specified flavor of expedited grace period. + */ +static void _synchronize_rcu_expedited(struct rcu_state *rsp, + smp_call_func_t func) +{ + struct rcu_data *rdp; + struct rcu_exp_work rew; + struct rcu_node *rnp; + unsigned long s; + + /* If expedited grace periods are prohibited, fall back to normal. */ + if (rcu_gp_is_normal()) { + wait_rcu_gp(rsp->call); + return; + } + + /* Take a snapshot of the sequence number. */ + s = rcu_exp_gp_seq_snap(rsp); + if (exp_funnel_lock(rsp, s)) + return; /* Someone else did our work for us. */ + + /* Marshall arguments and schedule the expedited grace period. */ + rew.rew_func = func; + rew.rew_rsp = rsp; + rew.rew_s = s; + INIT_WORK_ONSTACK(&rew.rew_work, wait_rcu_exp_gp); + schedule_work(&rew.rew_work); + + /* Wait for expedited grace period to complete. */ + rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id()); + rnp = rcu_get_root(rsp); + wait_event(rnp->exp_wq[(s >> 1) & 0x3], + sync_exp_work_done(rsp, + &rdp->exp_workdone0, s)); + + /* Let the next expedited grace period start. */ + mutex_unlock(&rsp->exp_mutex); +} + /** * synchronize_sched_expedited - Brute-force RCU-sched grace period * @@ -534,29 +595,13 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s) */ void synchronize_sched_expedited(void) { - unsigned long s; struct rcu_state *rsp = &rcu_sched_state; /* If only one CPU, this is automatically a grace period. */ if (rcu_blocking_is_gp()) return; - /* If expedited grace periods are prohibited, fall back to normal. */ - if (rcu_gp_is_normal()) { - wait_rcu_gp(call_rcu_sched); - return; - } - - /* Take a snapshot of the sequence number. */ - s = rcu_exp_gp_seq_snap(rsp); - if (exp_funnel_lock(rsp, s)) - return; /* Someone else did our work for us. */ - - /* Initialize the rcu_node tree in preparation for the wait. */ - sync_rcu_exp_select_cpus(rsp, sync_sched_exp_handler); - - /* Wait and clean up, including waking everyone. */ - rcu_exp_wait_wake(rsp, s); + _synchronize_rcu_expedited(rsp, sync_sched_exp_handler); } EXPORT_SYMBOL_GPL(synchronize_sched_expedited); @@ -620,23 +665,8 @@ static void sync_rcu_exp_handler(void *info) void synchronize_rcu_expedited(void) { struct rcu_state *rsp = rcu_state_p; - unsigned long s; - - /* If expedited grace periods are prohibited, fall back to normal. */ - if (rcu_gp_is_normal()) { - wait_rcu_gp(call_rcu); - return; - } - - s = rcu_exp_gp_seq_snap(rsp); - if (exp_funnel_lock(rsp, s)) - return; /* Someone else did our work for us. */ - - /* Initialize the rcu_node tree in preparation for the wait. */ - sync_rcu_exp_select_cpus(rsp, sync_rcu_exp_handler); - /* Wait for ->blkd_tasks lists to drain, then wake everyone up. */ - rcu_exp_wait_wake(rsp, s); + _synchronize_rcu_expedited(rsp, sync_rcu_exp_handler); } EXPORT_SYMBOL_GPL(synchronize_rcu_expedited); diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c index 86782f9a4604..b1f28972872c 100644 --- a/kernel/rcu/tree_trace.c +++ b/kernel/rcu/tree_trace.c @@ -185,16 +185,17 @@ static int show_rcuexp(struct seq_file *m, void *v) int cpu; struct rcu_state *rsp = (struct rcu_state *)m->private; struct rcu_data *rdp; - unsigned long s1 = 0, s2 = 0, s3 = 0; + unsigned long s0 = 0, s1 = 0, s2 = 0, s3 = 0; for_each_possible_cpu(cpu) { rdp = per_cpu_ptr(rsp->rda, cpu); + s0 += atomic_long_read(&rdp->exp_workdone0); s1 += atomic_long_read(&rdp->exp_workdone1); s2 += atomic_long_read(&rdp->exp_workdone2); s3 += atomic_long_read(&rdp->exp_workdone3); } - seq_printf(m, "s=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n", - rsp->expedited_sequence, s1, s2, s3, + seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n", + rsp->expedited_sequence, s0, s1, s2, s3, atomic_long_read(&rsp->expedited_normal), atomic_read(&rsp->expedited_need_qs), rsp->expedited_sequence / 2); |