diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcutiny.c | 2 | ||||
| -rw-r--r-- | kernel/rcutorture.c | 54 | ||||
| -rw-r--r-- | kernel/rcutree.c | 208 | ||||
| -rw-r--r-- | kernel/rcutree.h | 19 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 11 | ||||
| -rw-r--r-- | kernel/rcutree_trace.c | 318 | ||||
| -rw-r--r-- | kernel/sched/core.c | 6 | ||||
| -rw-r--r-- | kernel/srcu.c | 8 |
8 files changed, 367 insertions, 259 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index e4c6a598d6f..e7dce58f9c2 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -195,7 +195,7 @@ EXPORT_SYMBOL(rcu_is_cpu_idle); */ int rcu_is_cpu_rrupt_from_idle(void) { - return rcu_dynticks_nesting <= 0; + return rcu_dynticks_nesting <= 1; } /* diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index aaa7b9f3532..31dea01c85f 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -339,7 +339,6 @@ rcu_stutter_wait(char *title) struct rcu_torture_ops { void (*init)(void); - void (*cleanup)(void); int (*readlock)(void); void (*read_delay)(struct rcu_random_state *rrsp); void (*readunlock)(int idx); @@ -431,7 +430,6 @@ static void rcu_torture_deferred_free(struct rcu_torture *p) static struct rcu_torture_ops rcu_ops = { .init = NULL, - .cleanup = NULL, .readlock = rcu_torture_read_lock, .read_delay = rcu_read_delay, .readunlock = rcu_torture_read_unlock, @@ -475,7 +473,6 @@ static void rcu_sync_torture_init(void) static struct rcu_torture_ops rcu_sync_ops = { .init = rcu_sync_torture_init, - .cleanup = NULL, .readlock = rcu_torture_read_lock, .read_delay = rcu_read_delay, .readunlock = rcu_torture_read_unlock, @@ -493,7 +490,6 @@ static struct rcu_torture_ops rcu_sync_ops = { static struct rcu_torture_ops rcu_expedited_ops = { .init = rcu_sync_torture_init, - .cleanup = NULL, .readlock = rcu_torture_read_lock, .read_delay = rcu_read_delay, /* just reuse rcu's version. */ .readunlock = rcu_torture_read_unlock, @@ -536,7 +532,6 @@ static void rcu_bh_torture_deferred_free(struct rcu_torture *p) static struct rcu_torture_ops rcu_bh_ops = { .init = NULL, - .cleanup = NULL, .readlock = rcu_bh_torture_read_lock, .read_delay = rcu_read_delay, /* just reuse rcu's version. */ .readunlock = rcu_bh_torture_read_unlock, @@ -553,7 +548,6 @@ static struct rcu_torture_ops rcu_bh_ops = { static struct rcu_torture_ops rcu_bh_sync_ops = { .init = rcu_sync_torture_init, - .cleanup = NULL, .readlock = rcu_bh_torture_read_lock, .read_delay = rcu_read_delay, /* just reuse rcu's version. */ .readunlock = rcu_bh_torture_read_unlock, @@ -570,7 +564,6 @@ static struct rcu_torture_ops rcu_bh_sync_ops = { static struct rcu_torture_ops rcu_bh_expedited_ops = { .init = rcu_sync_torture_init, - .cleanup = NULL, .readlock = rcu_bh_torture_read_lock, .read_delay = rcu_read_delay, /* just reuse rcu's version. */ .readunlock = rcu_bh_torture_read_unlock, @@ -589,19 +582,7 @@ static struct rcu_torture_ops rcu_bh_expedited_ops = { * Definitions for srcu torture testing. */ -static struct srcu_struct srcu_ctl; - -static void srcu_torture_init(void) -{ - init_srcu_struct(&srcu_ctl); - rcu_sync_torture_init(); -} - -static void srcu_torture_cleanup(void) -{ - synchronize_srcu(&srcu_ctl); - cleanup_srcu_struct(&srcu_ctl); -} +DEFINE_STATIC_SRCU(srcu_ctl); static int srcu_torture_read_lock(void) __acquires(&srcu_ctl) { @@ -672,8 +653,7 @@ static int srcu_torture_stats(char *page) } static struct rcu_torture_ops srcu_ops = { - .init = srcu_torture_init, - .cleanup = srcu_torture_cleanup, + .init = rcu_sync_torture_init, .readlock = srcu_torture_read_lock, .read_delay = srcu_read_delay, .readunlock = srcu_torture_read_unlock, @@ -687,8 +667,7 @@ static struct rcu_torture_ops srcu_ops = { }; static struct rcu_torture_ops srcu_sync_ops = { - .init = srcu_torture_init, - .cleanup = srcu_torture_cleanup, + .init = rcu_sync_torture_init, .readlock = srcu_torture_read_lock, .read_delay = srcu_read_delay, .readunlock = srcu_torture_read_unlock, @@ -712,8 +691,7 @@ static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl) } static struct rcu_torture_ops srcu_raw_ops = { - .init = srcu_torture_init, - .cleanup = srcu_torture_cleanup, + .init = rcu_sync_torture_init, .readlock = srcu_torture_read_lock_raw, .read_delay = srcu_read_delay, .readunlock = srcu_torture_read_unlock_raw, @@ -727,8 +705,7 @@ static struct rcu_torture_ops srcu_raw_ops = { }; static struct rcu_torture_ops srcu_raw_sync_ops = { - .init = srcu_torture_init, - .cleanup = srcu_torture_cleanup, + .init = rcu_sync_torture_init, .readlock = srcu_torture_read_lock_raw, .read_delay = srcu_read_delay, .readunlock = srcu_torture_read_unlock_raw, @@ -747,8 +724,7 @@ static void srcu_torture_synchronize_expedited(void) } static struct rcu_torture_ops srcu_expedited_ops = { - .init = srcu_torture_init, - .cleanup = srcu_torture_cleanup, + .init = rcu_sync_torture_init, .readlock = srcu_torture_read_lock, .read_delay = srcu_read_delay, .readunlock = srcu_torture_read_unlock, @@ -783,7 +759,6 @@ static void rcu_sched_torture_deferred_free(struct rcu_torture *p) static struct rcu_torture_ops sched_ops = { .init = rcu_sync_torture_init, - .cleanup = NULL, .readlock = sched_torture_read_lock, .read_delay = rcu_read_delay, /* just reuse rcu's version. */ .readunlock = sched_torture_read_unlock, @@ -799,7 +774,6 @@ static struct rcu_torture_ops sched_ops = { static struct rcu_torture_ops sched_sync_ops = { .init = rcu_sync_torture_init, - .cleanup = NULL, .readlock = sched_torture_read_lock, .read_delay = rcu_read_delay, /* just reuse rcu's version. */ .readunlock = sched_torture_read_unlock, @@ -814,7 +788,6 @@ static struct rcu_torture_ops sched_sync_ops = { static struct rcu_torture_ops sched_expedited_ops = { .init = rcu_sync_torture_init, - .cleanup = NULL, .readlock = sched_torture_read_lock, .read_delay = rcu_read_delay, /* just reuse rcu's version. */ .readunlock = sched_torture_read_unlock, @@ -1396,12 +1369,16 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag) "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d " "test_boost=%d/%d test_boost_interval=%d " "test_boost_duration=%d shutdown_secs=%d " + "stall_cpu=%d stall_cpu_holdoff=%d " + "n_barrier_cbs=%d " "onoff_interval=%d onoff_holdoff=%d\n", torture_type, tag, nrealreaders, nfakewriters, stat_interval, verbose, test_no_idle_hz, shuffle_interval, stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter, test_boost, cur_ops->can_boost, test_boost_interval, test_boost_duration, shutdown_secs, + stall_cpu, stall_cpu_holdoff, + n_barrier_cbs, onoff_interval, onoff_holdoff); } @@ -1502,6 +1479,7 @@ rcu_torture_onoff(void *arg) unsigned long delta; int maxcpu = -1; DEFINE_RCU_RANDOM(rand); + int ret; unsigned long starttime; VERBOSE_PRINTK_STRING("rcu_torture_onoff task started"); @@ -1522,7 +1500,13 @@ rcu_torture_onoff(void *arg) torture_type, cpu); starttime = jiffies; n_offline_attempts++; - if (cpu_down(cpu) == 0) { + ret = cpu_down(cpu); + if (ret) { + if (verbose) + pr_alert("%s" TORTURE_FLAG + "rcu_torture_onoff task: offline %d failed: errno %d\n", + torture_type, cpu, ret); + } else { if (verbose) pr_alert("%s" TORTURE_FLAG "rcu_torture_onoff task: offlined %d\n", @@ -1936,8 +1920,6 @@ rcu_torture_cleanup(void) rcu_torture_stats_print(); /* -After- the stats thread is stopped! */ - if (cur_ops->cleanup) - cur_ops->cleanup(); if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error) rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE"); else if (n_online_successes != n_online_attempts || diff --git a/kernel/rcutree.c b/kernel/rcutree.c index effd47a54b3..5ffadcc3bb2 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -68,9 +68,9 @@ static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS]; .level = { &sname##_state.node[0] }, \ .call = cr, \ .fqs_state = RCU_GP_IDLE, \ - .gpnum = -300, \ - .completed = -300, \ - .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.onofflock), \ + .gpnum = 0UL - 300UL, \ + .completed = 0UL - 300UL, \ + .orphan_lock = __RAW_SPIN_LOCK_UNLOCKED(&sname##_state.orphan_lock), \ .orphan_nxttail = &sname##_state.orphan_nxtlist, \ .orphan_donetail = &sname##_state.orphan_donelist, \ .barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \ @@ -212,13 +212,13 @@ DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { #endif }; -static int blimit = 10; /* Maximum callbacks per rcu_do_batch. */ -static int qhimark = 10000; /* If this many pending, ignore blimit. */ -static int qlowmark = 100; /* Once only this many pending, use blimit. */ +static long blimit = 10; /* Maximum callbacks per rcu_do_batch. */ +static long qhimark = 10000; /* If this many pending, ignore blimit. */ +static long qlowmark = 100; /* Once only this many pending, use blimit. */ -module_param(blimit, int, 0444); -module_param(qhimark, int, 0444); -module_param(qlowmark, int, 0444); +module_param(blimit, long, 0444); +module_param(qhimark, long, 0444); +module_param(qlowmark, long, 0444); int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */ int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; @@ -873,6 +873,29 @@ static void record_gp_stall_check_time(struct rcu_state *rsp) rsp->jiffies_stall = jiffies + jiffies_till_stall_check(); } +/* + * Dump stacks of all tasks running on stalled CPUs. This is a fallback + * for architectures that do not implement trigger_all_cpu_backtrace(). + * The NMI-triggered stack traces are more accurate because they are + * printed by the target CPU. + */ +static void rcu_dump_cpu_stacks(struct rcu_state *rsp) +{ + int cpu; + unsigned long flags; + struct rcu_node *rnp; + + rcu_for_each_leaf_node(rsp, rnp) { + raw_spin_lock_irqsave(&rnp->lock, flags); + if (rnp->qsmask != 0) { + for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) + if (rnp->qsmask & (1UL << cpu)) + dump_cpu_task(rnp->grplo + cpu); + } + raw_spin_unlock_irqrestore(&rnp->lock, flags); + } +} + static void print_other_cpu_stall(struct rcu_state *rsp) { int cpu; @@ -880,6 +903,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp) unsigned long flags; int ndetected = 0; struct rcu_node *rnp = rcu_get_root(rsp); + long totqlen = 0; /* Only let one CPU complain about others per time interval. */ @@ -924,12 +948,15 @@ static void print_other_cpu_stall(struct rcu_state *rsp) raw_spin_unlock_irqrestore(&rnp->lock, flags); print_cpu_stall_info_end(); - printk(KERN_CONT "(detected by %d, t=%ld jiffies)\n", - smp_processor_id(), (long)(jiffies - rsp->gp_start)); + for_each_possible_cpu(cpu) + totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen; + pr_cont("(detected by %d, t=%ld jiffies, g=%lu, c=%lu, q=%lu)\n", + smp_processor_id(), (long)(jiffies - rsp->gp_start), + rsp->gpnum, rsp->completed, totqlen); if (ndetected == 0) printk(KERN_ERR "INFO: Stall ended before state dump start\n"); else if (!trigger_all_cpu_backtrace()) - dump_stack(); + rcu_dump_cpu_stacks(rsp); /* Complain about tasks blocking the grace period. */ @@ -940,8 +967,10 @@ static void print_other_cpu_stall(struct rcu_state *rsp) static void print_cpu_stall(struct rcu_state *rsp) { + int cpu; unsigned long flags; struct rcu_node *rnp = rcu_get_root(rsp); + long totqlen = 0; /* * OK, time to rat on ourselves... @@ -952,7 +981,10 @@ static void print_cpu_stall(struct rcu_state *rsp) print_cpu_stall_info_begin(); print_cpu_stall_info(rsp, smp_processor_id()); print_cpu_stall_info_end(); - printk(KERN_CONT " (t=%lu jiffies)\n", jiffies - rsp->gp_start); + for_each_possible_cpu(cpu) + totqlen += per_cpu_ptr(rsp->rda, cpu)->qlen; + pr_cont(" (t=%lu jiffies g=%lu c=%lu q=%lu)\n", + jiffies - rsp->gp_start, rsp->gpnum, rsp->completed, totqlen); if (!trigger_all_cpu_backtrace()) dump_stack(); @@ -1404,15 +1436,37 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) !cpu_needs_another_gp(rsp, rdp)) { /* * Either we have not yet spawned the grace-period - * task or this CPU does not need another grace period. + * task, this CPU does not need another grace period, + * or a grace period is already in progress. * Either way, don't start a new grace period. */ raw_spin_unlock_irqrestore(&rnp->lock, flags); return; } + /* + * Because there is no grace period in progress right now, + * any callbacks we have up to this point will be satisfied + * by the next grace period. So promote all callbacks to be + * handled after the end of the next grace period. If the + * CPU is not yet aware of the end of the previous grace period, + * we need to allow for the callback advancement that will + * occur when it does become aware. Deadlock prevents us from + * making it aware at this point: We cannot acquire a leaf + * rcu_node ->lock while holding the root rcu_node ->lock. + */ + rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; + if (rdp->completed == rsp->completed) + rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL]; + rsp->gp_flags = RCU_GP_FLAG_INIT; - raw_spin_unlock_irqrestore(&rnp->lock, flags); + raw_spin_unlock(&rnp->lock); /* Interrupts remain disabled. */ + + /* Ensure that CPU is aware of completion of last grace period. */ + rcu_process_gp_end(rsp, rdp); + local_irq_restore(flags); + + /* Wake up rcu_gp_kthread() to start the grace period. */ wake_up(&rsp->gp_wq); } @@ -1573,7 +1627,7 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp) /* * Send the specified CPU's RCU callbacks to the orphanage. The * specified CPU must be offline, and the caller must hold the - * ->onofflock. + * ->orphan_lock. */ static void rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp, @@ -1581,8 +1635,8 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp, { /* * Orphan the callbacks. First adjust the counts. This is safe - * because ->onofflock excludes _rcu_barrier()'s adoption of - * the callbacks, thus no memory barrier is required. + * because _rcu_barrier() excludes CPU-hotplug operations, so it + * cannot be running now. Thus no memory barrier is required. */ if (rdp->nxtlist != NULL) { rsp->qlen_lazy += rdp->qlen_lazy; @@ -1623,7 +1677,7 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp, /* * Adopt the RCU callbacks from the specified rcu_state structure's - * orphanage. The caller must hold the ->onofflock. + * orphanage. The caller must hold the ->orphan_lock. */ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp) { @@ -1702,7 +1756,7 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) /* Exclude any attempts to start a new grace period. */ mutex_lock(&rsp->onoff_mutex); - raw_spin_lock_irqsave(&rsp->onofflock, flags); + raw_spin_lock_irqsave(&rsp->orphan_lock, flags); /* Orphan the dead CPU's callbacks, and adopt them if appropriate. */ rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp); @@ -1729,10 +1783,10 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) /* * We still hold the leaf rcu_node structure lock here, and * irqs are still disabled. The reason for this subterfuge is - * because invoking rcu_report_unblock_qs_rnp() with ->onofflock + * because invoking rcu_report_unblock_qs_rnp() with ->orphan_lock * held leads to deadlock. */ - raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */ + raw_spin_unlock(&rsp->orphan_lock); /* irqs remain disabled. */ rnp = rdp->mynode; if (need_report & RCU_OFL_TASKS_NORM_GP) rcu_report_unblock_qs_rnp(rnp, flags); @@ -1769,7 +1823,8 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) { unsigned long flags; struct rcu_head *next, *list, **tail; - int bl, count, count_lazy, i; + long bl, count, count_lazy; + int i; /* If no callbacks are ready, just return.*/ if (!cpu_has_callbacks_ready_to_invoke(rdp)) { @@ -2205,10 +2260,28 @@ static inline int rcu_blocking_is_gp(void) * rcu_read_lock_sched(). * * This means that all preempt_disable code sequences, including NMI and - * hardware-interrupt handlers, in progress on entry will have completed - * before this primitive returns. However, this does not guarantee that - * softirq handlers will have completed, since in some kernels, these - * handlers can run in process context, and can block. + * non-threaded hardware-interrupt handlers, in progress on entry will + * have completed before this primitive returns. However, this does not + * guarantee that softirq handlers will have completed, since in some + * kernels, these handlers can run in process context, and can block. + * + * Note that this guarantee implies further memory-ordering guarantees. + * On systems with more than one CPU, when synchronize_sched() returns, + * each CPU is guaranteed to have executed a full memory barrier since the + * end of its last RCU-sched read-side critical section whose beginning + * preceded the call to synchronize_sched(). In addition, each CPU having + * an RCU read-side critical section that extends beyond the return from + * synchronize_sched() is guaranteed to have executed a full memory barrier + * after the beginning of synchronize_sched() and before the beginning of + * that RCU read-side critical section. Note that these guarantees include + * CPUs that are offline, idle, or executing in user mode, as well as CPUs + * that are executing in the kernel. + * + * Furthermore, if CPU A invoked synchronize_sched(), which returned + * to its caller on CPU B, then both CPU A and CPU B are guaranteed + * to have executed a full memory barrier during the execution of + * synchronize_sched() -- even if CPU A and CPU B are the same CPU (but + * again only if the system has more than one CPU). * * This primitive provides the guarantees made by the (now removed) * synchronize_kernel() API. In contrast, synchronize_rcu() only @@ -2239,6 +2312,9 @@ EXPORT_SYMBOL_GPL(synchronize_sched); * read-side critical sections have completed. RCU read-side critical * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(), * and may be nested. + * + * See the description of synchronize_sched() for more detailed information + * on memory ordering guarantees. */ void synchronize_rcu_bh(void) { @@ -2255,9 +2331,6 @@ void synchronize_rcu_bh(void) } EXPORT_SYMBOL_GPL(synchronize_rcu_bh); -static atomic_t sync_sched_expedited_started = ATOMIC_INIT(0); -static atomic_t sync_sched_expedited_done = ATOMIC_INIT(0); - static int synchronize_sched_expedited_cpu_stop(void *data) { /* @@ -2314,10 +2387,32 @@ static int synchronize_sched_expedited_cpu_stop(void *data) */ void synchronize_sched_expedited(void) { - int firstsnap, s, snap, trycount = 0; + long firstsnap, s, snap; + int trycount = 0; + struct rcu_state *rsp = &rcu_sched_state; - /* Note that atomic_inc_return() implies full memory barrier. */ - firstsnap = snap = atomic_inc_return(&sync_sched_expedited_started); + /* + * If we are in danger of counter wrap, just do synchronize_sched(). + * By allowing sync_sched_expedited_started to advance no more than + * ULONG_MAX/8 ahead of sync_sched_expedited_done, we are ensuring + * that more than 3.5 billion CPUs would be required to force a + * counter wrap on a 32-bit system. Quite a few more CPUs would of + * course be required on a 64-bit system. + */ + if (ULONG_CMP_GE((ulong)atomic_long_read(&rsp->expedited_start), + (ulong)atomic_long_read(&rsp->expedited_done) + + ULONG_MAX / 8)) { + synchronize_sched(); + atomic_long_inc(&rsp->expedited_wrap); + return; + } + + /* + * Take a ticket. Note that atomic_inc_return() implies a + * full memory barrier. + */ + snap = atomic_long_inc_return(&rsp->expedited_start); + firstsnap = snap; get_online_cpus(); WARN_ON_ONCE(cpu_is_offline(raw_smp_processor_id())); @@ -2329,48 +2424,65 @@ void synchronize_sched_expedited(void) synchronize_sched_expedited_cpu_stop, NULL) == -EAGAIN) { put_online_cpus(); + atomic_long_inc(&rsp->expedited_tryfail); + + /* Check to see if someone else did our work for us. */ + s = atomic_long_read(&rsp->expedited_done); + if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) { + /* ensure test happens before caller kfree */ + smp_mb__before_atomic_inc(); /* ^^^ */ + atomic_long_inc(&rsp->expedited_workdone1); + return; + } /* No joy, try again later. Or just synchronize_sched(). */ if (trycount++ < 10) { udelay(trycount * num_online_cpus()); } else { wait_rcu_gp(call_rcu_sched); + atomic_long_inc(&rsp->expedited_normal); return; } - /* Check to see if someone else did our work for us. */ - s = atomic_read(&sync_sched_expedited_done); - if (UINT_CMP_GE((unsigned)s, (unsigned)firstsnap)) { - smp_mb(); /* ensure test happens before caller kfree */ + /* Recheck to see if someone else did our work for us. */ + s = atomic_long_read(&rsp->expedited_done); + if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) { + /* ensure test happens before caller kfree */ + smp_mb__before_atomic_inc(); /* ^^^ */ + atomic_long_inc(&rsp->expedited_workdone2); return; } /* * Refetching sync_sched_expedited_started allows later - * callers to piggyback on our grace period. We subtract - * 1 to get the same token that the last incrementer got. - * We retry after they started, so our grace period works - * for them, and they started after our first try, so their - * grace period works for us. + * callers to piggyback on our grace period. We retry + * after they started, so our grace period works for them, + * and they started after our first try, so their grace + * period works for us. */ get_online_cpus(); - snap = atomic_read(&sync_sched_expedited_started); + snap = atomic_long_read(&rsp->expedited_start); smp_mb(); /* ensure read is before try_stop_cpus(). */ } + atomic_long_inc(&rsp->expedited_stoppedcpus); /* * Everyone up to our most recent fetch is covered by our grace * period. Update the counter, but only if our work is still * relevant -- which it won't be if someone who started later - * than we did beat us to the punch. + * than we did already did their update. */ do { - s = atomic_read(&sync_sched_expedited_done); - if (UINT_CMP_GE((unsigned)s, (unsigned)snap)) { - smp_mb(); /* ensure test happens before caller kfree */ + atomic_long_inc(&rsp->expedited_done_tries); + s = atomic_long_read(&rsp->expedited_done); + if (ULONG_CMP_GE((ulong)s, (ulong)snap)) { + /* ensure test happens before caller kfree */ + smp_mb__before_atomic_inc(); /* ^^^ */ + atomic_long_inc(&rsp->expedited_done_lost); break; } - } while (atomic_cmpxchg(&sync_sched_expedited_done, s, snap) != s); + } while (atomic_long_cmpxchg(&rsp->expedited_done, s, snap) != s); + atomic_long_inc(&rsp->expedited_done_exit); put_online_cpus(); } diff --git a/kernel/rcutree.h b/kernel/rcutree.h index a240f032848..d274af35721 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -383,9 +383,8 @@ struct rcu_state { /* End of fields guarded by root rcu_node's lock. */ - raw_spinlock_t onofflock ____cacheline_internodealigned_in_smp; - /* exclude on/offline and */ - /* starting new GP. */ + raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp; + /* Protect following fields. */ struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */ /* need a grace period. */ struct rcu_head **orphan_nxttail; /* Tail of above. */ @@ -394,7 +393,7 @@ struct rcu_state { struct rcu_head **orphan_donetail; /* Tail of above. */ long qlen_lazy; /* Number of lazy callbacks. */ long qlen; /* Total number of callbacks. */ - /* End of fields guarded by onofflock. */ + /* End of fields guarded by orphan_lock. */ struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */ @@ -405,6 +404,18 @@ struct rcu_state { /* _rcu_barrier(). */ /* End of fields guarded by barrier_mutex. */ + atomic_long_t expedited_start; /* Starting ticket. */ + atomic_long_t expedited_done; /* Done ticket. */ + atomic_long_t expedited_wrap; /* # near-wrap incidents. */ + atomic_long_t expedited_tryfail; /* # acquisition failures. */ + atomic_long_t expedited_workdone1; /* # done by others #1. */ + atomic_long_t expedited_workdone2; /* # done by others #2. */ + atomic_long_t expedited_normal; /* # fallbacks to normal. */ + atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */ + atomic_long_t expedited_done_tries; /* # tries to update _done. */ + atomic_long_t expedited_done_lost; /* # times beaten to _done. */ + atomic_long_t expedited_done_exit; /* # times exited _done loop. */ + unsigned long jiffies_force_qs; /* Time at which to invoke */ /* force_quiescent_state(). */ unsigned long n_force_qs; /* Number of calls to */ diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index c177ba0cce9..5ce3352505e 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -670,6 +670,9 @@ EXPORT_SYMBOL_GPL(kfree_call_rcu); * concurrently with new RCU read-side critical sections that began while * synchronize_rcu() was waiting. RCU read-side critical sections are * delimited by rcu_read_lock() and rcu_read_unlock(), and may be nested. + * + * See the description of synchronize_sched() for more detailed information + * on memory ordering guarantees. */ void synchronize_rcu(void) { @@ -760,7 +763,8 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp, * grace period for the specified rcu_node structure. If there are no such * tasks, report it up the rcu_node hierarchy. * - * Caller must hold sync_rcu_preempt_exp_mutex and rsp->onofflock. + * Caller must hold sync_rcu_preempt_exp_mutex and must exclude + * CPU hotplug operations. */ static void sync_rcu_preempt_exp_init(struct rcu_state *rsp, struct rcu_node *rnp) @@ -878,6 +882,11 @@ EXPORT_SYMBOL_GPL(synchronize_rcu_expedited); /** * rcu_barrier - Wait until all in-flight call_rcu() callbacks complete. + * + * Note that this primitive does not necessarily wait for an RCU grace period + * to complete. For example, if there are no RCU callbacks queued anywhere + * in the system, then rcu_barrier() is within its rights to return + * immediately, without waiting for anything, much less an RCU grace period. */ void rcu_barrier(void) { diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 693513bc50e..f9512687a6e 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -46,29 +46,58 @@ #define RCU_TREE_NONCORE #include "rcutree.h" -static int show_rcubarrier(struct seq_file *m, void *unused) +#define ulong2long(a) (*(long *)(&(a))) + +static int r_open(struct inode *inode, struct file *file, + const struct seq_operations *op) { - struct rcu_state *rsp; + int ret = seq_open(file, op); + if (!ret) { + struct seq_file *m = (struct seq_file *)file->private_data; + m->private = inode->i_private; + } + return ret; +} + +static void *r_start(struct seq_file *m, loff_t *pos) +{ + struct rcu_state *rsp = (struct rcu_state *)m->private; + *pos = cpumask_next(*pos - 1, cpu_possible_mask); + if ((*pos) < nr_cpu_ids) + return per_cpu_ptr(rsp->rda, *pos); + return NULL; +} - for_each_rcu_flavor(rsp) - seq_printf(m, "%s: bcc: %d nbd: %lu\n", - rsp->name, - atomic_read(&rsp->barrier_cpu_count), - rsp->n_barrier_done); +static void *r_next(struct seq_file *m, void *v, loff_t *pos) +{ + (*pos)++; + return r_start(m, pos); +} + +static void r_stop(struct seq_file *m, void *v) +{ +} + +static int show_rcubarrier(struct seq_file *m, void *v) +{ + struct rcu_state *rsp = (struct rcu_state *)m->private; + seq_printf(m, "bcc: %d nbd: %lu\n", + atomic_read(&rsp->barrier_cpu_count), + rsp->n_barrier_done); return 0; } static int rcubarrier_open(struct inode *inode, struct file *file) { - return single_open(file, show_rcubarrier, NULL); + return single_open(file, show_rcubarrier, inode->i_private); } static const struct file_operations rcubarrier_fops = { .owner = THIS_MODULE, .open = rcubarrier_open, .read = seq_read, - .llseek = seq_lseek, - .release = single_release, + .llseek = no_llseek, + .release = seq_release, }; #ifdef CONFIG_RCU_BOOST @@ -86,10 +115,10 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) { if (!rdp->beenonline) return; - seq_printf(m, "%3d%cc=%lu g=%lu pq=%d qp=%d", + seq_printf(m, "%3d%cc=%ld g=%ld pq=%d qp=%d", rdp->cpu, cpu_is_offline(rdp->cpu) ? '!' : ' ', - rdp->completed, rdp->gpnum, + ulong2long(rdp->completed), ulong2long(rdp->gpnum), rdp->passed_quiesce, rdp->qs_pending); seq_printf(m, " dt=%d/%llx/%d df=%lu", atomic_read(&rdp->dynticks->dynticks), @@ -118,97 +147,62 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); } -static int show_rcudata(struct seq_file *m, void *unused) +static int show_rcudata(struct seq_file *m, void *v) { - int cpu; - struct rcu_state *rsp; - - for_each_rcu_flavor(rsp) { - seq_printf(m, "%s:\n", rsp->name); - for_each_possible_cpu(cpu) - print_one_rcu_data(m, per_cpu_ptr(rsp->rda, cpu)); - } + print_one_rcu_data(m, (struct rcu_data *)v); return 0; } +static const struct seq_operations rcudate_op = { + .start = r_start, + .next = r_next, + .stop = r_stop, + .show = show_rcudata, +}; + static int rcudata_open(struct inode *inode, struct file *file) { - return single_open(file, show_rcudata, NULL); + return r_open(inode, file, &rcudate_op); } static const struct file_operations rcudata_fops = { .owner = THIS_MODULE, .open = rcudata_open, .read = seq_read, - .llseek = seq_lseek, - .release = single_release, + .llseek = no_llseek, + .release = seq_release, }; -static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp) -{ - if (!rdp->beenonline) - return; - seq_printf(m, "%d,%s,%lu,%lu,%d,%d", - rdp->cpu, - cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"", - rdp->completed, rdp->gpnum, - rdp->passed_quiesce, rdp->qs_pending); - seq_printf(m, ",%d,%llx,%d,%lu", - atomic_read(&rdp->dynticks->dynticks), - rdp->dynticks->dynticks_nesting, - rdp->dynticks->dynticks_nmi_nesting, - rdp->dynticks_fqs); - seq_printf(m, ",%lu", rdp->offline_fqs); - seq_printf(m, ",%ld,%ld,\"%c%c%c%c\"", rdp->qlen_lazy, rdp->qlen, - ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != - rdp->nxttail[RCU_NEXT_TAIL]], - ".R"[rdp->nxttail[RCU_WAIT_TAIL] != - rdp->nxttail[RCU_NEXT_READY_TAIL]], - ".W"[rdp->nxttail[RCU_DONE_TAIL] != - rdp->nxttail[RCU_WAIT_TAIL]], - ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]); -#ifdef CONFIG_RCU_BOOST - seq_printf(m, ",%d,\"%c\"", - per_cpu(rcu_cpu_has_work, rdp->cpu), - convert_kthread_status(per_cpu(rcu_cpu_kthread_status, - rdp->cpu))); -#endif /* #ifdef CONFIG_RCU_BOOST */ - seq_printf(m, ",%ld", rdp->blimit); - seq_printf(m, ",%lu,%lu,%lu\n", - rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); -} - -static int show_rcudata_csv(struct seq_file *m, void *unused) +static int show_rcuexp(struct seq_file *m, void *v) { - int cpu; - struct rcu_state *rsp; - - seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pq\","); - seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\","); - seq_puts(m, "\"of\",\"qll\",\"ql\",\"qs\""); -#ifdef CONFIG_RCU_BOOST - seq_puts(m, "\"kt\",\"ktl\""); -#endif /* #ifdef CONFIG_RCU_BOOST */ - seq_puts(m, ",\"b\",\"ci\",\"co\",\"ca\"\n"); - for_each_rcu_flavor(rsp) { - seq_printf(m, "\"%s:\"\n", rsp->name); - for_each_possible_cpu(cpu) - print_one_rcu_data_csv(m, per_cpu_ptr(rsp->rda, cpu)); - } + struct rcu_state *rsp = (struct rcu_state *)m->private; + + seq_printf(m, "s=%lu d=%lu w=%lu tf=%lu wd1=%lu wd2=%lu n=%lu sc=%lu dt=%lu dl=%lu dx=%lu\n", + atomic_long_read(&rsp->expedited_start), + atomic_long_read(&rsp->expedited_done), + atomic_long_read(&rsp->expedited_wrap), + atomic_long_read(&rsp->expedited_tryfail), + atomic_long_read(&rsp->expedited_workdone1), + atomic_long_read(&rsp->expedited_workdone2), + atomic_long_read(&rsp->expedited_normal), + atomic_long_read(&rsp->expedited_stoppedcpus), + atomic_long_read(&rsp->expedited_done_tries), + atomic_long_read(&rsp->expedited_done_lost), + atomic_long_read(&rsp->expedited_done_exit)); return 0; } -static int rcudata_csv_open(struct inode *inode, struct file *file) +static int rcuexp_open(struct inode *inode, struct file *file) { - return single_open(file, show_rcudata_csv, NULL); + return single_open(file, show_rcuexp, inode->i_private); } -static const struct file_operations rcudata_csv_fops = { +static const struct file_operations rcuexp_fops = { .owner = THIS_MODULE, - .open = rcudata_csv_open, + .open = rcuexp_open, .read = seq_read, - .llseek = seq_lseek, - .release = single_release, + .llseek = no_llseek, + .release = seq_release, }; #ifdef CONFIG_RCU_BOOST @@ -254,27 +248,11 @@ static const struct file_operations rcu_node_boost_fops = { .owner = THIS_MODULE, .open = rcu_node_boost_open, .read = seq_read, - .llseek = seq_lseek, + .llseek = no_llseek, .release = single_release, }; -/* - * Create the rcuboost debugfs entry. Standard error return. - */ -static int rcu_boost_trace_create_file(struct dentry *rcudir) -{ - return !debugfs_create_file("rcuboost", 0444, rcudir, NULL, - &rcu_node_boost_fops); -} - -#else /* #ifdef CONFIG_RCU_BOOST */ - -static int rcu_boost_trace_create_file(struct dentry *rcudir) -{ - return 0; /* There cannot be an error if we didn't create it! */ -} - -#endif /* #else #ifdef CONFIG_RCU_BOOST */ +#endif /* #ifdef CONFIG_RCU_BOOST */ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) { @@ -283,8 +261,9 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) struct rcu_node *rnp; gpnum = rsp->gpnum; - seq_printf(m, "%s: c=%lu g=%lu s=%d jfq=%ld j=%x ", - rsp->name, rsp->completed, gpnum, rsp->fqs_state, + seq_printf(m, "c=%ld g=%ld s=%d jfq=%ld j=%x ", + ulong2long(rsp->completed), ulong2long(gpnum), + rsp->fqs_state, (long)(rsp->jiffies_force_qs - jiffies), (int)(jiffies & 0xffff)); seq_printf(m, "nfqs=%lu/nfqsng=%lu(%lu) fqlh=%lu oqlen=%ld/%ld\n", @@ -306,26 +285,24 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp) seq_puts(m, "\n"); } -static int show_rcuhier(struct seq_file *m, void *unused) +static int show_rcuhier(struct seq_file *m, void *v) { - struct rcu_state *rsp; - - for_each_rcu_flavor(rsp) - print_one_rcu_state(m, rsp); + struct rcu_state *rsp = (struct rcu_state *)m->private; + print_one_rcu_state(m, rsp); return 0; } static int rcuhier_open(struct inode *inode, struct file *file) { - return single_open(file, show_rcuhier, NULL); + return single_open(file, show_rcuhier, inode->i_private); } static const struct file_operations rcuhier_fops = { .owner = THIS_MODULE, .open = rcuhier_open, .read = seq_read, - .llseek = seq_lseek, - .release = single_release, + .llseek = no_llseek, + .release = seq_release, }; static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp) @@ -338,42 +315,42 @@ static void show_one_rcugp(struct seq_file *m, struct rcu_state *rsp) struct rcu_node *rnp = &rsp->node[0]; raw_spin_lock_irqsave(&rnp->lock, flags); - completed = rsp->completed; - gpnum = rsp->gpnum; - if (rsp->completed == rsp->gpnum) + completed = ACCESS_ONCE(rsp->completed); + gpnum = ACCESS_ONCE(rsp->gpnum); + if (completed == gpnum) gpage = 0; else gpage = jiffies - rsp->gp_start; gpmax = rsp->gp_max; raw_spin_unlock_irqrestore(&rnp->lock, flags); - seq_printf(m, "%s: completed=%ld gpnum=%lu age=%ld max=%ld\n", - rsp->name, completed, gpnum, gpage, gpmax); + seq_printf(m, "completed=%ld gpnum=%ld age=%ld max=%ld\n", + ulong2long(completed), ulong2long(gpnum), gpage, gpmax); } -static int show_rcugp(struct seq_file *m, void *unused) +static int show_rcugp(struct seq_file *m, void *v) { - struct rcu_state *rsp; - - for_each_rcu_flavor(rsp) - show_one_rcugp(m, rsp); + struct rcu_state *rsp = (struct rcu_state *)m->private; + show_one_rcugp(m, rsp); return 0; } static int rcugp_open(struct inode *inode, struct file *file) { - return single_open(file, show_rcugp, NULL); + return single_open(file, show_rcugp, inode->i_private); } static const struct file_operations rcugp_fops = { .owner = THIS_MODULE, .open = rcugp_open, .read = seq_read, - .llseek = seq_lseek, - .release = single_release, + .llseek = no_llseek, + .release = seq_release, }; static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp) { + if (!rdp->beenonline) + return; seq_printf(m, "%3d%cnp=%ld ", rdp->cpu, cpu_is_offline(rdp->cpu) ? '!' : ' ', @@ -389,34 +366,30 @@ static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp) rdp->n_rp_need_nothing); } -static int show_rcu_pending(struct seq_file *m, void *unused) +static int show_rcu_pending(struct seq_file *m, void *v) { - int cpu; - struct rcu_data *rdp; - struct rcu_state *rsp; - - for_each_rcu_flavor(rsp) { - seq_printf(m, "%s:\n", rsp->name); - for_each_possible_cpu(cpu) { - rdp = per_cpu_ptr(rsp->rda, cpu); - if (rdp->beenonline) - print_one_rcu_pending(m, rdp); - } - } + print_one_rcu_pending(m, (struct rcu_data *)v); return 0; } +static const struct seq_operations rcu_pending_op = { + .start = r_start, + .next = r_next, + .stop = r_stop, + .show = show_rcu_pending, +}; + static int rcu_pending_open(struct inode *inode, struct file *file) { - return single_open(file, show_rcu_pending, NULL); + return r_open(inode, file, &rcu_pending_op); } static const struct file_operations rcu_pending_fops = { .owner = THIS_MODULE, .open = rcu_pending_open, .read = seq_read, - .llseek = seq_lseek, - .release = single_release, + .llseek = no_llseek, + .release = seq_release, }; static int show_rcutorture(struct seq_file *m, void *unused) @@ -446,43 +419,58 @@ static struct dentry *rcudir; static int __init rcutree_trace_init(void) { + struct rcu_state *rsp; struct dentry *retval; + struct dentry *rspdir; rcudir = debugfs_create_dir("rcu", NULL); if (!rcudir) goto free_out; - retval = debugfs_create_file("rcubarrier", 0444, rcudir, - NULL, &rcubarrier_fops); - if (!retval) - goto free_out; - - retval = debugfs_create_file("rcudata", 0444, rcudir, - NULL, &rcudata_fops); - if (!retval) - goto free_out; - - retval = debugfs_create_file("rcudata.csv", 0444, rcudir, - NULL, &rcudata_csv_fops); - if (!retval) - goto free_out; - - if (rcu_boost_trace_create_file(rcudir)) - goto free_out; + for_each_rcu_flavor(rsp) { + rspdir = debugfs_create_dir(rsp->name, rcudir); + if (!rspdir) + goto free_out; + + retval = debugfs_create_file("rcudata", 0444, + rspdir, rsp, &rcudata_fops); + if (!retval) + goto free_out; + + retval = debugfs_create_file("rcuexp", 0444, + rspdir, rsp, &rcuexp_fops); + if (!retval) + goto free_out; + + retval = debugfs_create_file("rcu_pending", 0444, + rspdir, rsp, &rcu_pending_fops); + if (!retval) + goto free_out; + + retval = debugfs_create_file("rcubarrier", 0444, + rspdir, rsp, &rcubarrier_fops); + if (!retval) + goto free_out; - retval = debugfs_create_file("rcugp", 0444, rcudir, NULL, &rcugp_fops); - if (!retval) - goto free_out; +#ifdef CONFIG_RCU_BOOST + if (rsp == &rcu_preempt_state) { + retval = debugfs_create_file("rcuboost", 0444, + rspdir, NULL, &rcu_node_boost_fops); + if (!retval) + goto free_out; + } +#endif - retval = debugfs_create_file("rcuhier", 0444, rcudir, - NULL, &rcuhier_fops); - if (!retval) - goto free_out; + retval = debugfs_create_file("rcugp", 0444, + rspdir, rsp, &rcugp_fops); + if (!retval) + goto free_out; - retval = debugfs_create_file("rcu_pending", 0444, rcudir, - NULL, &rcu_pending_fops); - if (!retval) - goto free_out; + retval = debugfs_create_file("rcuhier", 0444, + rspdir, rsp, &rcuhier_fops); + if (!retval) + goto free_out; + } retval = debugfs_create_file("rcutorture", 0444, rcudir, NULL, &rcutorture_fops); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 68414fa4cd2..6d4569e0924 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8076,3 +8076,9 @@ struct cgroup_subsys cpuacct_subsys = { .base_cftypes = files, }; #endif /* CONFIG_CGROUP_CPUACCT */ + +void dump_cpu_task(int cpu) +{ + pr_info("Task dump for CPU %d:\n", cpu); + sched_show_task(cpu_curr(cpu)); +} diff --git a/kernel/srcu.c b/kernel/srcu.c index de9074047c9..2b859828cdc 100644 --- a/kernel/srcu.c +++ b/kernel/srcu.c @@ -16,8 +16,10 @@ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * Copyright (C) IBM Corporation, 2006 + * Copyright (C) Fujitsu, 2012 * * Author: Paul McKenney <paulmck@us.ibm.com> + * Lai Jiangshan <laijs@cn.fujitsu.com> * * For detailed explanation of Read-Copy Update mechanism see - * Documentation/RCU/ *.txt @@ -96,9 +98,6 @@ static inline void rcu_batch_move(struct rcu_batch *to, struct rcu_batch *from) } } -/* single-thread state-machine */ -static void process_srcu(struct work_struct *work); - static int init_srcu_struct_fields(struct srcu_struct *sp) { sp->completed = 0; @@ -643,7 +642,7 @@ static void srcu_reschedule(struct srcu_struct *sp) /* * This is the work-queue function that handles SRCU grace periods. */ -static void process_srcu(struct work_struct *work) +void process_srcu(struct work_struct *work) { struct srcu_struct *sp; @@ -654,3 +653,4 @@ static void process_srcu(struct work_struct *work) srcu_invoke_callbacks(sp); srcu_reschedule(sp); } +EXPORT_SYMBOL_GPL(process_srcu); |