diff options
author | Ingo Molnar | 2020-10-09 08:21:56 +0200 |
---|---|---|
committer | Ingo Molnar | 2020-10-09 08:21:56 +0200 |
commit | b36c830f8c9b13bfe69b117e879153776c19ad82 (patch) | |
tree | 151b7e91a49ff894e11e0b24c0e8cf9675dd5d91 /kernel/rcu | |
parent | 583090b1b8232e6eae243a9009699666153a13a9 (diff) | |
parent | 6fe208f63a79f4f726f3be2b78ea3dd40487b657 (diff) |
Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull v5.10 RCU changes from Paul E. McKenney:
- Debugging for smp_call_function().
- Strict grace periods for KASAN. The point of this series is to find
RCU-usage bugs, so the corresponding new RCU_STRICT_GRACE_PERIOD
Kconfig option depends on both DEBUG_KERNEL and RCU_EXPERT, and is
further disabled by dfefault. Finally, the help text includes
a goodly list of scary caveats.
- New smp_call_function() torture test.
- Torture-test updates.
- Documentation updates.
- Miscellaneous fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/rcu')
-rw-r--r-- | kernel/rcu/Kconfig | 8 | ||||
-rw-r--r-- | kernel/rcu/Kconfig.debug | 17 | ||||
-rw-r--r-- | kernel/rcu/Makefile | 2 | ||||
-rw-r--r-- | kernel/rcu/rcu_segcblist.c | 10 | ||||
-rw-r--r-- | kernel/rcu/rcuscale.c (renamed from kernel/rcu/rcuperf.c) | 330 | ||||
-rw-r--r-- | kernel/rcu/rcutorture.c | 61 | ||||
-rw-r--r-- | kernel/rcu/refscale.c | 8 | ||||
-rw-r--r-- | kernel/rcu/srcutree.c | 13 | ||||
-rw-r--r-- | kernel/rcu/tree.c | 165 | ||||
-rw-r--r-- | kernel/rcu/tree.h | 2 | ||||
-rw-r--r-- | kernel/rcu/tree_exp.h | 6 | ||||
-rw-r--r-- | kernel/rcu/tree_plugin.h | 40 | ||||
-rw-r--r-- | kernel/rcu/tree_stall.h | 8 | ||||
-rw-r--r-- | kernel/rcu/update.c | 13 |
14 files changed, 395 insertions, 288 deletions
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig index 0ebe15a84985..b71e21f73c40 100644 --- a/kernel/rcu/Kconfig +++ b/kernel/rcu/Kconfig @@ -135,10 +135,12 @@ config RCU_FANOUT config RCU_FANOUT_LEAF int "Tree-based hierarchical RCU leaf-level fanout value" - range 2 64 if 64BIT - range 2 32 if !64BIT + range 2 64 if 64BIT && !RCU_STRICT_GRACE_PERIOD + range 2 32 if !64BIT && !RCU_STRICT_GRACE_PERIOD + range 2 3 if RCU_STRICT_GRACE_PERIOD depends on TREE_RCU && RCU_EXPERT - default 16 + default 16 if !RCU_STRICT_GRACE_PERIOD + default 2 if RCU_STRICT_GRACE_PERIOD help This option controls the leaf-level fanout of hierarchical implementations of RCU, and allows trading off cache misses diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug index 3cf6132a4bb9..1942c1f1bb65 100644 --- a/kernel/rcu/Kconfig.debug +++ b/kernel/rcu/Kconfig.debug @@ -23,7 +23,7 @@ config TORTURE_TEST tristate default n -config RCU_PERF_TEST +config RCU_SCALE_TEST tristate "performance tests for RCU" depends on DEBUG_KERNEL select TORTURE_TEST @@ -114,4 +114,19 @@ config RCU_EQS_DEBUG Say N here if you need ultimate kernel/user switch latencies Say Y if you are unsure +config RCU_STRICT_GRACE_PERIOD + bool "Provide debug RCU implementation with short grace periods" + depends on DEBUG_KERNEL && RCU_EXPERT + default n + select PREEMPT_COUNT if PREEMPT=n + help + Select this option to build an RCU variant that is strict about + grace periods, making them as short as it can. This limits + scalability, destroys real-time response, degrades battery + lifetime and kills performance. Don't try this on large + machines, as in systems with more than about 10 or 20 CPUs. + But in conjunction with tools like KASAN, it can be helpful + when looking for certain types of RCU usage bugs, for example, + too-short RCU read-side critical sections. + endmenu # "RCU Debugging" diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile index 95f5117ef8da..0cfb009a99b9 100644 --- a/kernel/rcu/Makefile +++ b/kernel/rcu/Makefile @@ -11,7 +11,7 @@ obj-y += update.o sync.o obj-$(CONFIG_TREE_SRCU) += srcutree.o obj-$(CONFIG_TINY_SRCU) += srcutiny.o obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o -obj-$(CONFIG_RCU_PERF_TEST) += rcuperf.o +obj-$(CONFIG_RCU_SCALE_TEST) += rcuscale.o obj-$(CONFIG_RCU_REF_SCALE_TEST) += refscale.o obj-$(CONFIG_TREE_RCU) += tree.o obj-$(CONFIG_TINY_RCU) += tiny.o diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c index 9a0f66133b4b..2d2a6b6b9dfb 100644 --- a/kernel/rcu/rcu_segcblist.c +++ b/kernel/rcu/rcu_segcblist.c @@ -475,8 +475,16 @@ bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq) * Also advance to the oldest segment of callbacks whose * ->gp_seq[] completion is at or after that passed in via "seq", * skipping any empty segments. + * + * Note that segment "i" (and any lower-numbered segments + * containing older callbacks) will be unaffected, and their + * grace-period numbers remain unchanged. For example, if i == + * WAIT_TAIL, then neither WAIT_TAIL nor DONE_TAIL will be touched. + * Instead, the CBs in NEXT_TAIL will be merged with those in + * NEXT_READY_TAIL and the grace-period number of NEXT_READY_TAIL + * would be updated. NEXT_TAIL would then be empty. */ - if (++i >= RCU_NEXT_TAIL) + if (rcu_segcblist_restempty(rsclp, i) || ++i >= RCU_NEXT_TAIL) return false; /* diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuscale.c index 21448d3374e2..2819b95479af 100644 --- a/kernel/rcu/rcuperf.c +++ b/kernel/rcu/rcuscale.c @@ -1,6 +1,6 @@ // SPDX-License-Identifier: GPL-2.0+ /* - * Read-Copy Update module-based performance-test facility + * Read-Copy Update module-based scalability-test facility * * Copyright (C) IBM Corporation, 2015 * @@ -44,13 +44,13 @@ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>"); -#define PERF_FLAG "-perf:" -#define PERFOUT_STRING(s) \ - 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) \ - do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0) +#define SCALE_FLAG "-scale:" +#define SCALEOUT_STRING(s) \ + pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s) +#define VERBOSE_SCALEOUT_STRING(s) \ + do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0) +#define VERBOSE_SCALEOUT_ERRSTRING(s) \ + do { if (verbose) pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s); } while (0) /* * The intended use cases for the nreaders and nwriters module parameters @@ -61,25 +61,25 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>"); * nr_cpus for a mixed reader/writer test. * * 2. Specify the nr_cpus kernel boot parameter, but set - * rcuperf.nreaders to zero. This will set nwriters to the + * rcuscale.nreaders to zero. This will set nwriters to the * value specified by nr_cpus for an update-only test. * * 3. Specify the nr_cpus kernel boot parameter, but set - * rcuperf.nwriters to zero. This will set nreaders to the + * rcuscale.nwriters to zero. This will set nreaders to the * value specified by nr_cpus for a read-only test. * * Various other use cases may of course be specified. * * Note that this test's readers are intended only as a test load for - * the writers. The reader performance statistics will be overly + * the writers. The reader scalability statistics will be overly * pessimistic due to the per-critical-section interrupt disabling, * test-end checks, and the pair of calls through pointers. */ #ifdef MODULE -# define RCUPERF_SHUTDOWN 0 +# define RCUSCALE_SHUTDOWN 0 #else -# define RCUPERF_SHUTDOWN 1 +# define RCUSCALE_SHUTDOWN 1 #endif torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives"); @@ -88,16 +88,16 @@ torture_param(bool, gp_exp, false, "Use expedited GP wait primitives"); torture_param(int, holdoff, 10, "Holdoff time before test start (s)"); torture_param(int, nreaders, -1, "Number of RCU reader threads"); torture_param(int, nwriters, -1, "Number of RCU updater threads"); -torture_param(bool, shutdown, RCUPERF_SHUTDOWN, - "Shutdown at end of performance tests."); +torture_param(bool, shutdown, RCUSCALE_SHUTDOWN, + "Shutdown at end of scalability tests."); torture_param(int, verbose, 1, "Enable verbose debugging printk()s"); torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable"); -torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() perf test?"); +torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?"); torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate."); -static char *perf_type = "rcu"; -module_param(perf_type, charp, 0444); -MODULE_PARM_DESC(perf_type, "Type of RCU to performance-test (rcu, srcu, ...)"); +static char *scale_type = "rcu"; +module_param(scale_type, charp, 0444); +MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)"); static int nrealreaders; static int nrealwriters; @@ -107,12 +107,12 @@ static struct task_struct *shutdown_task; static u64 **writer_durations; static int *writer_n_durations; -static atomic_t n_rcu_perf_reader_started; -static atomic_t n_rcu_perf_writer_started; -static atomic_t n_rcu_perf_writer_finished; +static atomic_t n_rcu_scale_reader_started; +static atomic_t n_rcu_scale_writer_started; +static atomic_t n_rcu_scale_writer_finished; static wait_queue_head_t shutdown_wq; -static u64 t_rcu_perf_writer_started; -static u64 t_rcu_perf_writer_finished; +static u64 t_rcu_scale_writer_started; +static u64 t_rcu_scale_writer_finished; static unsigned long b_rcu_gp_test_started; static unsigned long b_rcu_gp_test_finished; static DEFINE_PER_CPU(atomic_t, n_async_inflight); @@ -124,7 +124,7 @@ static DEFINE_PER_CPU(atomic_t, n_async_inflight); * Operations vector for selecting different types of tests. */ -struct rcu_perf_ops { +struct rcu_scale_ops { int ptype; void (*init)(void); void (*cleanup)(void); @@ -140,19 +140,19 @@ struct rcu_perf_ops { const char *name; }; -static struct rcu_perf_ops *cur_ops; +static struct rcu_scale_ops *cur_ops; /* - * Definitions for rcu perf testing. + * Definitions for rcu scalability testing. */ -static int rcu_perf_read_lock(void) __acquires(RCU) +static int rcu_scale_read_lock(void) __acquires(RCU) { rcu_read_lock(); return 0; } -static void rcu_perf_read_unlock(int idx) __releases(RCU) +static void rcu_scale_read_unlock(int idx) __releases(RCU) { rcu_read_unlock(); } @@ -162,15 +162,15 @@ static unsigned long __maybe_unused rcu_no_completed(void) return 0; } -static void rcu_sync_perf_init(void) +static void rcu_sync_scale_init(void) { } -static struct rcu_perf_ops rcu_ops = { +static struct rcu_scale_ops rcu_ops = { .ptype = RCU_FLAVOR, - .init = rcu_sync_perf_init, - .readlock = rcu_perf_read_lock, - .readunlock = rcu_perf_read_unlock, + .init = rcu_sync_scale_init, + .readlock = rcu_scale_read_lock, + .readunlock = rcu_scale_read_unlock, .get_gp_seq = rcu_get_gp_seq, .gp_diff = rcu_seq_diff, .exp_completed = rcu_exp_batches_completed, @@ -182,23 +182,23 @@ static struct rcu_perf_ops rcu_ops = { }; /* - * Definitions for srcu perf testing. + * Definitions for srcu scalability testing. */ -DEFINE_STATIC_SRCU(srcu_ctl_perf); -static struct srcu_struct *srcu_ctlp = &srcu_ctl_perf; +DEFINE_STATIC_SRCU(srcu_ctl_scale); +static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale; -static int srcu_perf_read_lock(void) __acquires(srcu_ctlp) +static int srcu_scale_read_lock(void) __acquires(srcu_ctlp) { return srcu_read_lock(srcu_ctlp); } -static void srcu_perf_read_unlock(int idx) __releases(srcu_ctlp) +static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp) { srcu_read_unlock(srcu_ctlp, idx); } -static unsigned long srcu_perf_completed(void) +static unsigned long srcu_scale_completed(void) { return srcu_batches_completed(srcu_ctlp); } @@ -213,78 +213,78 @@ static void srcu_rcu_barrier(void) srcu_barrier(srcu_ctlp); } -static void srcu_perf_synchronize(void) +static void srcu_scale_synchronize(void) { synchronize_srcu(srcu_ctlp); } -static void srcu_perf_synchronize_expedited(void) +static void srcu_scale_synchronize_expedited(void) { synchronize_srcu_expedited(srcu_ctlp); } -static struct rcu_perf_ops srcu_ops = { +static struct rcu_scale_ops srcu_ops = { .ptype = SRCU_FLAVOR, - .init = rcu_sync_perf_init, - .readlock = srcu_perf_read_lock, - .readunlock = srcu_perf_read_unlock, - .get_gp_seq = srcu_perf_completed, + .init = rcu_sync_scale_init, + .readlock = srcu_scale_read_lock, + .readunlock = srcu_scale_read_unlock, + .get_gp_seq = srcu_scale_completed, .gp_diff = rcu_seq_diff, - .exp_completed = srcu_perf_completed, + .exp_completed = srcu_scale_completed, .async = srcu_call_rcu, .gp_barrier = srcu_rcu_barrier, - .sync = srcu_perf_synchronize, - .exp_sync = srcu_perf_synchronize_expedited, + .sync = srcu_scale_synchronize, + .exp_sync = srcu_scale_synchronize_expedited, .name = "srcu" }; static struct srcu_struct srcud; -static void srcu_sync_perf_init(void) +static void srcu_sync_scale_init(void) { srcu_ctlp = &srcud; init_srcu_struct(srcu_ctlp); } -static void srcu_sync_perf_cleanup(void) +static void srcu_sync_scale_cleanup(void) { cleanup_srcu_struct(srcu_ctlp); } -static struct rcu_perf_ops srcud_ops = { +static struct rcu_scale_ops srcud_ops = { .ptype = SRCU_FLAVOR, - .init = srcu_sync_perf_init, - .cleanup = srcu_sync_perf_cleanup, - .readlock = srcu_perf_read_lock, - .readunlock = srcu_perf_read_unlock, - .get_gp_seq = srcu_perf_completed, + .init = srcu_sync_scale_init, + .cleanup = srcu_sync_scale_cleanup, + .readlock = srcu_scale_read_lock, + .readunlock = srcu_scale_read_unlock, + .get_gp_seq = srcu_scale_completed, .gp_diff = rcu_seq_diff, - .exp_completed = srcu_perf_completed, + .exp_completed = srcu_scale_completed, .async = srcu_call_rcu, .gp_barrier = srcu_rcu_barrier, - .sync = srcu_perf_synchronize, - .exp_sync = srcu_perf_synchronize_expedited, + .sync = srcu_scale_synchronize, + .exp_sync = srcu_scale_synchronize_expedited, .name = "srcud" }; /* - * Definitions for RCU-tasks perf testing. + * Definitions for RCU-tasks scalability testing. */ -static int tasks_perf_read_lock(void) +static int tasks_scale_read_lock(void) { return 0; } -static void tasks_perf_read_unlock(int idx) +static void tasks_scale_read_unlock(int idx) { } -static struct rcu_perf_ops tasks_ops = { +static struct rcu_scale_ops tasks_ops = { .ptype = RCU_TASKS_FLAVOR, - .init = rcu_sync_perf_init, - .readlock = tasks_perf_read_lock, - .readunlock = tasks_perf_read_unlock, + .init = rcu_sync_scale_init, + .readlock = tasks_scale_read_lock, + .readunlock = tasks_scale_read_unlock, .get_gp_seq = rcu_no_completed, .gp_diff = rcu_seq_diff, .async = call_rcu_tasks, @@ -294,7 +294,7 @@ static struct rcu_perf_ops tasks_ops = { .name = "tasks" }; -static unsigned long rcuperf_seq_diff(unsigned long new, unsigned long old) +static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old) { if (!cur_ops->gp_diff) return new - old; @@ -302,60 +302,60 @@ static unsigned long rcuperf_seq_diff(unsigned long new, unsigned long old) } /* - * If performance tests complete, wait for shutdown to commence. + * If scalability tests complete, wait for shutdown to commence. */ -static void rcu_perf_wait_shutdown(void) +static void rcu_scale_wait_shutdown(void) { cond_resched_tasks_rcu_qs(); - if (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters) + if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters) return; while (!torture_must_stop()) schedule_timeout_uninterruptible(1); } /* - * RCU perf reader kthread. Repeatedly does empty RCU read-side critical - * section, minimizing update-side interference. However, the point of - * this test is not to evaluate reader performance, but instead to serve - * as a test load for update-side performance testing. + * RCU scalability reader kthread. Repeatedly does empty RCU read-side + * critical section, minimizing update-side interference. However, the + * point of this test is not to evaluate reader scalability, but instead + * to serve as a test load for update-side scalability testing. */ static int -rcu_perf_reader(void *arg) +rcu_scale_reader(void *arg) { unsigned long flags; int idx; long me = (long)arg; - VERBOSE_PERFOUT_STRING("rcu_perf_reader task started"); + VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started"); set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)); set_user_nice(current, MAX_NICE); - atomic_inc(&n_rcu_perf_reader_started); + atomic_inc(&n_rcu_scale_reader_started); do { local_irq_save(flags); idx = cur_ops->readlock(); cur_ops->readunlock(idx); local_irq_restore(flags); - rcu_perf_wait_shutdown(); + rcu_scale_wait_shutdown(); } while (!torture_must_stop()); - torture_kthread_stopping("rcu_perf_reader"); + torture_kthread_stopping("rcu_scale_reader"); return 0; } /* - * Callback function for asynchronous grace periods from rcu_perf_writer(). + * Callback function for asynchronous grace periods from rcu_scale_writer(). */ -static void rcu_perf_async_cb(struct rcu_head *rhp) +static void rcu_scale_async_cb(struct rcu_head *rhp) { atomic_dec(this_cpu_ptr(&n_async_inflight)); kfree(rhp); } /* - * RCU perf writer kthread. Repeatedly does a grace period. + * RCU scale writer kthread. Repeatedly does a grace period. */ static int -rcu_perf_writer(void *arg) +rcu_scale_writer(void *arg) { int i = 0; int i_max; @@ -366,7 +366,7 @@ rcu_perf_writer(void *arg) u64 *wdp; u64 *wdpp = writer_durations[me]; - VERBOSE_PERFOUT_STRING("rcu_perf_writer task started"); + VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started"); WARN_ON(!wdpp); set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)); sched_set_fifo_low(current); @@ -383,8 +383,8 @@ rcu_perf_writer(void *arg) schedule_timeout_uninterruptible(1); t = ktime_get_mono_fast_ns(); - if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) { - t_rcu_perf_writer_started = t; + if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) { + t_rcu_scale_writer_started = t; if (gp_exp) { b_rcu_gp_test_started = cur_ops->exp_completed() / 2; @@ -404,7 +404,7 @@ retry: rhp = kmalloc(sizeof(*rhp), GFP_KERNEL); if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) { atomic_inc(this_cpu_ptr(&n_async_inflight)); - cur_ops->async(rhp, rcu_perf_async_cb); + cur_ops->async(rhp, rcu_scale_async_cb); rhp = NULL; } else if (!kthread_should_stop()) { cur_ops->gp_barrier(); @@ -421,19 +421,19 @@ retry: *wdp = t - *wdp; i_max = i; if (!started && - atomic_read(&n_rcu_perf_writer_started) >= nrealwriters) + atomic_read(&n_rcu_scale_writer_started) >= nrealwriters) started = true; if (!done && i >= MIN_MEAS) { done = true; sched_set_normal(current, 0); - 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) >= + pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n", + scale_type, SCALE_FLAG, me, MIN_MEAS); + if (atomic_inc_return(&n_rcu_scale_writer_finished) >= nrealwriters) { schedule_timeout_interruptible(10); rcu_ftrace_dump(DUMP_ALL); - PERFOUT_STRING("Test complete"); - t_rcu_perf_writer_finished = t; + SCALEOUT_STRING("Test complete"); + t_rcu_scale_writer_finished = t; if (gp_exp) { b_rcu_gp_test_finished = cur_ops->exp_completed() / 2; @@ -448,30 +448,30 @@ retry: } } if (done && !alldone && - atomic_read(&n_rcu_perf_writer_finished) >= nrealwriters) + atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters) alldone = true; if (started && !alldone && i < MAX_MEAS - 1) i++; - rcu_perf_wait_shutdown(); + rcu_scale_wait_shutdown(); } while (!torture_must_stop()); if (gp_async) { cur_ops->gp_barrier(); } writer_n_durations[me] = i_max; - torture_kthread_stopping("rcu_perf_writer"); + torture_kthread_stopping("rcu_scale_writer"); return 0; } static void -rcu_perf_print_module_parms(struct rcu_perf_ops *cur_ops, const char *tag) +rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag) { - pr_alert("%s" PERF_FLAG + pr_alert("%s" SCALE_FLAG "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n", - perf_type, tag, nrealreaders, nrealwriters, verbose, shutdown); + scale_type, tag, nrealreaders, nrealwriters, verbose, shutdown); } static void -rcu_perf_cleanup(void) +rcu_scale_cleanup(void) { int i; int j; @@ -484,11 +484,11 @@ rcu_perf_cleanup(void) * during the mid-boot phase, so have to wait till the end. */ if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp) - VERBOSE_PERFOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!"); + VERBOSE_SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!"); if (rcu_gp_is_normal() && gp_exp) - VERBOSE_PERFOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!"); + VERBOSE_SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!"); if (gp_exp && gp_async) - VERBOSE_PERFOUT_ERRSTRING("No expedited async GPs, so went with async!"); + VERBOSE_SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!"); if (torture_cleanup_begin()) return; @@ -499,30 +499,30 @@ rcu_perf_cleanup(void) if (reader_tasks) { for (i = 0; i < nrealreaders; i++) - torture_stop_kthread(rcu_perf_reader, + torture_stop_kthread(rcu_scale_reader, reader_tasks[i]); kfree(reader_tasks); } if (writer_tasks) { for (i = 0; i < nrealwriters; i++) { - torture_stop_kthread(rcu_perf_writer, + torture_stop_kthread(rcu_scale_writer, writer_tasks[i]); if (!writer_n_durations) continue; j = writer_n_durations[i]; pr_alert("%s%s writer %d gps: %d\n", - perf_type, PERF_FLAG, i, j); + scale_type, SCALE_FLAG, i, j); ngps += j; } pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n", - perf_type, PERF_FLAG, - t_rcu_perf_writer_started, t_rcu_perf_writer_finished, - t_rcu_perf_writer_finished - - t_rcu_perf_writer_started, + scale_type, SCALE_FLAG, + t_rcu_scale_writer_started, t_rcu_scale_writer_finished, + t_rcu_scale_writer_finished - + t_rcu_scale_writer_started, ngps, - rcuperf_seq_diff(b_rcu_gp_test_finished, - b_rcu_gp_test_started)); + rcuscale_seq_diff(b_rcu_gp_test_finished, + b_rcu_gp_test_started)); for (i = 0; i < nrealwriters; i++) { if (!writer_durations) break; @@ -534,7 +534,7 @@ rcu_perf_cleanup(void) for (j = 0; j <= writer_n_durations[i]; j++) { wdp = &wdpp[j]; pr_alert("%s%s %4d writer-duration: %5d %llu\n", - perf_type, PERF_FLAG, + scale_type, SCALE_FLAG, i, j, *wdp); if (j % 100 == 0) schedule_timeout_uninterruptible(1); @@ -573,22 +573,22 @@ static int compute_real(int n) } /* - * RCU perf shutdown kthread. Just waits to be awakened, then shuts + * RCU scalability shutdown kthread. Just waits to be awakened, then shuts * down system. */ static int -rcu_perf_shutdown(void *arg) +rcu_scale_shutdown(void *arg) { wait_event(shutdown_wq, - atomic_read(&n_rcu_perf_writer_finished) >= nrealwriters); + atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters); smp_mb(); /* Wake before output. */ - rcu_perf_cleanup(); + rcu_scale_cleanup(); kernel_power_off(); return -EINVAL; } /* - * kfree_rcu() performance tests: Start a kfree_rcu() loop on all CPUs for number + * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number * of iterations and measure total time and number of GP for all iterations to complete. */ @@ -598,8 +598,8 @@ torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num alloc static struct task_struct **kfree_reader_tasks; static int kfree_nrealthreads; -static atomic_t n_kfree_perf_thread_started; -static atomic_t n_kfree_perf_thread_ended; +static atomic_t n_kfree_scale_thread_started; +static atomic_t n_kfree_scale_thread_ended; struct kfree_obj { char kfree_obj[8]; @@ -607,7 +607,7 @@ struct kfree_obj { }; static int -kfree_perf_thread(void *arg) +kfree_scale_thread(void *arg) { int i, loop = 0; long me = (long)arg; @@ -615,13 +615,13 @@ kfree_perf_thread(void *arg) u64 start_time, end_time; long long mem_begin, mem_during = 0; - VERBOSE_PERFOUT_STRING("kfree_perf_thread task started"); + VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started"); set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids)); set_user_nice(current, MAX_NICE); start_time = ktime_get_mono_fast_ns(); - if (atomic_inc_return(&n_kfree_perf_thread_started) >= kfree_nrealthreads) { + if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) { if (gp_exp) b_rcu_gp_test_started = cur_ops->exp_completed() / 2; else @@ -646,7 +646,7 @@ kfree_perf_thread(void *arg) cond_resched(); } while (!torture_must_stop() && ++loop < kfree_loops); - if (atomic_inc_return(&n_kfree_perf_thread_ended) >= kfree_nrealthreads) { + if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) { end_time = ktime_get_mono_fast_ns(); if (gp_exp) @@ -656,7 +656,7 @@ kfree_perf_thread(void *arg) pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n", (unsigned long long)(end_time - start_time), kfree_loops, - rcuperf_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started), + rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started), (mem_begin - mem_during) >> (20 - PAGE_SHIFT)); if (shutdown) { @@ -665,12 +665,12 @@ kfree_perf_thread(void *arg) } } - torture_kthread_stopping("kfree_perf_thread"); + torture_kthread_stopping("kfree_scale_thread"); return 0; } static void -kfree_perf_cleanup(void) +kfree_scale_cleanup(void) { int i; @@ -679,7 +679,7 @@ kfree_perf_cleanup(void) if (kfree_reader_tasks) { for (i = 0; i < kfree_nrealthreads; i++) - torture_stop_kthread(kfree_perf_thread, + torture_stop_kthread(kfree_scale_thread, kfree_reader_tasks[i]); kfree(kfree_reader_tasks); } @@ -691,20 +691,20 @@ kfree_perf_cleanup(void) * shutdown kthread. Just waits to be awakened, then shuts down system. */ static int -kfree_perf_shutdown(void *arg) +kfree_scale_shutdown(void *arg) { wait_event(shutdown_wq, - atomic_read(&n_kfree_perf_thread_ended) >= kfree_nrealthreads); + atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads); smp_mb(); /* Wake before output. */ - kfree_perf_cleanup(); + kfree_scale_cleanup(); kernel_power_off(); return -EINVAL; } static int __init -kfree_perf_init(void) +kfree_scale_init(void) { long i; int firsterr = 0; @@ -713,7 +713,7 @@ kfree_perf_init(void) /* Start up the kthreads. */ if (shutdown) { init_waitqueue_head(&shutdown_wq); - firsterr = torture_create_kthread(kfree_perf_shutdown, NULL, + firsterr = torture_create_kthread(kfree_scale_shutdown, NULL, shutdown_task); if (firsterr) goto unwind; @@ -730,13 +730,13 @@ kfree_perf_init(void) } for (i = 0; i < kfree_nrealthreads; i++) { - firsterr = torture_create_kthread(kfree_perf_thread, (void *)i, + firsterr = torture_create_kthread(kfree_scale_thread, (void *)i, kfree_reader_tasks[i]); if (firsterr) goto unwind; } - while (atomic_read(&n_kfree_perf_thread_started) < kfree_nrealthreads) + while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads) schedule_timeout_uninterruptible(1); torture_init_end(); @@ -744,35 +744,35 @@ kfree_perf_init(void) unwind: torture_init_end(); - kfree_perf_cleanup(); + kfree_scale_cleanup(); return firsterr; } static int __init -rcu_perf_init(void) +rcu_scale_init(void) { long i; int firsterr = 0; - static struct rcu_perf_ops *perf_ops[] = { + static struct rcu_scale_ops *scale_ops[] = { &rcu_ops, &srcu_ops, &srcud_ops, &tasks_ops, }; - if (!torture_init_begin(perf_type, verbose)) + if (!torture_init_begin(scale_type, verbose)) return -EBUSY; - /* Process args and tell the world that the perf'er is on the job. */ - for (i = 0; i < ARRAY_SIZE(perf_ops); i++) { - cur_ops = perf_ops[i]; - if (strcmp(perf_type, cur_ops->name) == 0) + /* Process args and announce that the scalability'er is on the job. */ + for (i = 0; i < ARRAY_SIZE(scale_ops); i++) { + cur_ops = scale_ops[i]; + if (strcmp(scale_type, cur_ops->name) == 0) break; } - if (i == ARRAY_SIZE(perf_ops)) { - pr_alert("rcu-perf: invalid perf type: \"%s\"\n", perf_type); - pr_alert("rcu-perf types:"); - for (i = 0; i < ARRAY_SIZE(perf_ops); i++) - pr_cont(" %s", perf_ops[i]->name); + if (i == ARRAY_SIZE(scale_ops)) { + pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type); + pr_alert("rcu-scale types:"); + for (i = 0; i < ARRAY_SIZE(scale_ops); i++) + pr_cont(" %s", scale_ops[i]->name); pr_cont("\n"); - WARN_ON(!IS_MODULE(CONFIG_RCU_PERF_TEST)); + WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST)); firsterr = -EINVAL; cur_ops = NULL; goto unwind; @@ -781,20 +781,20 @@ rcu_perf_init(void) cur_ops->init(); if (kfree_rcu_test) - return kfree_perf_init(); + return kfree_scale_init(); nrealwriters = compute_real(nwriters); nrealreaders = compute_real(nreaders); - atomic_set(&n_rcu_perf_reader_started, 0); - atomic_set(&n_rcu_perf_writer_started, 0); - atomic_set(&n_rcu_perf_writer_finished, 0); - rcu_perf_print_module_parms(cur_ops, "Start of test"); + atomic_set(&n_rcu_scale_reader_started, 0); + atomic_set(&n_rcu_scale_writer_started, 0); + atomic_set(&n_rcu_scale_writer_finished, 0); + rcu_scale_print_module_parms(cur_ops, "Start of test"); /* Start up the kthreads. */ if (shutdown) { init_waitqueue_head(&shutdown_wq); - firsterr = torture_create_kthread(rcu_perf_shutdown, NULL, + firsterr = torture_create_kthread(rcu_scale_shutdown, NULL, shutdown_task); if (firsterr) goto unwind; @@ -803,17 +803,17 @@ rcu_perf_init(void) reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]), GFP_KERNEL); if (reader_tasks == NULL) { - VERBOSE_PERFOUT_ERRSTRING("out of memory"); + VERBOSE_SCALEOUT_ERRSTRING("out of memory"); firsterr = -ENOMEM; goto unwind; } for (i = 0; i < nrealreaders; i++) { - firsterr = torture_create_kthread(rcu_perf_reader, (void *)i, + firsterr = torture_create_kthread(rcu_scale_reader, (void *)i, reader_tasks[i]); if (firsterr) goto unwind; } - while (atomic_read(&n_rcu_perf_reader_started) < nrealreaders) + while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders) schedule_timeout_uninterruptible(1); writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]), GFP_KERNEL); @@ -823,7 +823,7 @@ rcu_perf_init(void) kcalloc(nrealwriters, sizeof(*writer_n_durations), GFP_KERNEL); if (!writer_tasks || !writer_durations || !writer_n_durations) { - VERBOSE_PERFOUT_ERRSTRING("out of memory"); + VERBOSE_SCALEOUT_ERRSTRING("out of memory"); firsterr = -ENOMEM; goto unwind; } @@ -835,7 +835,7 @@ rcu_perf_init(void) firsterr = -ENOMEM; goto unwind; } - firsterr = torture_create_kthread(rcu_perf_writer, (void *)i, + firsterr = torture_create_kthread(rcu_scale_writer, (void *)i, writer_tasks[i]); if (firsterr) goto unwind; @@ -845,9 +845,9 @@ rcu_perf_init(void) unwind: torture_init_end(); - rcu_perf_cleanup(); + rcu_scale_cleanup(); return firsterr; } -module_init(rcu_perf_init); -module_exit(rcu_perf_cleanup); +module_init(rcu_scale_init); +module_exit(rcu_scale_cleanup); diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index f453bf8d2f1e..916ea4f66e4b 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -52,19 +52,6 @@ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>"); -#ifndef data_race -#define data_race(expr) \ - ({ \ - expr; \ - }) -#endif -#ifndef ASSERT_EXCLUSIVE_WRITER -#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0) -#endif -#ifndef ASSERT_EXCLUSIVE_ACCESS -#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0) -#endif - /* Bits for ->extendables field, extendables param, and related definitions. */ #define RCUTORTURE_RDR_SHIFT 8 /* Put SRCU index in upper bits. */ #define RCUTORTURE_RDR_MASK ((1 << RCUTORTURE_RDR_SHIFT) - 1) @@ -100,6 +87,7 @@ torture_param(bool, gp_normal, false, "Use normal (non-expedited) GP wait primitives"); torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives"); torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers"); +torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers"); torture_param(int, n_barrier_cbs, 0, "# of callbacks/kthreads for barrier testing"); torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads"); @@ -185,6 +173,7 @@ static long n_barrier_successes; /* did rcu_barrier test succeed? */ static unsigned long n_read_exits; static struct list_head rcu_torture_removed; static unsigned long shutdown_jiffies; +static unsigned long start_gp_seq; static int rcu_torture_writer_state; #define RTWS_FIXED_DELAY 0 @@ -1413,6 +1402,9 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp) preempt_enable(); rcutorture_one_extend(&readstate, 0, trsp, rtrsp); WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK); + // This next splat is expected behavior if leakpointer, especially + // for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels. + WARN_ON_ONCE(leakpointer && READ_ONCE(p->rtort_pipe_count) > 1); /* If error or close call, record the sequence of reader protections. */ if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) { @@ -1808,6 +1800,7 @@ struct rcu_fwd { unsigned long rcu_launder_gp_seq_start; }; +static DEFINE_MUTEX(rcu_fwd_mutex); static struct rcu_fwd *rcu_fwds; static bool rcu_fwd_emergency_stop; @@ -2074,8 +2067,14 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp) static int rcutorture_oom_notify(struct notifier_block *self, unsigned long notused, void *nfreed) { - struct rcu_fwd *rfp = rcu_fwds; + struct rcu_fwd *rfp; + mutex_lock(&rcu_fwd_mutex); + rfp = rcu_fwds; + if (!rfp) { + mutex_unlock(&rcu_fwd_mutex); + return NOTIFY_OK; + } WARN(1, "%s invoked upon OOM during forward-progress testing.\n", __func__); rcu_torture_fwd_cb_hist(rfp); @@ -2093,6 +2092,7 @@ static int rcutorture_oom_notify(struct notifier_block *self, smp_mb(); /* Frees before return to avoid redoing OOM. */ (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */ pr_info("%s returning after OOM processing.\n", __func__); + mutex_unlock(&rcu_fwd_mutex); return NOTIFY_OK; } @@ -2114,13 +2114,11 @@ static int rcu_torture_fwd_prog(void *args) do { schedule_timeout_interruptible(fwd_progress_holdoff * HZ); WRITE_ONCE(rcu_fwd_emergency_stop, false); - register_oom_notifier(&rcutorture_oom_nb); if (!IS_ENABLED(CONFIG_TINY_RCU) || rcu_inkernel_boot_has_ended()) rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries); if (rcu_inkernel_boot_has_ended()) rcu_torture_fwd_prog_cr(rfp); - unregister_oom_notifier(&rcutorture_oom_nb); /* Avoid slow periods, better to test when busy. */ stutter_wait("rcu_torture_fwd_prog"); @@ -2160,9 +2158,26 @@ static int __init rcu_torture_fwd_prog_init(void) return -ENOMEM; spin_lock_init(&rfp->rcu_fwd_lock); rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head; + mutex_lock(&rcu_fwd_mutex); + rcu_fwds = rfp; + mutex_unlock(&rcu_fwd_mutex); + register_oom_notifier(&rcutorture_oom_nb); return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task); } +static void rcu_torture_fwd_prog_cleanup(void) +{ + struct rcu_fwd *rfp; + + torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task); + rfp = rcu_fwds; + mutex_lock(&rcu_fwd_mutex); + rcu_fwds = NULL; + mutex_unlock(&rcu_fwd_mutex); + unregister_oom_notifier(&rcutorture_oom_nb); + kfree(rfp); +} + /* Callback function for RCU barrier testing. */ static void rcu_torture_barrier_cbf(struct rcu_head *rcu) { @@ -2460,7 +2475,7 @@ rcu_torture_cleanup(void) show_rcu_gp_kthreads(); rcu_torture_read_exit_cleanup(); rcu_torture_barrier_cleanup(); - torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task); + rcu_torture_fwd_prog_cleanup(); torture_stop_kthread(rcu_torture_stall, stall_task); torture_stop_kthread(rcu_torture_writer, writer_task); @@ -2482,8 +2497,9 @@ rcu_torture_cleanup(void) rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq); srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq); - pr_alert("%s: End-test grace-period state: g%lu f%#x\n", - cur_ops->name, gp_seq, flags); + pr_alert("%s: End-test grace-period state: g%ld f%#x total-gps=%ld\n", + cur_ops->name, (long)gp_seq, flags, + rcutorture_seq_diff(gp_seq, start_gp_seq)); torture_stop_kthread(rcu_torture_stats, stats_task); torture_stop_kthread(rcu_torture_fqs, fqs_task); if (rcu_torture_can_boost()) @@ -2607,6 +2623,8 @@ rcu_torture_init(void) long i; int cpu; int firsterr = 0; + int flags = 0; + unsigned long gp_seq = 0; static struct rcu_torture_ops *torture_ops[] = { &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops, &busted_srcud_ops, &tasks_ops, &tasks_rude_ops, @@ -2649,6 +2667,11 @@ rcu_torture_init(void) nrealreaders = 1; } rcu_torture_print_module_parms(cur_ops, "Start of test"); + rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq); + srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq); + start_gp_seq = gp_seq; + pr_alert("%s: Start-test grace-period state: g%ld f%#x\n", + cur_ops->name, (long)gp_seq, flags); /* Set up the freelist. */ diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c index d9291f883b54..952595c678b3 100644 --- a/kernel/rcu/refscale.c +++ b/kernel/rcu/refscale.c @@ -546,9 +546,11 @@ static int main_func(void *arg) // Print the average of all experiments SCALEOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n"); - buf[0] = 0; - strcat(buf, "\n"); - strcat(buf, "Runs\tTime(ns)\n"); + if (!errexit) { + buf[0] = 0; + strcat(buf, "\n"); + strcat(buf, "Runs\tTime(ns)\n"); + } for (exp = 0; exp < nruns; exp++) { u64 avg; diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index c100acf332ed..c13348ee80a5 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -29,19 +29,6 @@ #include "rcu.h" #include "rcu_segcblist.h" -#ifndef data_race -#define data_race(expr) \ - ({ \ - expr; \ - }) -#endif -#ifndef ASSERT_EXCLUSIVE_WRITER -#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0) -#endif -#ifndef ASSERT_EXCLUSIVE_ACCESS -#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0) -#endif - /* Holdoff in nanoseconds for auto-expediting. */ #define DEFAULT_SRCU_EXP_HOLDOFF (25 * 1000) static ulong exp_holdoff = DEFAULT_SRCU_EXP_HOLDOFF; diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index f78ee759af9c..a71c0799bd34 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -70,19 +70,6 @@ #endif #define MODULE_PARAM_PREFIX "rcutree." -#ifndef data_race -#define data_race(expr) \ - ({ \ - expr; \ - }) -#endif -#ifndef ASSERT_EXCLUSIVE_WRITER -#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0) -#endif -#ifndef ASSERT_EXCLUSIVE_ACCESS -#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0) -#endif - /* Data structures. */ /* @@ -178,6 +165,12 @@ module_param(gp_init_delay, int, 0444); static int gp_cleanup_delay; module_param(gp_cleanup_delay, int, 0444); +// Add delay to rcu_read_unlock() for strict grace periods. +static int rcu_unlock_delay; +#ifdef CONFIG_RCU_STRICT_GRACE_PERIOD +module_param(rcu_unlock_delay, int, 0444); +#endif + /* * This rcu parameter is runtime-read-only. It reflects * a minimum allowed number of objects which can be cached @@ -468,24 +461,25 @@ static int rcu_is_cpu_rrupt_from_idle(void) return __this_cpu_read(rcu_data.dynticks_nesting) == 0; } -#define DEFAULT_RCU_BLIMIT 10 /* Maximum callbacks per rcu_do_batch ... */ -#define DEFAULT_MAX_RCU_BLIMIT 10000 /* ... even during callback flood. */ +#define DEFAULT_RCU_BLIMIT (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ? 1000 : 10) + // Maximum callbacks per rcu_do_batch ... +#define DEFAULT_MAX_RCU_BLIMIT 10000 // ... even during callback flood. static long blimit = DEFAULT_RCU_BLIMIT; -#define DEFAULT_RCU_QHIMARK 10000 /* If this many pending, ignore blimit. */ +#define DEFAULT_RCU_QHIMARK 10000 // If this many pending, ignore blimit. static long qhimark = DEFAULT_RCU_QHIMARK; -#define DEFAULT_RCU_QLOMARK 100 /* Once only this many pending, use blimit. */ +#define DEFAULT_RCU_QLOMARK 100 // Once only this many pending, use blimit. static long qlowmark = DEFAULT_RCU_QLOMARK; #define DEFAULT_RCU_QOVLD_MULT 2 #define DEFAULT_RCU_QOVLD (DEFAULT_RCU_QOVLD_MULT * DEFAULT_RCU_QHIMARK) -static long qovld = DEFAULT_RCU_QOVLD; /* If this many pending, hammer QS. */ -static long qovld_calc = -1; /* No pre-initialization lock acquisitions! */ +static long qovld = DEFAULT_RCU_QOVLD; // If this many pending, hammer QS. +static long qovld_calc = -1; // No pre-initialization lock acquisitions! module_param(blimit, long, 0444); module_param(qhimark, long, 0444); module_param(qlowmark, long, 0444); module_param(qovld, long, 0444); -static ulong jiffies_till_first_fqs = ULONG_MAX; +static ulong jiffies_till_first_fqs = IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ? 0 : ULONG_MAX; static ulong jiffies_till_next_fqs = ULONG_MAX; static bool rcu_kick_kthreads; static int rcu_divisor = 7; @@ -1092,11 +1086,6 @@ static void rcu_disable_urgency_upon_qs(struct rcu_data *rdp) } } -noinstr bool __rcu_is_watching(void) -{ - return !rcu_dynticks_curr_cpu_in_eqs(); -} - /** * rcu_is_watching - see if RCU thinks that the current CPU is not idle * @@ -1229,13 +1218,28 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) return 1; } - /* If waiting too long on an offline CPU, complain. */ - if (!(rdp->grpmask & rcu_rnp_online_cpus(rnp)) && - time_after(jiffies, rcu_state.gp_start + HZ)) { + /* + * Complain if a CPU that is considered to be offline from RCU's + * perspective has not yet reported a quiescent state. After all, + * the offline CPU should have reported a quiescent state during + * the CPU-offline process, or, failing that, by rcu_gp_init() + * if it ran concurrently with either the CPU going offline or the + * last task on a leaf rcu_node structure exiting its RCU read-side + * critical section while all CPUs corresponding to that structure + * are offline. This added warning detects bugs in any of these + * code paths. + * + * The rcu_node structure's ->lock is held here, which excludes + * the relevant portions the CPU-hotplug code, the grace-period + * initialization code, and the rcu_read_unlock() code paths. + * + * For more detail, please refer to the "Hotplug CPU" section + * of RCU's Requirements documentation. + */ + if (WARN_ON_ONCE(!(rdp->grpmask & rcu_rnp_online_cpus(rnp)))) { bool onl; struct rcu_node *rnp1; - WARN_ON(1); /* Offline CPUs are supposed to report QS! */ pr_info("%s: grp: %d-%d level: %d ->gp_seq %ld ->completedqs %ld\n", __func__, rnp->grplo, rnp->grphi, rnp->level, (long)rnp->gp_seq, (long)rnp->completedqs); @@ -1498,9 +1502,10 @@ static bool rcu_accelerate_cbs(struct rcu_node *rnp, struct rcu_data *rdp) /* Trace depending on how much we were able to accelerate. */ if (rcu_segcblist_restempty(&rdp->cblist, RCU_WAIT_TAIL)) - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccWaitCB")); + trace_rcu_grace_period(rcu_state.name, gp_seq_req, TPS("AccWaitCB")); else - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccReadyCB")); + trace_rcu_grace_period(rcu_state.name, gp_seq_req, TPS("AccReadyCB")); + return ret; } @@ -1576,6 +1581,19 @@ static void __maybe_unused rcu_advance_cbs_nowake(struct rcu_node *rnp, } /* + * In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels, attempt to generate a + * quiescent state. This is intended to be invoked when the CPU notices + * a new grace period. + */ +static void rcu_strict_gp_check_qs(void) +{ + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) { + rcu_read_lock(); + rcu_read_unlock(); + } +} + +/* * Update CPU-local rcu_data state to record the beginnings and ends of * grace periods. The caller must hold the ->lock of the leaf rcu_node * structure corresponding to the current CPU, and must have irqs disabled. @@ -1645,6 +1663,7 @@ static void note_gp_changes(struct rcu_data *rdp) } needwake = __note_gp_changes(rnp, rdp); raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + rcu_strict_gp_check_qs(); if (needwake) rcu_gp_kthread_wake(); } @@ -1683,6 +1702,15 @@ static void rcu_gp_torture_wait(void) } /* + * Handler for on_each_cpu() to invoke the target CPU's RCU core + * processing. + */ +static void rcu_strict_gp_boundary(void *unused) +{ + invoke_rcu_core(); +} + +/* * Initialize a new grace period. Return false if no grace period required. */ static bool rcu_gp_init(void) @@ -1720,10 +1748,13 @@ static bool rcu_gp_init(void) raw_spin_unlock_irq_rcu_node(rnp); /* - * Apply per-leaf buffered online and offline operations to the - * rcu_node tree. Note that this new grace period need not wait - * for subsequent online CPUs, and that quiescent-state forcing - * will handle subsequent offline CPUs. + * Apply per-leaf buffered online and offline operations to + * the rcu_node tree. Note that this new grace period need not + * wait for subsequent online CPUs, and that RCU hooks in the CPU + * offlining path, when combined with checks in this function, + * will handle CPUs that are currently going offline or that will + * go offline later. Please also refer to "Hotplug CPU" section + * of RCU's Requirements documentation. */ rcu_state.gp_state = RCU_GP_ONOFF; rcu_for_each_leaf_node(rnp) { @@ -1810,6 +1841,10 @@ static bool rcu_gp_init(void) WRITE_ONCE(rcu_state.gp_activity, jiffies); } + // If strict, make all CPUs aware of new grace period. + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) + on_each_cpu(rcu_strict_gp_boundary, NULL, 0); + return true; } @@ -1898,7 +1933,7 @@ static void rcu_gp_fqs_loop(void) break; /* If time for quiescent-state forcing, do it. */ if (!time_after(rcu_state.jiffies_force_qs, jiffies) || - (gf & RCU_GP_FLAG_FQS)) { + (gf & (RCU_GP_FLAG_FQS | RCU_GP_FLAG_OVLD))) { trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("fqsstart")); rcu_gp_fqs(first_gp_fqs); @@ -2026,6 +2061,10 @@ static void rcu_gp_cleanup(void) rcu_state.gp_flags & RCU_GP_FLAG_INIT); } raw_spin_unlock_irq_rcu_node(rnp); + + // If strict, make all CPUs aware of the end of the old grace period. + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) + on_each_cpu(rcu_strict_gp_boundary, NULL, 0); } /* @@ -2204,7 +2243,7 @@ rcu_report_unblock_qs_rnp(struct rcu_node *rnp, unsigned long flags) * structure. This must be called from the specified CPU. */ static void -rcu_report_qs_rdp(int cpu, struct rcu_data *rdp) +rcu_report_qs_rdp(struct rcu_data *rdp) { unsigned long flags; unsigned long mask; @@ -2213,6 +2252,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_data *rdp) rcu_segcblist_is_offloaded(&rdp->cblist); struct rcu_node *rnp; + WARN_ON_ONCE(rdp->cpu != smp_processor_id()); rnp = rdp->mynode; raw_spin_lock_irqsave_rcu_node(rnp, flags); if (rdp->cpu_no_qs.b.norm || rdp->gp_seq != rnp->gp_seq || @@ -2229,8 +2269,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_data *rdp) return; } mask = rdp->grpmask; - if (rdp->cpu == smp_processor_id()) - rdp->core_needs_qs = false; + rdp->core_needs_qs = false; if ((rnp->qsmask & mask) == 0) { raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } else { @@ -2279,7 +2318,7 @@ rcu_check_quiescent_state(struct rcu_data *rdp) * Tell RCU we are done (but rcu_report_qs_rdp() will be the * judge of that). */ - rcu_report_qs_rdp(rdp->cpu, rdp); + rcu_report_qs_rdp(rdp); } /* @@ -2376,6 +2415,7 @@ int rcutree_dead_cpu(unsigned int cpu) */ static void rcu_do_batch(struct rcu_data *rdp) { + int div; unsigned long flags; const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) && rcu_segcblist_is_offloaded(&rdp->cblist); @@ -2404,9 +2444,15 @@ static void rcu_do_batch(struct rcu_data *rdp) rcu_nocb_lock(rdp); WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); pending = rcu_segcblist_n_cbs(&rdp->cblist); - bl = max(rdp->blimit, pending >> rcu_divisor); - if (unlikely(bl > 100)) - tlimit = local_clock() + rcu_resched_ns; + div = READ_ONCE(rcu_divisor); + div = div < 0 ? 7 : div > sizeof(long) * 8 - 2 ? sizeof(long) * 8 - 2 : div; + bl = max(rdp->blimit, pending >> div); + if (unlikely(bl > 100)) { + long rrn = READ_ONCE(rcu_resched_ns); + + rrn = rrn < NSEC_PER_MSEC ? NSEC_PER_MSEC : rrn > NSEC_PER_SEC ? NSEC_PER_SEC : rrn; + tlimit = local_clock() + rrn; + } trace_rcu_batch_start(rcu_state.name, rcu_segcblist_n_cbs(&rdp->cblist), bl); rcu_segcblist_extract_done_cbs(&rdp->cblist, &rcl); @@ -2547,8 +2593,7 @@ static void force_qs_rnp(int (*f)(struct rcu_data *rdp)) raw_spin_lock_irqsave_rcu_node(rnp, flags); rcu_state.cbovldnext |= !!rnp->cbovldmask; if (rnp->qsmask == 0) { - if (!IS_ENABLED(CONFIG_PREEMPT_RCU) || - rcu_preempt_blocked_readers_cgp(rnp)) { + if (rcu_preempt_blocked_readers_cgp(rnp)) { /* * No point in scanning bits because they * are all zero. But we might need to @@ -2616,6 +2661,14 @@ void rcu_force_quiescent_state(void) } EXPORT_SYMBOL_GPL(rcu_force_quiescent_state); +// Workqueue handler for an RCU reader for kernels enforcing struct RCU +// grace periods. +static void strict_work_handler(struct work_struct *work) +{ + rcu_read_lock(); + rcu_read_unlock(); +} + /* Perform RCU core processing work for the current CPU. */ static __latent_entropy void rcu_core(void) { @@ -2660,6 +2713,10 @@ static __latent_entropy void rcu_core(void) /* Do any needed deferred wakeups of rcuo kthreads. */ do_nocb_deferred_wakeup(rdp); trace_rcu_utilization(TPS("End RCU core")); + + // If strict GPs, schedule an RCU reader in a clean environment. + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) + queue_work_on(rdp->cpu, rcu_gp_wq, &rdp->strict_work); } static void rcu_core_si(struct softirq_action *h) @@ -3445,7 +3502,7 @@ kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) unsigned long count = 0; /* Snapshot count of all CPUs */ - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); count += READ_ONCE(krcp->count); @@ -3460,7 +3517,7 @@ kfree_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) int cpu, freed = 0; unsigned long flags; - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { int count; struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); @@ -3493,7 +3550,7 @@ void __init kfree_rcu_scheduler_running(void) int cpu; unsigned long flags; - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); raw_spin_lock_irqsave(&krcp->lock, flags); @@ -3857,6 +3914,7 @@ rcu_boot_init_percpu_data(int cpu) /* Set up local state, ensuring consistent view of global state. */ rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu); + INIT_WORK(&rdp->strict_work, strict_work_handler); WARN_ON_ONCE(rdp->dynticks_nesting != 1); WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp))); rdp->rcu_ofl_gp_seq = rcu_state.gp_seq; @@ -3975,8 +4033,6 @@ int rcutree_offline_cpu(unsigned int cpu) return 0; } -static DEFINE_PER_CPU(int, rcu_cpu_started); - /* * 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 @@ -3996,12 +4052,11 @@ void rcu_cpu_starting(unsigned int cpu) struct rcu_node *rnp; bool newcpu; - if (per_cpu(rcu_cpu_started, cpu)) + rdp = per_cpu_ptr(&rcu_data, cpu); + if (rdp->cpu_started) return; + rdp->cpu_started = true; - per_cpu(rcu_cpu_started, cpu) = 1; - - rdp = per_cpu_ptr(&rcu_data, cpu); rnp = rdp->mynode; mask = rdp->grpmask; raw_spin_lock_irqsave_rcu_node(rnp, flags); @@ -4061,7 +4116,7 @@ void rcu_report_dead(unsigned int cpu) raw_spin_unlock_irqrestore_rcu_node(rnp, flags); raw_spin_unlock(&rcu_state.ofl_lock); - per_cpu(rcu_cpu_started, cpu) = 0; + rdp->cpu_started = false; } /* diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index c96ae351688b..e4f66b8f7c47 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -156,6 +156,7 @@ struct rcu_data { bool beenonline; /* CPU online at least once. */ bool gpwrap; /* Possible ->gp_seq wrap. */ bool exp_deferred_qs; /* This CPU awaiting a deferred QS? */ + bool cpu_started; /* RCU watching this onlining CPU. */ struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ unsigned long grpmask; /* Mask to apply to leaf qsmask. */ unsigned long ticks_this_gp; /* The number of scheduling-clock */ @@ -164,6 +165,7 @@ struct rcu_data { /* period it is aware of. */ struct irq_work defer_qs_iw; /* Obtain later scheduler attention. */ bool defer_qs_iw_pending; /* Scheduler attention pending? */ + struct work_struct strict_work; /* Schedule readers for strict GPs. */ /* 2) batch handling */ struct rcu_segcblist cblist; /* Segmented callback list, with */ diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 1888c0eb1216..8760b6ead770 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -732,11 +732,9 @@ static void rcu_exp_need_qs(void) /* Invoked on each online non-idle CPU for expedited quiescent state. */ static void rcu_exp_handler(void *unused) { - struct rcu_data *rdp; - struct rcu_node *rnp; + struct rcu_data *rdp = this_cpu_ptr(&rcu_data); + struct rcu_node *rnp = rdp->mynode; - rdp = this_cpu_ptr(&rcu_data); - rnp = rdp->mynode; if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) || __this_cpu_read(rcu_data.cpu_no_qs.b.exp)) return; diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 982fc5be5269..fd8a52e9a887 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -36,6 +36,8 @@ static void __init rcu_bootup_announce_oddness(void) pr_info("\tRCU dyntick-idle grace-period acceleration is enabled.\n"); if (IS_ENABLED(CONFIG_PROVE_RCU)) pr_info("\tRCU lockdep checking is enabled.\n"); + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) + pr_info("\tRCU strict (and thus non-scalable) grace periods enabled.\n"); if (RCU_NUM_LVLS >= 4) pr_info("\tFour(or more)-level hierarchy is enabled.\n"); if (RCU_FANOUT_LEAF != 16) @@ -374,6 +376,8 @@ void __rcu_read_lock(void) rcu_preempt_read_enter(); if (IS_ENABLED(CONFIG_PROVE_LOCKING)) WARN_ON_ONCE(rcu_preempt_depth() > RCU_NEST_PMAX); + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) && rcu_state.gp_kthread) + WRITE_ONCE(current->rcu_read_unlock_special.b.need_qs, true); barrier(); /* critical section after entry code. */ } EXPORT_SYMBOL_GPL(__rcu_read_lock); @@ -455,8 +459,14 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags) return; } t->rcu_read_unlock_special.s = 0; - if (special.b.need_qs) - rcu_qs(); + if (special.b.need_qs) { + if (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD)) { + rcu_report_qs_rdp(rdp); + udelay(rcu_unlock_delay); + } else { + rcu_qs(); + } + } /* * Respond to a request by an expedited grace period for a @@ -769,6 +779,24 @@ dump_blkd_tasks(struct rcu_node *rnp, int ncheck) #else /* #ifdef CONFIG_PREEMPT_RCU */ /* + * If strict grace periods are enabled, and if the calling + * __rcu_read_unlock() marks the beginning of a quiescent state, immediately + * report that quiescent state and, if requested, spin for a bit. + */ +void rcu_read_unlock_strict(void) +{ + struct rcu_data *rdp; + + if (!IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) || + irqs_disabled() || preempt_count() || !rcu_state.gp_kthread) + return; + rdp = this_cpu_ptr(&rcu_data); + rcu_report_qs_rdp(rdp); + udelay(rcu_unlock_delay); +} +EXPORT_SYMBOL_GPL(rcu_read_unlock_strict); + +/* * Tell them what RCU they are running. */ static void __init rcu_bootup_announce(void) @@ -1926,6 +1954,7 @@ static void nocb_gp_wait(struct rcu_data *my_rdp) * nearest grace period (if any) to wait for next. The CB kthreads * and the global grace-period kthread are awakened if needed. */ + WARN_ON_ONCE(my_rdp->nocb_gp_rdp != my_rdp); for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_cb_rdp) { trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Check")); rcu_nocb_lock_irqsave(rdp, flags); @@ -2411,13 +2440,12 @@ static void show_rcu_nocb_state(struct rcu_data *rdp) return; waslocked = raw_spin_is_locked(&rdp->nocb_gp_lock); - wastimer = timer_pending(&rdp->nocb_timer); + wastimer = timer_pending(&rdp->nocb_bypass_timer); wassleep = swait_active(&rdp->nocb_gp_wq); - if (!rdp->nocb_defer_wakeup && !rdp->nocb_gp_sleep && - !waslocked && !wastimer && !wassleep) + if (!rdp->nocb_gp_sleep && !waslocked && !wastimer && !wassleep) return; /* Nothing untowards. */ - pr_info(" !!! %c%c%c%c %c\n", + pr_info(" nocb GP activity on CB-only CPU!!! %c%c%c%c %c\n", "lL"[waslocked], "dD"[!!rdp->nocb_defer_wakeup], "tT"[wastimer], diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index b5d3b4794db4..0fde39b8daab 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -158,7 +158,7 @@ static void rcu_stall_kick_kthreads(void) { unsigned long j; - if (!rcu_kick_kthreads) + if (!READ_ONCE(rcu_kick_kthreads)) return; j = READ_ONCE(rcu_state.jiffies_kick_kthreads); if (time_after(jiffies, j) && rcu_state.gp_kthread && @@ -580,7 +580,7 @@ static void check_cpu_stall(struct rcu_data *rdp) unsigned long js; struct rcu_node *rnp; - if ((rcu_stall_is_suppressed() && !rcu_kick_kthreads) || + if ((rcu_stall_is_suppressed() && !READ_ONCE(rcu_kick_kthreads)) || !rcu_gp_in_progress()) return; rcu_stall_kick_kthreads(); @@ -623,7 +623,7 @@ static void check_cpu_stall(struct rcu_data *rdp) /* We haven't checked in, so go dump stack. */ print_cpu_stall(gps); - if (rcu_cpu_stall_ftrace_dump) + if (READ_ONCE(rcu_cpu_stall_ftrace_dump)) rcu_ftrace_dump(DUMP_ALL); } else if (rcu_gp_in_progress() && @@ -632,7 +632,7 @@ static void check_cpu_stall(struct rcu_data *rdp) /* They had a few time units to dump stack, so complain. */ print_other_cpu_stall(gs2, gps); - if (rcu_cpu_stall_ftrace_dump) + if (READ_ONCE(rcu_cpu_stall_ftrace_dump)) rcu_ftrace_dump(DUMP_ALL); } } diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 2de49b5d8dd2..5f7713a27dbb 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -53,19 +53,6 @@ #endif #define MODULE_PARAM_PREFIX "rcupdate." -#ifndef data_race -#define data_race(expr) \ - ({ \ - expr; \ - }) -#endif -#ifndef ASSERT_EXCLUSIVE_WRITER -#define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0) -#endif -#ifndef ASSERT_EXCLUSIVE_ACCESS -#define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0) -#endif - #ifndef CONFIG_TINY_RCU module_param(rcu_expedited, int, 0); module_param(rcu_normal, int, 0); |