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-rw-r--r--kernel/rcu/Kconfig.debug11
-rw-r--r--kernel/rcu/rcuperf.c10
-rw-r--r--kernel/rcu/rcutorture.c29
-rw-r--r--kernel/rcu/tree_plugin.h21
-rw-r--r--kernel/rcu/update.c100
5 files changed, 110 insertions, 61 deletions
diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug
index 5ec3ea4028e2..4aa02eee8f6c 100644
--- a/kernel/rcu/Kconfig.debug
+++ b/kernel/rcu/Kconfig.debug
@@ -8,6 +8,17 @@ menu "RCU Debugging"
config PROVE_RCU
def_bool PROVE_LOCKING
+config PROVE_RCU_LIST
+ bool "RCU list lockdep debugging"
+ depends on PROVE_RCU && RCU_EXPERT
+ default n
+ help
+ Enable RCU lockdep checking for list usages. By default it is
+ turned off since there are several list RCU users that still
+ need to be converted to pass a lockdep expression. To prevent
+ false-positive splats, we keep it default disabled but once all
+ users are converted, we can remove this config option.
+
config TORTURE_TEST
tristate
default n
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index 7a6890b23c5f..5a879d073c1c 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -89,7 +89,7 @@ torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable
static char *perf_type = "rcu";
module_param(perf_type, charp, 0444);
-MODULE_PARM_DESC(perf_type, "Type of RCU to performance-test (rcu, rcu_bh, ...)");
+MODULE_PARM_DESC(perf_type, "Type of RCU to performance-test (rcu, srcu, ...)");
static int nrealreaders;
static int nrealwriters;
@@ -375,6 +375,14 @@ rcu_perf_writer(void *arg)
if (holdoff)
schedule_timeout_uninterruptible(holdoff * HZ);
+ /*
+ * Wait until rcu_end_inkernel_boot() is called for normal GP tests
+ * so that RCU is not always expedited for normal GP tests.
+ * The system_state test is approximate, but works well in practice.
+ */
+ while (!gp_exp && system_state != SYSTEM_RUNNING)
+ 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;
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index fce4e7e6f502..b22947324423 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -161,6 +161,7 @@ static atomic_long_t n_rcu_torture_timers;
static long n_barrier_attempts;
static long n_barrier_successes; /* did rcu_barrier test succeed? */
static struct list_head rcu_torture_removed;
+static unsigned long shutdown_jiffies;
static int rcu_torture_writer_state;
#define RTWS_FIXED_DELAY 0
@@ -228,6 +229,15 @@ static u64 notrace rcu_trace_clock_local(void)
}
#endif /* #else #ifdef CONFIG_RCU_TRACE */
+/*
+ * Stop aggressive CPU-hog tests a bit before the end of the test in order
+ * to avoid interfering with test shutdown.
+ */
+static bool shutdown_time_arrived(void)
+{
+ return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
+}
+
static unsigned long boost_starttime; /* jiffies of next boost test start. */
static DEFINE_MUTEX(boost_mutex); /* protect setting boost_starttime */
/* and boost task create/destroy. */
@@ -1713,12 +1723,14 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
}
// Give the scheduler a chance, even on nohz_full CPUs.
-static void rcu_torture_fwd_prog_cond_resched(void)
+static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
{
if (IS_ENABLED(CONFIG_PREEMPT) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
- if (need_resched())
+ // Real call_rcu() floods hit userspace, so emulate that.
+ if (need_resched() || (iter & 0xfff))
schedule();
} else {
+ // No userspace emulation: CB invocation throttles call_rcu()
cond_resched();
}
}
@@ -1746,7 +1758,7 @@ static unsigned long rcu_torture_fwd_prog_cbfree(void)
spin_unlock_irqrestore(&rcu_fwd_lock, flags);
kfree(rfcp);
freed++;
- rcu_torture_fwd_prog_cond_resched();
+ rcu_torture_fwd_prog_cond_resched(freed);
}
return freed;
}
@@ -1785,15 +1797,17 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
WRITE_ONCE(rcu_fwd_startat, jiffies);
stopat = rcu_fwd_startat + dur;
while (time_before(jiffies, stopat) &&
+ !shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
idx = cur_ops->readlock();
udelay(10);
cur_ops->readunlock(idx);
if (!fwd_progress_need_resched || need_resched())
- rcu_torture_fwd_prog_cond_resched();
+ rcu_torture_fwd_prog_cond_resched(1);
}
(*tested_tries)++;
if (!time_before(jiffies, stopat) &&
+ !shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
(*tested)++;
cver = READ_ONCE(rcu_torture_current_version) - cver;
@@ -1852,6 +1866,7 @@ static void rcu_torture_fwd_prog_cr(void)
gps = cur_ops->get_gp_seq();
rcu_launder_gp_seq_start = gps;
while (time_before(jiffies, stopat) &&
+ !shutdown_time_arrived() &&
!READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
rfcp = READ_ONCE(rcu_fwd_cb_head);
rfcpn = NULL;
@@ -1875,7 +1890,7 @@ static void rcu_torture_fwd_prog_cr(void)
rfcp->rfc_gps = 0;
}
cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
- rcu_torture_fwd_prog_cond_resched();
+ rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
}
stoppedat = jiffies;
n_launders_cb_snap = READ_ONCE(n_launders_cb);
@@ -1884,7 +1899,8 @@ static void rcu_torture_fwd_prog_cr(void)
cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
(void)rcu_torture_fwd_prog_cbfree();
- if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop)) {
+ if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
+ !shutdown_time_arrived()) {
WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
__func__,
@@ -2465,6 +2481,7 @@ rcu_torture_init(void)
goto unwind;
rcutor_hp = firsterr;
}
+ shutdown_jiffies = jiffies + shutdown_secs * HZ;
firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
if (firsterr)
goto unwind;
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 307ae6ebb804..99e9d952827b 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -313,15 +313,6 @@ void rcu_note_context_switch(bool preempt)
? rnp->gp_seq
: rcu_seq_snap(&rnp->gp_seq));
rcu_preempt_ctxt_queue(rnp, rdp);
- } else if (t->rcu_read_lock_nesting < 0 &&
- t->rcu_read_unlock_special.s) {
-
- /*
- * Complete exit from RCU read-side critical section on
- * behalf of preempted instance of __rcu_read_unlock().
- */
- rcu_read_unlock_special(t);
- rcu_preempt_deferred_qs(t);
} else {
rcu_preempt_deferred_qs(t);
}
@@ -624,22 +615,18 @@ static void rcu_read_unlock_special(struct task_struct *t)
(rdp->grpmask & rnp->expmask) ||
tick_nohz_full_cpu(rdp->cpu);
// Need to defer quiescent state until everything is enabled.
- if ((exp || in_irq()) && irqs_were_disabled && use_softirq &&
- (in_irq() || !t->rcu_read_unlock_special.b.deferred_qs)) {
+ if (irqs_were_disabled && use_softirq &&
+ (in_interrupt() ||
+ (exp && !t->rcu_read_unlock_special.b.deferred_qs))) {
// Using softirq, safe to awaken, and we get
// no help from enabling irqs, unlike bh/preempt.
raise_softirq_irqoff(RCU_SOFTIRQ);
- } else if (exp && irqs_were_disabled && !use_softirq &&
- !t->rcu_read_unlock_special.b.deferred_qs) {
- // Safe to awaken and we get no help from enabling
- // irqs, unlike bh/preempt.
- invoke_rcu_core();
} else {
// Enabling BH or preempt does reschedule, so...
// Also if no expediting or NO_HZ_FULL, slow is OK.
set_tsk_need_resched(current);
set_preempt_need_resched();
- if (IS_ENABLED(CONFIG_IRQ_WORK) &&
+ if (IS_ENABLED(CONFIG_IRQ_WORK) && irqs_were_disabled &&
!rdp->defer_qs_iw_pending && exp) {
// Get scheduler to re-evaluate and call hooks.
// If !IRQ_WORK, FQS scan will eventually IPI.
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 64e9cc8609e7..1861103662db 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -61,9 +61,15 @@ module_param(rcu_normal_after_boot, int, 0);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
/**
- * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section?
+ * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section?
+ * @ret: Best guess answer if lockdep cannot be relied on
*
- * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an
+ * Returns true if lockdep must be ignored, in which case *ret contains
+ * the best guess described below. Otherwise returns false, in which
+ * case *ret tells the caller nothing and the caller should instead
+ * consult lockdep.
+ *
+ * If CONFIG_DEBUG_LOCK_ALLOC is selected, set *ret to nonzero iff in an
* RCU-sched read-side critical section. In absence of
* CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side
* critical section unless it can prove otherwise. Note that disabling
@@ -75,35 +81,45 @@ module_param(rcu_normal_after_boot, int, 0);
* Check debug_lockdep_rcu_enabled() to prevent false positives during boot
* and while lockdep is disabled.
*
- * Note that if the CPU is in the idle loop from an RCU point of
- * view (ie: that we are in the section between rcu_idle_enter() and
- * rcu_idle_exit()) then rcu_read_lock_held() returns false even if the CPU
- * did an rcu_read_lock(). The reason for this is that RCU ignores CPUs
- * that are in such a section, considering these as in extended quiescent
- * state, so such a CPU is effectively never in an RCU read-side critical
- * section regardless of what RCU primitives it invokes. This state of
- * affairs is required --- we need to keep an RCU-free window in idle
- * where the CPU may possibly enter into low power mode. This way we can
- * notice an extended quiescent state to other CPUs that started a grace
- * period. Otherwise we would delay any grace period as long as we run in
- * the idle task.
+ * Note that if the CPU is in the idle loop from an RCU point of view (ie:
+ * that we are in the section between rcu_idle_enter() and rcu_idle_exit())
+ * then rcu_read_lock_held() sets *ret to false even if the CPU did an
+ * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are
+ * in such a section, considering these as in extended quiescent state,
+ * so such a CPU is effectively never in an RCU read-side critical section
+ * regardless of what RCU primitives it invokes. This state of affairs is
+ * required --- we need to keep an RCU-free window in idle where the CPU may
+ * possibly enter into low power mode. This way we can notice an extended
+ * quiescent state to other CPUs that started a grace period. Otherwise
+ * we would delay any grace period as long as we run in the idle task.
*
- * Similarly, we avoid claiming an SRCU read lock held if the current
+ * Similarly, we avoid claiming an RCU read lock held if the current
* CPU is offline.
*/
+static bool rcu_read_lock_held_common(bool *ret)
+{
+ if (!debug_lockdep_rcu_enabled()) {
+ *ret = 1;
+ return true;
+ }
+ if (!rcu_is_watching()) {
+ *ret = 0;
+ return true;
+ }
+ if (!rcu_lockdep_current_cpu_online()) {
+ *ret = 0;
+ return true;
+ }
+ return false;
+}
+
int rcu_read_lock_sched_held(void)
{
- int lockdep_opinion = 0;
+ bool ret;
- if (!debug_lockdep_rcu_enabled())
- return 1;
- if (!rcu_is_watching())
- return 0;
- if (!rcu_lockdep_current_cpu_online())
- return 0;
- if (debug_locks)
- lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
- return lockdep_opinion || !preemptible();
+ if (rcu_read_lock_held_common(&ret))
+ return ret;
+ return lock_is_held(&rcu_sched_lock_map) || !preemptible();
}
EXPORT_SYMBOL(rcu_read_lock_sched_held);
#endif
@@ -260,12 +276,10 @@ NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled);
*/
int rcu_read_lock_held(void)
{
- if (!debug_lockdep_rcu_enabled())
- return 1;
- if (!rcu_is_watching())
- return 0;
- if (!rcu_lockdep_current_cpu_online())
- return 0;
+ bool ret;
+
+ if (rcu_read_lock_held_common(&ret))
+ return ret;
return lock_is_held(&rcu_lock_map);
}
EXPORT_SYMBOL_GPL(rcu_read_lock_held);
@@ -287,16 +301,28 @@ EXPORT_SYMBOL_GPL(rcu_read_lock_held);
*/
int rcu_read_lock_bh_held(void)
{
- if (!debug_lockdep_rcu_enabled())
- return 1;
- if (!rcu_is_watching())
- return 0;
- if (!rcu_lockdep_current_cpu_online())
- return 0;
+ bool ret;
+
+ if (rcu_read_lock_held_common(&ret))
+ return ret;
return in_softirq() || irqs_disabled();
}
EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
+int rcu_read_lock_any_held(void)
+{
+ bool ret;
+
+ if (rcu_read_lock_held_common(&ret))
+ return ret;
+ if (lock_is_held(&rcu_lock_map) ||
+ lock_is_held(&rcu_bh_lock_map) ||
+ lock_is_held(&rcu_sched_lock_map))
+ return 1;
+ return !preemptible();
+}
+EXPORT_SYMBOL_GPL(rcu_read_lock_any_held);
+
#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
/**
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-07 20:42:52 +0000