Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 600 insertions, 0 deletions

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
new file mode 100644
index 000000000..849f0aa99
--- /dev/null
+++ b/kernel/rcu/update.c
@@ -0,0 +1,600 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Read-Copy Update mechanism for mutual exclusion
+ *
+ * Copyright IBM Corporation, 2001
+ *
+ * Authors: Dipankar Sarma <dipankar@in.ibm.com>
+ *	    Manfred Spraul <manfred@colorfullife.com>
+ *
+ * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
+ * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
+ * Papers:
+ * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
+ * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
+ *
+ * For detailed explanation of Read-Copy Update mechanism see -
+ *		http://lse.sourceforge.net/locking/rcupdate.html
+ *
+ */
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/debug.h>
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/percpu.h>
+#include <linux/notifier.h>
+#include <linux/cpu.h>
+#include <linux/mutex.h>
+#include <linux/export.h>
+#include <linux/hardirq.h>
+#include <linux/delay.h>
+#include <linux/moduleparam.h>
+#include <linux/kthread.h>
+#include <linux/tick.h>
+#include <linux/rcupdate_wait.h>
+#include <linux/sched/isolation.h>
+#include <linux/kprobes.h>
+#include <linux/slab.h>
+#include <linux/irq_work.h>
+#include <linux/rcupdate_trace.h>
+
+#define CREATE_TRACE_POINTS
+
+#include "rcu.h"
+
+#ifdef MODULE_PARAM_PREFIX
+#undef MODULE_PARAM_PREFIX
+#endif
+#define MODULE_PARAM_PREFIX "rcupdate."
+
+#ifndef CONFIG_TINY_RCU
+module_param(rcu_expedited, int, 0);
+module_param(rcu_normal, int, 0);
+static int rcu_normal_after_boot;
+module_param(rcu_normal_after_boot, int, 0);
+#endif /* #ifndef CONFIG_TINY_RCU */
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+/**
+ * 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
+ *
+ * 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
+ * of preemption (including disabling irqs) counts as an RCU-sched
+ * read-side critical section.  This is useful for debug checks in functions
+ * that required that they be called within an RCU-sched read-side
+ * critical section.
+ *
+ * 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() 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 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 = true;
+		return true;
+	}
+	if (!rcu_is_watching()) {
+		*ret = false;
+		return true;
+	}
+	if (!rcu_lockdep_current_cpu_online()) {
+		*ret = false;
+		return true;
+	}
+	return false;
+}
+
+int rcu_read_lock_sched_held(void)
+{
+	bool ret;
+
+	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
+
+#ifndef CONFIG_TINY_RCU
+
+/*
+ * Should expedited grace-period primitives always fall back to their
+ * non-expedited counterparts?  Intended for use within RCU.  Note
+ * that if the user specifies both rcu_expedited and rcu_normal, then
+ * rcu_normal wins.  (Except during the time period during boot from
+ * when the first task is spawned until the rcu_set_runtime_mode()
+ * core_initcall() is invoked, at which point everything is expedited.)
+ */
+bool rcu_gp_is_normal(void)
+{
+	return READ_ONCE(rcu_normal) &&
+	       rcu_scheduler_active != RCU_SCHEDULER_INIT;
+}
+EXPORT_SYMBOL_GPL(rcu_gp_is_normal);
+
+static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1);
+
+/*
+ * Should normal grace-period primitives be expedited?  Intended for
+ * use within RCU.  Note that this function takes the rcu_expedited
+ * sysfs/boot variable and rcu_scheduler_active into account as well
+ * as the rcu_expedite_gp() nesting.  So looping on rcu_unexpedite_gp()
+ * until rcu_gp_is_expedited() returns false is a -really- bad idea.
+ */
+bool rcu_gp_is_expedited(void)
+{
+	return rcu_expedited || atomic_read(&rcu_expedited_nesting);
+}
+EXPORT_SYMBOL_GPL(rcu_gp_is_expedited);
+
+/**
+ * rcu_expedite_gp - Expedite future RCU grace periods
+ *
+ * After a call to this function, future calls to synchronize_rcu() and
+ * friends act as the corresponding synchronize_rcu_expedited() function
+ * had instead been called.
+ */
+void rcu_expedite_gp(void)
+{
+	atomic_inc(&rcu_expedited_nesting);
+}
+EXPORT_SYMBOL_GPL(rcu_expedite_gp);
+
+/**
+ * rcu_unexpedite_gp - Cancel prior rcu_expedite_gp() invocation
+ *
+ * Undo a prior call to rcu_expedite_gp().  If all prior calls to
+ * rcu_expedite_gp() are undone by a subsequent call to rcu_unexpedite_gp(),
+ * and if the rcu_expedited sysfs/boot parameter is not set, then all
+ * subsequent calls to synchronize_rcu() and friends will return to
+ * their normal non-expedited behavior.
+ */
+void rcu_unexpedite_gp(void)
+{
+	atomic_dec(&rcu_expedited_nesting);
+}
+EXPORT_SYMBOL_GPL(rcu_unexpedite_gp);
+
+static bool rcu_boot_ended __read_mostly;
+
+/*
+ * Inform RCU of the end of the in-kernel boot sequence.
+ */
+void rcu_end_inkernel_boot(void)
+{
+	rcu_unexpedite_gp();
+	if (rcu_normal_after_boot)
+		WRITE_ONCE(rcu_normal, 1);
+	rcu_boot_ended = true;
+}
+
+/*
+ * Let rcutorture know when it is OK to turn it up to eleven.
+ */
+bool rcu_inkernel_boot_has_ended(void)
+{
+	return rcu_boot_ended;
+}
+EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended);
+
+#endif /* #ifndef CONFIG_TINY_RCU */
+
+/*
+ * Test each non-SRCU synchronous grace-period wait API.  This is
+ * useful just after a change in mode for these primitives, and
+ * during early boot.
+ */
+void rcu_test_sync_prims(void)
+{
+	if (!IS_ENABLED(CONFIG_PROVE_RCU))
+		return;
+	synchronize_rcu();
+	synchronize_rcu_expedited();
+}
+
+#if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU)
+
+/*
+ * Switch to run-time mode once RCU has fully initialized.
+ */
+static int __init rcu_set_runtime_mode(void)
+{
+	rcu_test_sync_prims();
+	rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
+	kfree_rcu_scheduler_running();
+	rcu_test_sync_prims();
+	return 0;
+}
+core_initcall(rcu_set_runtime_mode);
+
+#endif /* #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) */
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static struct lock_class_key rcu_lock_key;
+struct lockdep_map rcu_lock_map = {
+	.name = "rcu_read_lock",
+	.key = &rcu_lock_key,
+	.wait_type_outer = LD_WAIT_FREE,
+	.wait_type_inner = LD_WAIT_CONFIG, /* XXX PREEMPT_RCU ? */
+};
+EXPORT_SYMBOL_GPL(rcu_lock_map);
+
+static struct lock_class_key rcu_bh_lock_key;
+struct lockdep_map rcu_bh_lock_map = {
+	.name = "rcu_read_lock_bh",
+	.key = &rcu_bh_lock_key,
+	.wait_type_outer = LD_WAIT_FREE,
+	.wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_LOCK also makes BH preemptible */
+};
+EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
+
+static struct lock_class_key rcu_sched_lock_key;
+struct lockdep_map rcu_sched_lock_map = {
+	.name = "rcu_read_lock_sched",
+	.key = &rcu_sched_lock_key,
+	.wait_type_outer = LD_WAIT_FREE,
+	.wait_type_inner = LD_WAIT_SPIN,
+};
+EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
+
+// Tell lockdep when RCU callbacks are being invoked.
+static struct lock_class_key rcu_callback_key;
+struct lockdep_map rcu_callback_map =
+	STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key);
+EXPORT_SYMBOL_GPL(rcu_callback_map);
+
+noinstr int notrace debug_lockdep_rcu_enabled(void)
+{
+	return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && READ_ONCE(debug_locks) &&
+	       current->lockdep_recursion == 0;
+}
+EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
+
+/**
+ * rcu_read_lock_held() - might we be in RCU read-side critical section?
+ *
+ * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU
+ * read-side critical section.  In absence of CONFIG_DEBUG_LOCK_ALLOC,
+ * this assumes we are in an RCU read-side critical section unless it can
+ * prove otherwise.  This is useful for debug checks in functions that
+ * require that they be called within an RCU read-side critical section.
+ *
+ * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
+ * and while lockdep is disabled.
+ *
+ * Note that rcu_read_lock() and the matching rcu_read_unlock() must
+ * occur in the same context, for example, it is illegal to invoke
+ * rcu_read_unlock() in process context if the matching rcu_read_lock()
+ * was invoked from within an irq handler.
+ *
+ * Note that rcu_read_lock() is disallowed if the CPU is either idle or
+ * offline from an RCU perspective, so check for those as well.
+ */
+int rcu_read_lock_held(void)
+{
+	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);
+
+/**
+ * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section?
+ *
+ * Check for bottom half being disabled, which covers both the
+ * CONFIG_PROVE_RCU and not cases.  Note that if someone uses
+ * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled)
+ * will show the situation.  This is useful for debug checks in functions
+ * that require that they be called within an RCU read-side critical
+ * section.
+ *
+ * Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
+ *
+ * Note that rcu_read_lock_bh() is disallowed if the CPU is either idle or
+ * offline from an RCU perspective, so check for those as well.
+ */
+int rcu_read_lock_bh_held(void)
+{
+	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 */
+
+/**
+ * wakeme_after_rcu() - Callback function to awaken a task after grace period
+ * @head: Pointer to rcu_head member within rcu_synchronize structure
+ *
+ * Awaken the corresponding task now that a grace period has elapsed.
+ */
+void wakeme_after_rcu(struct rcu_head *head)
+{
+	struct rcu_synchronize *rcu;
+
+	rcu = container_of(head, struct rcu_synchronize, head);
+	complete(&rcu->completion);
+}
+EXPORT_SYMBOL_GPL(wakeme_after_rcu);
+
+void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
+		   struct rcu_synchronize *rs_array)
+{
+	int i;
+	int j;
+
+	/* Initialize and register callbacks for each crcu_array element. */
+	for (i = 0; i < n; i++) {
+		if (checktiny &&
+		    (crcu_array[i] == call_rcu)) {
+			might_sleep();
+			continue;
+		}
+		for (j = 0; j < i; j++)
+			if (crcu_array[j] == crcu_array[i])
+				break;
+		if (j == i) {
+			init_rcu_head_on_stack(&rs_array[i].head);
+			init_completion(&rs_array[i].completion);
+			(crcu_array[i])(&rs_array[i].head, wakeme_after_rcu);
+		}
+	}
+
+	/* Wait for all callbacks to be invoked. */
+	for (i = 0; i < n; i++) {
+		if (checktiny &&
+		    (crcu_array[i] == call_rcu))
+			continue;
+		for (j = 0; j < i; j++)
+			if (crcu_array[j] == crcu_array[i])
+				break;
+		if (j == i) {
+			wait_for_completion(&rs_array[i].completion);
+			destroy_rcu_head_on_stack(&rs_array[i].head);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(__wait_rcu_gp);
+
+#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
+void init_rcu_head(struct rcu_head *head)
+{
+	debug_object_init(head, &rcuhead_debug_descr);
+}
+EXPORT_SYMBOL_GPL(init_rcu_head);
+
+void destroy_rcu_head(struct rcu_head *head)
+{
+	debug_object_free(head, &rcuhead_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_rcu_head);
+
+static bool rcuhead_is_static_object(void *addr)
+{
+	return true;
+}
+
+/**
+ * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects
+ * @head: pointer to rcu_head structure to be initialized
+ *
+ * This function informs debugobjects of a new rcu_head structure that
+ * has been allocated as an auto variable on the stack.  This function
+ * is not required for rcu_head structures that are statically defined or
+ * that are dynamically allocated on the heap.  This function has no
+ * effect for !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds.
+ */
+void init_rcu_head_on_stack(struct rcu_head *head)
+{
+	debug_object_init_on_stack(head, &rcuhead_debug_descr);
+}
+EXPORT_SYMBOL_GPL(init_rcu_head_on_stack);
+
+/**
+ * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects
+ * @head: pointer to rcu_head structure to be initialized
+ *
+ * This function informs debugobjects that an on-stack rcu_head structure
+ * is about to go out of scope.  As with init_rcu_head_on_stack(), this
+ * function is not required for rcu_head structures that are statically
+ * defined or that are dynamically allocated on the heap.  Also as with
+ * init_rcu_head_on_stack(), this function has no effect for
+ * !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds.
+ */
+void destroy_rcu_head_on_stack(struct rcu_head *head)
+{
+	debug_object_free(head, &rcuhead_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack);
+
+const struct debug_obj_descr rcuhead_debug_descr = {
+	.name = "rcu_head",
+	.is_static_object = rcuhead_is_static_object,
+};
+EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
+#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+
+#if defined(CONFIG_TREE_RCU) || defined(CONFIG_RCU_TRACE)
+void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp,
+			       unsigned long secs,
+			       unsigned long c_old, unsigned long c)
+{
+	trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c);
+}
+EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
+#else
+#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
+	do { } while (0)
+#endif
+
+#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST)
+/* Get rcutorture access to sched_setaffinity(). */
+long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
+{
+	int ret;
+
+	ret = sched_setaffinity(pid, in_mask);
+	WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity);
+#endif
+
+#ifdef CONFIG_RCU_STALL_COMMON
+int rcu_cpu_stall_ftrace_dump __read_mostly;
+module_param(rcu_cpu_stall_ftrace_dump, int, 0644);
+int rcu_cpu_stall_suppress __read_mostly; // !0 = suppress stall warnings.
+EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);
+module_param(rcu_cpu_stall_suppress, int, 0644);
+int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
+module_param(rcu_cpu_stall_timeout, int, 0644);
+#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
+
+// Suppress boot-time RCU CPU stall warnings and rcutorture writer stall
+// warnings.  Also used by rcutorture even if stall warnings are excluded.
+int rcu_cpu_stall_suppress_at_boot __read_mostly; // !0 = suppress boot stalls.
+EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress_at_boot);
+module_param(rcu_cpu_stall_suppress_at_boot, int, 0444);
+
+#ifdef CONFIG_PROVE_RCU
+
+/*
+ * Early boot self test parameters.
+ */
+static bool rcu_self_test;
+module_param(rcu_self_test, bool, 0444);
+
+static int rcu_self_test_counter;
+
+static void test_callback(struct rcu_head *r)
+{
+	rcu_self_test_counter++;
+	pr_info("RCU test callback executed %d\n", rcu_self_test_counter);
+}
+
+DEFINE_STATIC_SRCU(early_srcu);
+
+struct early_boot_kfree_rcu {
+	struct rcu_head rh;
+};
+
+static void early_boot_test_call_rcu(void)
+{
+	static struct rcu_head head;
+	static struct rcu_head shead;
+	struct early_boot_kfree_rcu *rhp;
+
+	call_rcu(&head, test_callback);
+	if (IS_ENABLED(CONFIG_SRCU))
+		call_srcu(&early_srcu, &shead, test_callback);
+	rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
+	if (!WARN_ON_ONCE(!rhp))
+		kfree_rcu(rhp, rh);
+}
+
+void rcu_early_boot_tests(void)
+{
+	pr_info("Running RCU self tests\n");
+
+	if (rcu_self_test)
+		early_boot_test_call_rcu();
+	rcu_test_sync_prims();
+}
+
+static int rcu_verify_early_boot_tests(void)
+{
+	int ret = 0;
+	int early_boot_test_counter = 0;
+
+	if (rcu_self_test) {
+		early_boot_test_counter++;
+		rcu_barrier();
+		if (IS_ENABLED(CONFIG_SRCU)) {
+			early_boot_test_counter++;
+			srcu_barrier(&early_srcu);
+		}
+	}
+	if (rcu_self_test_counter != early_boot_test_counter) {
+		WARN_ON(1);
+		ret = -1;
+	}
+
+	return ret;
+}
+late_initcall(rcu_verify_early_boot_tests);
+#else
+void rcu_early_boot_tests(void) {}
+#endif /* CONFIG_PROVE_RCU */
+
+#include "tasks.h"
+
+#ifndef CONFIG_TINY_RCU
+
+/*
+ * Print any significant non-default boot-time settings.
+ */
+void __init rcupdate_announce_bootup_oddness(void)
+{
+	if (rcu_normal)
+		pr_info("\tNo expedited grace period (rcu_normal).\n");
+	else if (rcu_normal_after_boot)
+		pr_info("\tNo expedited grace period (rcu_normal_after_boot).\n");
+	else if (rcu_expedited)
+		pr_info("\tAll grace periods are expedited (rcu_expedited).\n");
+	if (rcu_cpu_stall_suppress)
+		pr_info("\tRCU CPU stall warnings suppressed (rcu_cpu_stall_suppress).\n");
+	if (rcu_cpu_stall_timeout != CONFIG_RCU_CPU_STALL_TIMEOUT)
+		pr_info("\tRCU CPU stall warnings timeout set to %d (rcu_cpu_stall_timeout).\n", rcu_cpu_stall_timeout);
+	rcu_tasks_bootup_oddness();
+}
+
+#endif /* #ifndef CONFIG_TINY_RCU */