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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /kernel/rcu/tiny.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'kernel/rcu/tiny.c')
-rw-r--r--kernel/rcu/tiny.c263
1 files changed, 263 insertions, 0 deletions
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
new file mode 100644
index 0000000000..42f7589e51
--- /dev/null
+++ b/kernel/rcu/tiny.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
+ *
+ * Copyright IBM Corporation, 2008
+ *
+ * Author: Paul E. McKenney <paulmck@linux.ibm.com>
+ *
+ * For detailed explanation of Read-Copy Update mechanism see -
+ * Documentation/RCU
+ */
+#include <linux/completion.h>
+#include <linux/interrupt.h>
+#include <linux/notifier.h>
+#include <linux/rcupdate_wait.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/time.h>
+#include <linux/cpu.h>
+#include <linux/prefetch.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+
+#include "rcu.h"
+
+/* Global control variables for rcupdate callback mechanism. */
+struct rcu_ctrlblk {
+ struct rcu_head *rcucblist; /* List of pending callbacks (CBs). */
+ struct rcu_head **donetail; /* ->next pointer of last "done" CB. */
+ struct rcu_head **curtail; /* ->next pointer of last CB. */
+ unsigned long gp_seq; /* Grace-period counter. */
+};
+
+/* Definition for rcupdate control block. */
+static struct rcu_ctrlblk rcu_ctrlblk = {
+ .donetail = &rcu_ctrlblk.rcucblist,
+ .curtail = &rcu_ctrlblk.rcucblist,
+ .gp_seq = 0 - 300UL,
+};
+
+void rcu_barrier(void)
+{
+ wait_rcu_gp(call_rcu_hurry);
+}
+EXPORT_SYMBOL(rcu_barrier);
+
+/* Record an rcu quiescent state. */
+void rcu_qs(void)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail) {
+ rcu_ctrlblk.donetail = rcu_ctrlblk.curtail;
+ raise_softirq_irqoff(RCU_SOFTIRQ);
+ }
+ WRITE_ONCE(rcu_ctrlblk.gp_seq, rcu_ctrlblk.gp_seq + 2);
+ local_irq_restore(flags);
+}
+
+/*
+ * Check to see if the scheduling-clock interrupt came from an extended
+ * quiescent state, and, if so, tell RCU about it. This function must
+ * be called from hardirq context. It is normally called from the
+ * scheduling-clock interrupt.
+ */
+void rcu_sched_clock_irq(int user)
+{
+ if (user) {
+ rcu_qs();
+ } else if (rcu_ctrlblk.donetail != rcu_ctrlblk.curtail) {
+ set_tsk_need_resched(current);
+ set_preempt_need_resched();
+ }
+}
+
+/*
+ * Reclaim the specified callback, either by invoking it for non-kfree cases or
+ * freeing it directly (for kfree). Return true if kfreeing, false otherwise.
+ */
+static inline bool rcu_reclaim_tiny(struct rcu_head *head)
+{
+ rcu_callback_t f;
+ unsigned long offset = (unsigned long)head->func;
+
+ rcu_lock_acquire(&rcu_callback_map);
+ if (__is_kvfree_rcu_offset(offset)) {
+ trace_rcu_invoke_kvfree_callback("", head, offset);
+ kvfree((void *)head - offset);
+ rcu_lock_release(&rcu_callback_map);
+ return true;
+ }
+
+ trace_rcu_invoke_callback("", head);
+ f = head->func;
+ WRITE_ONCE(head->func, (rcu_callback_t)0L);
+ f(head);
+ rcu_lock_release(&rcu_callback_map);
+ return false;
+}
+
+/* Invoke the RCU callbacks whose grace period has elapsed. */
+static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
+{
+ struct rcu_head *next, *list;
+ unsigned long flags;
+
+ /* Move the ready-to-invoke callbacks to a local list. */
+ local_irq_save(flags);
+ if (rcu_ctrlblk.donetail == &rcu_ctrlblk.rcucblist) {
+ /* No callbacks ready, so just leave. */
+ local_irq_restore(flags);
+ return;
+ }
+ list = rcu_ctrlblk.rcucblist;
+ rcu_ctrlblk.rcucblist = *rcu_ctrlblk.donetail;
+ *rcu_ctrlblk.donetail = NULL;
+ if (rcu_ctrlblk.curtail == rcu_ctrlblk.donetail)
+ rcu_ctrlblk.curtail = &rcu_ctrlblk.rcucblist;
+ rcu_ctrlblk.donetail = &rcu_ctrlblk.rcucblist;
+ local_irq_restore(flags);
+
+ /* Invoke the callbacks on the local list. */
+ while (list) {
+ next = list->next;
+ prefetch(next);
+ debug_rcu_head_unqueue(list);
+ local_bh_disable();
+ rcu_reclaim_tiny(list);
+ local_bh_enable();
+ list = next;
+ }
+}
+
+/*
+ * Wait for a grace period to elapse. But it is illegal to invoke
+ * synchronize_rcu() from within an RCU read-side critical section.
+ * Therefore, any legal call to synchronize_rcu() is a quiescent state,
+ * and so on a UP system, synchronize_rcu() need do nothing, other than
+ * let the polled APIs know that another grace period elapsed.
+ *
+ * (But Lai Jiangshan points out the benefits of doing might_sleep()
+ * to reduce latency.)
+ *
+ * Cool, huh? (Due to Josh Triplett.)
+ */
+void synchronize_rcu(void)
+{
+ RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) ||
+ lock_is_held(&rcu_lock_map) ||
+ lock_is_held(&rcu_sched_lock_map),
+ "Illegal synchronize_rcu() in RCU read-side critical section");
+ WRITE_ONCE(rcu_ctrlblk.gp_seq, rcu_ctrlblk.gp_seq + 2);
+}
+EXPORT_SYMBOL_GPL(synchronize_rcu);
+
+static void tiny_rcu_leak_callback(struct rcu_head *rhp)
+{
+}
+
+/*
+ * Post an RCU callback to be invoked after the end of an RCU grace
+ * period. But since we have but one CPU, that would be after any
+ * quiescent state.
+ */
+void call_rcu(struct rcu_head *head, rcu_callback_t func)
+{
+ static atomic_t doublefrees;
+ unsigned long flags;
+
+ if (debug_rcu_head_queue(head)) {
+ if (atomic_inc_return(&doublefrees) < 4) {
+ pr_err("%s(): Double-freed CB %p->%pS()!!! ", __func__, head, head->func);
+ mem_dump_obj(head);
+ }
+
+ if (!__is_kvfree_rcu_offset((unsigned long)head->func))
+ WRITE_ONCE(head->func, tiny_rcu_leak_callback);
+ return;
+ }
+
+ head->func = func;
+ head->next = NULL;
+
+ local_irq_save(flags);
+ *rcu_ctrlblk.curtail = head;
+ rcu_ctrlblk.curtail = &head->next;
+ local_irq_restore(flags);
+
+ if (unlikely(is_idle_task(current))) {
+ /* force scheduling for rcu_qs() */
+ resched_cpu(0);
+ }
+}
+EXPORT_SYMBOL_GPL(call_rcu);
+
+/*
+ * Store a grace-period-counter "cookie". For more information,
+ * see the Tree RCU header comment.
+ */
+void get_completed_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
+{
+ rgosp->rgos_norm = RCU_GET_STATE_COMPLETED;
+}
+EXPORT_SYMBOL_GPL(get_completed_synchronize_rcu_full);
+
+/*
+ * Return a grace-period-counter "cookie". For more information,
+ * see the Tree RCU header comment.
+ */
+unsigned long get_state_synchronize_rcu(void)
+{
+ return READ_ONCE(rcu_ctrlblk.gp_seq);
+}
+EXPORT_SYMBOL_GPL(get_state_synchronize_rcu);
+
+/*
+ * Return a grace-period-counter "cookie" and ensure that a future grace
+ * period completes. For more information, see the Tree RCU header comment.
+ */
+unsigned long start_poll_synchronize_rcu(void)
+{
+ unsigned long gp_seq = get_state_synchronize_rcu();
+
+ if (unlikely(is_idle_task(current))) {
+ /* force scheduling for rcu_qs() */
+ resched_cpu(0);
+ }
+ return gp_seq;
+}
+EXPORT_SYMBOL_GPL(start_poll_synchronize_rcu);
+
+/*
+ * Return true if the grace period corresponding to oldstate has completed
+ * and false otherwise. For more information, see the Tree RCU header
+ * comment.
+ */
+bool poll_state_synchronize_rcu(unsigned long oldstate)
+{
+ return oldstate == RCU_GET_STATE_COMPLETED || READ_ONCE(rcu_ctrlblk.gp_seq) != oldstate;
+}
+EXPORT_SYMBOL_GPL(poll_state_synchronize_rcu);
+
+#ifdef CONFIG_KASAN_GENERIC
+void kvfree_call_rcu(struct rcu_head *head, void *ptr)
+{
+ if (head)
+ kasan_record_aux_stack_noalloc(ptr);
+
+ __kvfree_call_rcu(head, ptr);
+}
+EXPORT_SYMBOL_GPL(kvfree_call_rcu);
+#endif
+
+void __init rcu_init(void)
+{
+ open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+ rcu_early_boot_tests();
+}