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Expands the kernel-and-TTY core with the primitives the higher layers have
been missing, plus an in-kernel harness that proves they work.
Data structures (lib/):
- rbtree.c: Linux-compatible red-black tree with parent pointers, full
insert/erase rebalancing, in-order iteration and an invariant validator.
- kfifo.c: power-of-two byte ring with free-running indices, so the wrap
path costs one mask instead of a branch per byte.
- hashtable.c: separately-chained table with FNV-1a hashing, string or
u64 keys, and rehash-on-growth at a 3/4 load factor.
Kernel subsystems:
- kernel/wait.c: wait queues and one-shot completion barriers, backed by a
static sleeper pool so a blocking path never re-enters the allocator.
- kernel/futex.c: 32-bucket futex hash with value re-check, requeue, and an
fmutex_t sleeping mutex built on the uncontended-fastpath protocol.
- kernel/rcu.c: tiny RCU with reader nesting, deferred callbacks, kfree_rcu
and rcu_assign_pointer/rcu_dereference publish barriers.
- mm/page_cache.c: write-back block page cache, 4 KB pages indexed by
(device, page), CLOCK second-chance eviction and dirty write-back.
- kernel/ktest.c: KUnit-style harness with 6 built-in suites, 21 cases and
735 assertions covering every subsystem above (all passing under QEMU).
LazyBox userland:
- coreutils.c: sort, uniq, cut, tr, rev, tac, nl, seq, diff, xxd, du,
factor, sum and truncate, reading through the VFS and handling the
zero-length synthetic nodes that procfs and sysfs expose.
- ktest, rcuinfo, futexinfo, waitinfo and pagecache diagnostics applets.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01L5yKJT4Wo2cV3rfPrwY5MP
66 lines
2.0 KiB
C
66 lines
2.0 KiB
C
#ifndef _KERNEL_WAIT_H
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#define _KERNEL_WAIT_H
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#include <stdint.h>
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#include <stddef.h>
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#include <stdbool.h>
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#include <lib/list.h>
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#include <kernel/sync.h>
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#include <kernel/task.h>
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// Wait queues and completions.
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//
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// SUB-OS runs a cooperative round-robin scheduler, so a sleeper parks itself
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// on the queue, marks its task BLOCKED and yields until a waker flips the
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// entry's `woken` flag. Timed waits fall back to the PIT tick counter.
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typedef struct wait_entry {
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task_t* task;
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volatile bool woken;
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struct list_head node;
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} wait_entry_t;
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typedef struct wait_queue {
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char name[24];
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struct list_head waiters;
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spinlock_t lock;
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uint64_t wakeups;
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uint64_t sleeps;
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uint32_t nr_waiting;
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} wait_queue_t;
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void wait_queue_init(wait_queue_t* wq, const char* name);
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// Park the caller until woken. Returns 0 on wake, -1 if the queue is full.
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int wait_event(wait_queue_t* wq);
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// Park the caller for at most `timeout_ticks` PIT ticks (100 Hz).
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// Returns 0 if woken, 1 if the wait timed out.
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int wait_event_timeout(wait_queue_t* wq, uint64_t timeout_ticks);
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// Wake the longest-waiting sleeper, or every sleeper. Returns the count woken.
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int wake_up(wait_queue_t* wq);
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int wake_up_all(wait_queue_t* wq);
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uint32_t wait_queue_waiters(const wait_queue_t* wq);
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// ---------------------------------------------------------------------------
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// Completions: one-shot "this is done" barriers built on a wait queue.
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// ---------------------------------------------------------------------------
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typedef struct completion {
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wait_queue_t wq;
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volatile bool done;
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} completion_t;
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void completion_init(completion_t* c, const char* name);
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void wait_for_completion(completion_t* c);
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int wait_for_completion_timeout(completion_t* c, uint64_t timeout_ticks);
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void complete(completion_t* c);
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void complete_all(completion_t* c);
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bool completion_done(const completion_t* c);
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void wait_subsystem_init(void);
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void wait_dump_stats(void);
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#endif // _KERNEL_WAIT_H
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