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subhobhai943andClaude Opus 5
f9400f6ac4
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
59 lines
1.7 KiB
C
59 lines
1.7 KiB
C
#ifndef _KERNEL_RCU_H
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#define _KERNEL_RCU_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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// Tiny RCU (Read-Copy-Update).
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//
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// Readers are free: rcu_read_lock() only bumps a per-CPU nesting depth, so a
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// lookup never contends with an update. Writers publish a new version with
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// rcu_assign_pointer() and defer reclamation of the old one until every reader
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// that could still hold a reference has finished — a "grace period".
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#define RCU_MAX_CALLBACKS 64
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typedef void (*rcu_callback_t)(void* arg);
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typedef struct {
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uint64_t grace_periods;
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uint64_t callbacks_queued;
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uint64_t callbacks_invoked;
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uint64_t read_locks;
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uint32_t nesting_depth;
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uint32_t pending;
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} rcu_stats_t;
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void rcu_init(void);
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void rcu_read_lock(void);
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void rcu_read_unlock(void);
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bool rcu_read_lock_held(void);
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// Block until every reader active at call time has left its critical section.
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void rcu_synchronize(void);
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// Queue `func(arg)` to run once the current grace period elapses.
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int call_rcu(rcu_callback_t func, void* arg);
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// Free `ptr` after a grace period (the common case for call_rcu).
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int kfree_rcu(void* ptr);
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// Advance the state machine; called from the timer tick and from rcu_synchronize.
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void rcu_process_callbacks(void);
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uint64_t rcu_get_grace_period(void);
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rcu_stats_t rcu_get_stats(void);
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void rcu_dump(void);
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// Publish/consume helpers. The barriers keep the compiler from reordering the
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// initialisation of an object past the store that makes it visible.
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#define rcu_assign_pointer(p, v) \
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do { __atomic_store_n(&(p), (v), __ATOMIC_RELEASE); } while (0)
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#define rcu_dereference(p) \
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__atomic_load_n(&(p), __ATOMIC_ACQUIRE)
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#endif // _KERNEL_RCU_H
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