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Threads

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A thread is a struct proc that shares three counted objects with others of
its group: the address space (struct mm: page tables, heap top, VMAs and a
lock for changing them), the descriptor table, and the signal dispositions.
clone() shares what its flags say and fork() copies.

- clone(): pthread_create's shape (VM, FILES, SIGHAND, THREAD, SETTLS,
  PARENT_SETTID, CHILD_CLEARTID) and posix_spawn's (VM, VFORK, a stack).
- futex: WAIT, WAIT_BITSET with timeouts, WAKE, REQUEUE, CMP_REQUEUE, keyed
  by the word's kernel address so shared pages meet. set_tid_address keeps
  the word that exit zeroes and wakes, for pthread_join.
- exit ends a thread; exit_group, a fatal signal, or the leader exiting ends
  them all. reapd frees exited threads; the leader is reaped by its parent
  once the rest are gone. getpid is the group, gettid the thread.
- Stops and resumes reach every thread; other process signals the leader.
- exec kills the other threads and unshares the dispositions.
- No TLB shootdown, so pages unmapped from a shared address space are freed
  only once every CPU has reloaded CR3 or is idle.
- procfs: /proc lists processes, task/ lists threads, comm, Threads:, Tgid.
- The console honours VMIN 0 / VTIME (btop's input drain hung on it).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
This commit is contained in:
Nexoniarz 2026-10-25 03:03:50 +01:00
commit f4d7f9100d
19 changed files with 1300 additions and 248 deletions
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10
kernel/dev/pciuser.c
View file

@ -664,7 +664,7 @@ do_dma(uint64 argp)
struct vma *v = 0;
for (int i = 0; i < NVMA; i++)
if (!p->vma[i].used) { v = &p->vma[i]; break; }
if (!p->mm->vma[i].used) { v = &p->mm->vma[i]; break; }
if (!v) {
blk->proc = 0;
return -ENOMEM;
@ -672,9 +672,9 @@ do_dma(uint64 argp)
// Its own mapping in the caller, taken from the same bump allocator mmap
// uses so the two cannot collide.
if (p->mmap_next == 0)
p->mmap_next = 0x40000000;
uint64 va = p->mmap_next;
if (p->mm->mmap_next == 0)
p->mm->mmap_next = 0x40000000;
uint64 va = p->mm->mmap_next;
if (va + size < va || va + size > KERNBASE) {
blk->proc = 0;
return -ENOMEM;
@ -685,7 +685,7 @@ do_dma(uint64 argp)
blk->proc = 0;
return -ENOMEM;
}
p->mmap_next += size;
p->mm->mmap_next += size;
uint64 phys = dma_phys(kva);
if (mappages(p->pgdir, (void *)va, size, phys, PTE_W | PTE_U) < 0) {