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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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8
kernel/sys/sys_poll.c
View file

@ -79,12 +79,12 @@ do_poll(struct pollfd *fds, int nfds, int timeout_ticks)
fds[i].revents = 0;
if (fds[i].fd < 0)
continue; // negative fd: ignore, per poll(2)
if (fds[i].fd >= NOFILE || !myproc()->ofile[fds[i].fd]) {
if (fds[i].fd >= NOFILE || !myproc()->files->ofile[fds[i].fd]) {
fds[i].revents = POLLNVAL;
nready++;
continue;
}
int rev = file_poll(myproc()->ofile[fds[i].fd], fds[i].events);
int rev = file_poll(myproc()->files->ofile[fds[i].fd], fds[i].events);
if (rev) {
fds[i].revents = (short)rev;
nready++;
@ -217,7 +217,7 @@ sys_select(void)
int want_w = fdset_isset(wr, fd);
if (!want_r && !want_w)
continue;
struct file *f = myproc()->ofile[fd];
struct file *f = myproc()->files->ofile[fd];
if (!f)
return -EBADF;
int rev = file_poll(f, (want_r ? POLLIN : 0) | (want_w ? POLLOUT : 0));
@ -292,7 +292,7 @@ sys_pselect6(void)
int want_w = fdset_isset(wr, fd);
if (!want_r && !want_w)
continue;
struct file *f = myproc()->ofile[fd];
struct file *f = myproc()->files->ofile[fd];
if (!f)
return -EBADF;
int rev = file_poll(f, (want_r ? POLLIN : 0) | (want_w ? POLLOUT : 0));