Date: Thu, 25 Apr 2024 13:46:44 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: d66399326cb4 - main - kthread: Set *tdptr earlier in kproc_kthread_add() Message-ID: <202404251346.43PDkihh043215@gitrepo.freebsd.org>
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The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=d66399326cb4f89d1565fb62c1c07974886893c5 commit d66399326cb4f89d1565fb62c1c07974886893c5 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2024-04-25 13:35:38 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2024-04-25 13:35:38 +0000 kthread: Set *tdptr earlier in kproc_kthread_add() See commit ae77041e0714 ("kthread: Set *newtdp earlier in kthread_add1()") for details. That commit was incomplete since g_init()'s first call to kproc_kthread_add() will cause kproc_kthread_add() to take the `*procptr == NULL` branch, which avoids kthread_create(). To ensure that the thread pointer is initialized before the thread starts running, we have to start the kernel process with RFSTOPPED. We could perhaps go further and use RFSTOPPED only when tdptr != NULL, but it's probably better to have consistent behaviour. Reviewed by: olce, kib Reported by: syzbot+e91e798f3c088215ace6@syzkaller.appspotmail.com MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D44927 --- sys/kern/kern_kthread.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/sys/kern/kern_kthread.c b/sys/kern/kern_kthread.c index 8a84fd70918d..97d10fdb394a 100644 --- a/sys/kern/kern_kthread.c +++ b/sys/kern/kern_kthread.c @@ -495,13 +495,21 @@ kproc_kthread_add(void (*func)(void *), void *arg, struct thread *td; if (*procptr == NULL) { + /* + * Use RFSTOPPED to ensure that *tdptr is initialized before the + * thread starts running. + */ error = kproc_create(func, arg, - procptr, flags, pages, "%s", procname); + procptr, flags | RFSTOPPED, pages, "%s", procname); if (error) return (error); td = FIRST_THREAD_IN_PROC(*procptr); if (tdptr) *tdptr = td; + if ((flags & RFSTOPPED) == 0) { + thread_lock(td); + sched_add(td, SRQ_BORING); + } va_start(ap, fmt); vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap); va_end(ap);
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