Date: Mon, 7 Jun 2021 16:33:07 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 8c30192804eb - stable/13 - Add thread_reap_barrier() Message-ID: <202106071633.157GX7pL004169@gitrepo.freebsd.org>
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The branch stable/13 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=8c30192804eb91b2b976e92d0ca52fd034520062 commit 8c30192804eb91b2b976e92d0ca52fd034520062 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2021-05-25 18:51:00 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2021-06-07 16:32:42 +0000 Add thread_reap_barrier() (cherry picked from commit f62c7e54e9cc692603081328597ba0ba0d1f21cf) (cherry picked from commit d3f7975fcb346ea28dde079a9c04cff5ef20a8d7) --- sys/kern/kern_thread.c | 29 +++++++++++++++++++++++++++++ sys/sys/proc.h | 1 + 2 files changed, 30 insertions(+) diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c index 7370fd919203..48aac8e057b8 100644 --- a/sys/kern/kern_thread.c +++ b/sys/kern/kern_thread.c @@ -709,6 +709,35 @@ thread_reap_callout_cb(void *arg __unused) thread_reap_callout_cb, NULL); } +/* + * Calling this function guarantees that any thread that exited before + * the call is reaped when the function returns. By 'exited' we mean + * a thread removed from the process linkage with thread_unlink(). + * Practically this means that caller must lock/unlock corresponding + * process lock before the call, to synchronize with thread_exit(). + */ +void +thread_reap_barrier(void) +{ + struct task *t; + + /* + * First do context switches to each CPU to ensure that all + * PCPU pc_deadthreads are moved to zombie list. + */ + quiesce_all_cpus("", PDROP); + + /* + * Second, fire the task in the same thread as normal + * thread_reap() is done, to serialize reaping. + */ + t = malloc(sizeof(*t), M_TEMP, M_WAITOK); + TASK_INIT(t, 0, thread_reap_task_cb, t); + taskqueue_enqueue(taskqueue_thread, t); + taskqueue_drain(taskqueue_thread, t); + free(t, M_TEMP); +} + /* * Allocate a thread. */ diff --git a/sys/sys/proc.h b/sys/sys/proc.h index 7a2210778a39..b0fc13a449cb 100644 --- a/sys/sys/proc.h +++ b/sys/sys/proc.h @@ -1177,6 +1177,7 @@ int thread_create(struct thread *td, struct rtprio *rtp, void thread_exit(void) __dead2; void thread_free(struct thread *td); void thread_link(struct thread *td, struct proc *p); +void thread_reap_barrier(void); int thread_single(struct proc *p, int how); void thread_single_end(struct proc *p, int how); void thread_stash(struct thread *td);
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