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Add thread_reap_barrier()

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Reviewed by:	hselasky,markj
Sponsored by:	Mellanox Technologies/NVidia Networking
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D30468
This commit is contained in:
Konstantin Belousov 2021-05-25 21:51:00 +03:00
parent 3a68546d23
commit f62c7e54e9
2 changed files with 33 additions and 0 deletions
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32
sys/kern/kern_thread.c
View File

@ -709,6 +709,38 @@ 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 thread *td;
struct task *t;
td = curthread;
/*
* 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.
*/

1
sys/sys/proc.h
View File

@ -1189,6 +1189,7 @@ 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);