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Use a dedicated taskqueue thread for in6m_release_task().

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Interfaces may be detached from a taskqueue_thread task, for example by
prison_complete(), so after r359438, when draining the queue we may end
up deadlocking.

Reported by:	Jenkins via lwhsu
MFC with:	r359438
This commit is contained in:
Mark Johnston 2020-03-31 02:25:53 +00:00
parent adc0388117
commit 431f2b8712
1 changed files with 9 additions and 4 deletions
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13
sys/netinet6/in6_mcast.c
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@ -510,14 +510,19 @@ in6m_release(struct in6_multi *inm)
}
}
static struct task free_task;
/*
* Interface detach can happen in a taskqueue thread context, so we must use a
* dedicated thread to avoid deadlocks when draining in6m_release tasks.
*/
TASKQUEUE_DEFINE_THREAD(in6m_free);
static struct task in6m_free_task;
static struct in6_multi_head in6m_free_list = SLIST_HEAD_INITIALIZER();
static void in6m_release_task(void *arg __unused, int pending __unused);
static void
in6m_init(void)
{
TASK_INIT(&free_task, 0, in6m_release_task, NULL);
TASK_INIT(&in6m_free_task, 0, in6m_release_task, NULL);
}
SYSINIT(in6m_init, SI_SUB_TASKQ, SI_ORDER_ANY, in6m_init, NULL);
@ -529,13 +534,13 @@ in6m_release_list_deferred(struct in6_multi_head *inmh)
mtx_lock(&in6_multi_free_mtx);
SLIST_CONCAT(&in6m_free_list, inmh, in6_multi, in6m_nrele);
mtx_unlock(&in6_multi_free_mtx);
taskqueue_enqueue(taskqueue_thread, &free_task);
taskqueue_enqueue(taskqueue_in6m_free, &in6m_free_task);
}
void
in6m_release_wait(void)
{
taskqueue_drain_all(taskqueue_thread);
taskqueue_drain_all(taskqueue_in6m_free);
}
void