Author: markj
Date: Tue Mar 31 02:25:53 2020
New Revision: 359477
URL: https://svnweb.freebsd.org/changeset/base/359477
Log:
Use a dedicated taskqueue thread for in6m_release_task().
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
Modified:
head/sys/netinet6/in6_mcast.c
Modified: head/sys/netinet6/in6_mcast.c
==============================================================================
--- head/sys/netinet6/in6_mcast.c Tue Mar 31 01:18:00 2020
(r359476)
+++ head/sys/netinet6/in6_mcast.c Tue Mar 31 02:25:53 2020
(r359477)
@@ -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
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