From 368104d06ad6d667a8cce152426916fc654b6627 Mon Sep 17 00:00:00 2001 From: Elias Rudberg Date: Thu, 16 Apr 2020 16:01:52 +0200 Subject: [PATCH] vlib: queue_hi_thresh fix to avoid deadlock Adapt queue_hi_thresh value using num_threads to avoid risk of deadlock between threads which could happen for example when different NAT threads try to handoff work to each other at the same time when their frame queues are congested. This change ensures that each thread can reserve a queue entry without causing problems even in the most extreme case when all threads attempt to add to the same queue simultaneously when the queue is nearly full. Type: fix Signed-off-by: Elias Rudberg Change-Id: I9e02f753bd00833d8dd500d181b0d4f9a454d703 --- src/vlib/threads.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/src/vlib/threads.c b/src/vlib/threads.c index a6915c5949b..82263797d93 100644 --- a/src/vlib/threads.c +++ b/src/vlib/threads.c @@ -1814,17 +1814,19 @@ vlib_frame_queue_main_init (u32 node_index, u32 frame_queue_nelts) vlib_frame_queue_main_t *fqm; vlib_frame_queue_t *fq; int i; + u32 num_threads; if (frame_queue_nelts == 0) frame_queue_nelts = FRAME_QUEUE_MAX_NELTS; - ASSERT (frame_queue_nelts >= 8); + num_threads = 1 /* main thread */ + tm->n_threads; + ASSERT (frame_queue_nelts >= 8 + num_threads); vec_add2 (tm->frame_queue_mains, fqm, 1); fqm->node_index = node_index; fqm->frame_queue_nelts = frame_queue_nelts; - fqm->queue_hi_thresh = frame_queue_nelts - 2; + fqm->queue_hi_thresh = frame_queue_nelts - num_threads; vec_validate (fqm->vlib_frame_queues, tm->n_vlib_mains - 1); vec_validate (fqm->per_thread_data, tm->n_vlib_mains - 1); -- 2.16.6