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authorElias Rudberg <elias.rudberg@bahnhof.net>2020-04-16 16:01:52 +0200
committerAndrew Yourtchenko <ayourtch@gmail.com>2020-08-13 17:20:47 +0000
commit99c6344d75ef002d9288d9c8d485fb961aee4de9 (patch)
treefb8e264bc0022c782b072988cb16d6d4544ad2be /src
parent2bd7f560c6377b3e48e69cfddd0c5b22abb9acd4 (diff)
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 <elias.rudberg@bahnhof.net> Change-Id: I9e02f753bd00833d8dd500d181b0d4f9a454d703 (cherry picked from commit 368104d06ad6d667a8cce152426916fc654b6627)
Diffstat (limited to 'src')
-rw-r--r--src/vlib/threads.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/src/vlib/threads.c b/src/vlib/threads.c
index 3488d70cec3..fe3a8746825 100644
--- a/src/vlib/threads.c
+++ b/src/vlib/threads.c
@@ -1837,17 +1837,19 @@ 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);