From 858151ff84848b3803f37983e4fe8bc450cb45ce Mon Sep 17 00:00:00 2001
From: Damjan Marion <damarion@cisco.com>
Date: Wed, 11 Jul 2018 10:51:00 +0200
Subject: threads: fix issue with setting main-core to 0

Change-Id: Id3ccfcfa2a88cf7aa106f1202af7cd677de32575
Signed-off-by: Damjan Marion <damarion@cisco.com>
---
 src/vlib/threads.c        | 21 ++++++++++++++-------
 src/vlib/threads.h        |  2 +-
 src/vpp/conf/startup.conf |  3 ++-
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/src/vlib/threads.c b/src/vlib/threads.c
index c17fde4bfec..a946326f239 100644
--- a/src/vlib/threads.c
+++ b/src/vlib/threads.c
@@ -337,10 +337,6 @@ vlib_thread_init (vlib_main_t * vm)
 
   avail_cpu = clib_bitmap_dup (tm->cpu_core_bitmap);
 
-  /* by default we skip core 0, unless it is the only one available */
-  if (tm->skip_cores == ~0)
-    tm->skip_cores = (clib_bitmap_count_set_bits (avail_cpu) < 2) ? 0 : 1;
-
   /* skip cores */
   for (i = 0; i < tm->skip_cores; i++)
     {
@@ -352,9 +348,13 @@ vlib_thread_init (vlib_main_t * vm)
     }
 
   /* grab cpu for main thread */
-  if (!tm->main_lcore)
+  if (tm->main_lcore == ~0)
     {
-      tm->main_lcore = clib_bitmap_first_set (avail_cpu);
+      /* if main-lcore is not set, we try to use lcore 1 */
+      if (clib_bitmap_get (avail_cpu, 1))
+	tm->main_lcore = 1;
+      else
+	tm->main_lcore = clib_bitmap_first_set (avail_cpu);
       if (tm->main_lcore == (u8) ~ 0)
 	return clib_error_return (0, "no available cpus to be used for the"
 				  " main thread");
@@ -376,6 +376,13 @@ vlib_thread_init (vlib_main_t * vm)
     {
       tm->cb.vlib_thread_set_lcore_cb (0, tm->main_lcore);
     }
+  else
+    {
+      cpu_set_t cpuset;
+      CPU_ZERO (&cpuset);
+      CPU_SET (tm->main_lcore, &cpuset);
+      pthread_setaffinity_np (pthread_self (), sizeof (cpu_set_t), &cpuset);
+    }
 
   /* as many threads as stacks... */
   vec_validate_aligned (vlib_worker_threads, vec_len (vlib_thread_stacks) - 1,
@@ -1259,7 +1266,7 @@ cpu_config (vlib_main_t * vm, unformat_input_t * input)
   tm->n_thread_stacks = 1;	/* account for main thread */
   tm->sched_policy = ~0;
   tm->sched_priority = ~0;
-  tm->skip_cores = ~0;
+  tm->main_lcore = ~0;
 
   tr = tm->next;
 
diff --git a/src/vlib/threads.h b/src/vlib/threads.h
index aaba218ffd3..f78ec1b9fa5 100644
--- a/src/vlib/threads.h
+++ b/src/vlib/threads.h
@@ -323,7 +323,7 @@ typedef struct
   u8 *thread_prefix;
 
   /* main thread lcore */
-  u8 main_lcore;
+  u32 main_lcore;
 
   /* Bitmap of available CPU cores */
   uword *cpu_core_bitmap;
diff --git a/src/vpp/conf/startup.conf b/src/vpp/conf/startup.conf
index c1ac1235861..34631aa8e0f 100644
--- a/src/vpp/conf/startup.conf
+++ b/src/vpp/conf/startup.conf
@@ -38,7 +38,8 @@ cpu {
 
 	## Manual pinning of thread(s) to CPU core(s)
 
-	## Set logical CPU core where main thread runs
+	## Set logical CPU core where main thread runs, if main core is not set
+	## VPP will use core 1 if available
 	# main-core 1
 
 	## Set logical CPU core(s) where worker threads are running
-- 
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