Hi David,

quoted

diff --git a/lib/librte_eal/common/eal_common_lcore.c b/lib/librte_eal/common/eal_common_lcore.c
index 86d32a3dd7..7db05428e7 100644
--- a/lib/librte_eal/common/eal_common_lcore.c
+++ b/lib/librte_eal/common/eal_common_lcore.c

@@ -6,12 +6,13 @@
 #include <limits.h>
 #include <string.h>

-#include <rte_errno.h>
-#include <rte_log.h>
-#include <rte_eal.h>
-#include <rte_lcore.h>
 #include <rte_common.h>
 #include <rte_debug.h>
+#include <rte_eal.h>
+#include <rte_errno.h>
+#include <rte_lcore.h>
+#include <rte_log.h>
+#include <rte_spinlock.h>

 #include "eal_private.h"
 #include "eal_thread.h"

@@ -220,3 +221,38 @@ rte_socket_id_by_idx(unsigned int idx)
 	}
 	return config->numa_nodes[idx];
 }
+
+static rte_spinlock_t lcore_lock = RTE_SPINLOCK_INITIALIZER;
+
+unsigned int
+eal_lcore_non_eal_allocate(void)
+{
+	struct rte_config *cfg = rte_eal_get_configuration();
+	unsigned int lcore_id;
+
+	rte_spinlock_lock(&lcore_lock);

I think it will break current DPDK MP modes.
The problem here - rte_config (and lcore_role[]) is in shared memory,
while the lock is local.
Simplest way probably to move lcore_lock to rte_config.

Actually sorry, I was wrong - rte_config is local.
So having lcore_lock local seems ok here.
Though then, I think another issue arises:
For MP case 2 processes might get the same lcore_id via this function. 
And, as I remember, rte_mempool cache is by default located in shared memory.
So two threads might end-up racing for the same mempool cache slot.
Same story probably about some other shared data that uses lcore_id as an index

quoted

+	for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
+		if (cfg->lcore_role[lcore_id] != ROLE_OFF)
+			continue;
+		cfg->lcore_role[lcore_id] = ROLE_NON_EAL;
+		cfg->lcore_count++;
+		break;
+	}
+	if (lcore_id == RTE_MAX_LCORE)
+		RTE_LOG(DEBUG, EAL, "No lcore available.\n");
+	rte_spinlock_unlock(&lcore_lock);
+	return lcore_id;
+}
+
+void
+eal_lcore_non_eal_release(unsigned int lcore_id)
+{
+	struct rte_config *cfg = rte_eal_get_configuration();
+
+	rte_spinlock_lock(&lcore_lock);
+	if (cfg->lcore_role[lcore_id] == ROLE_NON_EAL) {
+		cfg->lcore_role[lcore_id] = ROLE_OFF;
+		cfg->lcore_count--;
+	}
+	rte_spinlock_unlock(&lcore_lock);
+}