[dpdk-dev] [PATCH] mem: fix deadlock on secondary allocation

[Anatoly Burakov <anatoly.burakov@intel.com>]

Previous fix used `rte_malloc_heap_socket_is_external()` to check if the
heap was an external heap. However, that API is thread-safe, and when
we're inside the allocation process, we're already write-locked, so
calling `rte_malloc_heap_socket_is_external()` will result in a
deadlock followed by a timeout.

Fix it by replacing the API call with a check against maximum number of
NUMA nodes, because external heaps always have higher socket ID's.

Fixes: 7ac31e82bc8f ("mem: improve parameter checking on memory hotplug")

Reported-by: Jim Harris <james.r.harris@intel.com>

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/librte_eal/common/malloc_mp.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/librte_eal/common/malloc_mp.c b/lib/librte_eal/common/malloc_mp.c
index 0b19d4d5fb..b1f7f7824b 100644
--- a/lib/librte_eal/common/malloc_mp.c
+++ b/lib/librte_eal/common/malloc_mp.c
@@ -241,8 +241,13 @@ handle_alloc_request(const struct malloc_mp_req *m,
 
 	heap = &mcfg->malloc_heaps[ar->malloc_heap_idx];
 
-	/* for allocations, we must only use internal heaps */
-	if (rte_malloc_heap_socket_is_external(heap->socket_id)) {
+	/*
+	 * for allocations, we must only use internal heaps, but since the
+	 * rte_malloc_heap_socket_is_external() is thread-safe and we're already
+	 * read-locked, we'll have to take advantage of the fac that internal
+	 * socket ID's are always lower than RTE_MAX_NUMA_NODES.
+	 */
+	if (heap->socket_id >= RTE_MAX_NUMA_NODES) {
 		RTE_LOG(ERR, EAL, "Attempting to allocate from external heap\n");
 		return -1;
 	}
-- 
2.25.1