Re: [PATCH v4] app/testpmd: stop secondary process fwd_lcores during primary teardown

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 17 Sep 2025 04:36:01 -0700
Khadem Ullah <14pwcse1224@uetpeshawar.edu.pk> wrote:

> When the secondary process testpmd application running any fwd_engine
> and after that primary has exited will cause a crash.
> 
> This patch forces secondary process forwarding lcores
> in fwd_engine to stop before the primary process exits.
> 
> Fixes: a550baf24af90f ("app/testpmd: support multi-process")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Khadem Ullah <14pwcse1224@uetpeshawar.edu.pk>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---

There are still several issue left:
- using hotplug mp structs
- sending reply before fully exited.

Try this. It worked for simple quit and killing primary testpmd
with an ILL signal.



diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
index 0f58a31eb5..4c949adeda 100644
--- a/app/test-pmd/testpmd.c
+++ b/app/test-pmd/testpmd.c
@@ -46,6 +46,7 @@
 #include <rte_ether.h>
 #include <rte_ethdev.h>
 #include <rte_dev.h>
+#include <rte_stdatomic.h>
 #include <rte_string_fns.h>
 #include <rte_pci.h>
 #ifdef RTE_NET_IXGBE
@@ -3609,6 +3610,83 @@ detach_devargs(char *identifier)
 	rte_devargs_reset(&da);
 }
 
+#ifndef RTE_EXEC_ENV_WINDOWS
+
+enum testpmd_req_type {
+	TESTPMD_REQ_TYPE_EXIT,
+};
+
+struct testpmd_mp_req {
+	enum testpmd_req_type t;
+};
+
+struct testpmd_mp_resp {
+	int result;
+};
+
+#define TESTPMD_MP	"mp_testpmd"
+
+/* Send reply to this peer when testpmd exits */
+static RTE_ATOMIC(const char *) primary_name;
+
+static void
+reply_to_primary(const char *peer, int result)
+{
+	struct rte_mp_msg reply = { };
+	struct testpmd_mp_resp *resp = (struct testpmd_mp_resp *) &reply.param;
+
+	strlcpy(reply.name, TESTPMD_MP, RTE_MP_MAX_NAME_LEN);
+	reply.len_param = sizeof(*resp);
+	resp->result = result;
+
+	printf("Replying %d to primary\n", result);
+	fflush(stdout);
+
+	if (rte_mp_reply(&reply, peer) < 0)
+		printf("Failed to send response to primary:%s", strerror(rte_errno));
+}
+
+/* Primary process is exiting, stop secondary process */
+static void
+pmd_notify_secondary(void)
+{
+	struct testpmd_mp_req request = {
+		.t = TESTPMD_REQ_TYPE_EXIT,
+	};
+	struct rte_mp_msg mp_req = {
+		.name = TESTPMD_MP,
+		.len_param = sizeof(&request),
+	};
+	struct rte_mp_reply reply;
+	struct timespec ts = {.tv_sec = 5, .tv_nsec = 0};
+
+	printf("\nPrimary: Sending 'stop_req' request to secondary...\n");
+	fflush(stdout);
+
+	memcpy(mp_req.param, &request, sizeof(request));
+	rte_mp_request_sync(&mp_req, &reply, &ts);
+}
+
+static int
+handle_testpmd_request(const struct rte_mp_msg *request, const void *peer)
+{
+	const struct testpmd_mp_req *req = (const struct testpmd_mp_req *)request->param;
+
+	if (req->t == TESTPMD_REQ_TYPE_EXIT) {
+		printf("\nReceived notification of primary exiting\n");
+		fflush(stdout);
+
+		/* Response is sent after forwarding loop exits */
+		rte_atomic_store_explicit(&primary_name, peer, rte_memory_order_relaxed);
+
+		kill(getpid(), SIGINT);
+	} else {
+		reply_to_primary(peer, -EINVAL);
+	}
+	return 0;
+}
+#endif
+
 void
 pmd_test_exit(void)
 {
@@ -3620,6 +3698,10 @@ pmd_test_exit(void)
 		stop_packet_forwarding();
 
 #ifndef RTE_EXEC_ENV_WINDOWS
+	/* Tell secondary to exit */
+	if (rte_eal_process_type() == RTE_PROC_PRIMARY)
+		pmd_notify_secondary();
+
 	for (i = 0 ; i < RTE_DIM(mempools) ; i++) {
 		if (mempools[i]) {
 			if (mp_alloc_type == MP_ALLOC_ANON)
@@ -3628,6 +3710,7 @@ pmd_test_exit(void)
 		}
 	}
 #endif
+
 	if (ports != NULL) {
 		no_link_check = 1;
 		RTE_ETH_FOREACH_DEV(pt_id) {
@@ -4429,9 +4512,12 @@ main(int argc, char** argv)
 			 rte_strerror(rte_errno));
 
 #ifndef RTE_EXEC_ENV_WINDOWS
-	if (rte_eal_process_type() == RTE_PROC_SECONDARY &&
-	    enable_primary_monitor() < 0)
-		rte_exit(EXIT_FAILURE, "Cannot setup primary monitor");
+	if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
+		if (enable_primary_monitor() < 0)
+			rte_exit(EXIT_FAILURE, "Cannot setup primary monitor");
+		if (rte_mp_action_register(TESTPMD_MP, handle_testpmd_request) < 0)
+		    rte_exit(EXIT_FAILURE, "Failed to register message action\n");
+	}
 #endif
 
 	/* allocate port structures, and init them */
@@ -4628,12 +4714,23 @@ main(int argc, char** argv)
 	}
 
 #ifndef RTE_EXEC_ENV_WINDOWS
-	if (rte_eal_process_type() == RTE_PROC_SECONDARY)
+	if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
 		disable_primary_monitor();
+		rte_mp_action_unregister(TESTPMD_MP);
+	}
 #endif
-
 	pmd_test_exit();
 
+#ifndef RTE_EXEC_ENV_WINDOWS
+	if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
+		const char *peer
+			= rte_atomic_exchange_explicit(&primary_name, NULL, rte_memory_order_relaxed);
+		if (peer)
+			reply_to_primary(peer, 0);
+	}
+#endif
+
+
 #ifdef RTE_LIB_PDUMP
 	/* uninitialize packet capture framework */
 	rte_pdump_uninit();
-- 
2.47.3