selftests/liveupdate: Add stress-sessions kexec test

Add a new test that creates 2000 LUO sessions before a kexec
reboot and verifies their presence after the reboot. This ensures
that the linked-block serialization mechanism works correctly for
a large number of sessions.

Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260603154402.468928-13-pasha.tatashin@soleen.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

diff --git a/tools/testing/selftests/liveupdate/Makefile b/tools/testing/selftests/liveupdate/Makefile
index 080754787ede644303256d9a43e407f93eb5a207..ed7534468386507dd177aefcdf1846c9bf36813c 100644 (file)
--- a/tools/testing/selftests/liveupdate/Makefile
+++ b/tools/testing/selftests/liveupdate/Makefile
@@ -6,6 +6,7 @@ TEST_GEN_PROGS += liveupdate
 
 TEST_GEN_PROGS_EXTENDED += luo_kexec_simple
 TEST_GEN_PROGS_EXTENDED += luo_multi_session
+TEST_GEN_PROGS_EXTENDED += luo_stress_sessions
 
 TEST_FILES += do_kexec.sh
 

diff --git a/tools/testing/selftests/liveupdate/luo_stress_sessions.c b/tools/testing/selftests/liveupdate/luo_stress_sessions.c
new file mode 100644 (file)
index 0000000..f201b18
--- /dev/null
+++ b/tools/testing/selftests/liveupdate/luo_stress_sessions.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright (c) 2026, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ *
+ * Validate that LUO can handle a large number of sessions across a kexec
+ * reboot.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include "luo_test_utils.h"
+
+#define NUM_SESSIONS 2000
+#define STATE_SESSION_NAME "kexec_many_state"
+#define STATE_MEMFD_TOKEN 999
+
+/* Stage 1: Executed before the kexec reboot. */
+static void run_stage_1(int luo_fd)
+{
+       int ret, i;
+
+       ksft_print_msg("[STAGE 1] Increasing ulimit for open files...\n");
+       ret = luo_ensure_nofile_limit(NUM_SESSIONS);
+       if (ret == -EPERM)
+               ksft_exit_skip("Insufficient privileges to set RLIMIT_NOFILE\n");
+       if (ret < 0)
+               ksft_exit_fail_msg("luo_ensure_nofile_limit failed: %s\n", strerror(-ret));
+
+       ksft_print_msg("[STAGE 1] Creating state file for next stage (2)...\n");
+       create_state_file(luo_fd, STATE_SESSION_NAME, STATE_MEMFD_TOKEN, 2);
+
+       ksft_print_msg("[STAGE 1] Creating %d sessions...\n", NUM_SESSIONS);
+
+       for (i = 0; i < NUM_SESSIONS; i++) {
+               char name[LIVEUPDATE_SESSION_NAME_LENGTH];
+               int s_fd;
+
+               snprintf(name, sizeof(name), "many-test-%d", i);
+               s_fd = luo_create_session(luo_fd, name);
+               if (s_fd < 0) {
+                       fail_exit("luo_create_session for '%s' at index %d",
+                                 name, i);
+               }
+       }
+
+       ksft_print_msg("[STAGE 1] Successfully created %d sessions.\n",
+                      NUM_SESSIONS);
+
+       close(luo_fd);
+       daemonize_and_wait();
+}
+
+/* Stage 2: Executed after the kexec reboot. */
+static void run_stage_2(int luo_fd, int state_session_fd)
+{
+       int i, stage;
+
+       ksft_print_msg("[STAGE 2] Starting post-kexec verification...\n");
+
+       restore_and_read_stage(state_session_fd, STATE_MEMFD_TOKEN, &stage);
+       if (stage != 2) {
+               fail_exit("Expected stage 2, but state file contains %d",
+                         stage);
+       }
+
+       ksft_print_msg("[STAGE 2] Retrieving and finishing %d sessions...\n",
+                      NUM_SESSIONS);
+
+       for (i = 0; i < NUM_SESSIONS; i++) {
+               char name[LIVEUPDATE_SESSION_NAME_LENGTH];
+               int s_fd;
+
+               snprintf(name, sizeof(name), "many-test-%d", i);
+               s_fd = luo_retrieve_session(luo_fd, name);
+               if (s_fd < 0) {
+                       fail_exit("luo_retrieve_session for '%s' at index %d",
+                                 name, i);
+               }
+
+               if (luo_session_finish(s_fd) < 0) {
+                       fail_exit("luo_session_finish for '%s' at index %d",
+                                 name, i);
+               }
+               close(s_fd);
+       }
+
+       ksft_print_msg("[STAGE 2] Finalizing state session...\n");
+       if (luo_session_finish(state_session_fd) < 0)
+               fail_exit("luo_session_finish for state session");
+       close(state_session_fd);
+
+       ksft_print_msg("\n--- MANY-SESSIONS KEXEC TEST PASSED (%d sessions) ---\n",
+                      NUM_SESSIONS);
+}
+
+int main(int argc, char *argv[])
+{
+       return luo_test(argc, argv, STATE_SESSION_NAME,
+                       run_stage_1, run_stage_2);
+}