From dd37fd6a49b41b12a0f9582bc72ae171aae29e1f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Sur=C3=BD?= <ondrej@isc.org>
Date: Wed, 4 Jun 2025 18:00:01 +0200
Subject: [PATCH] Add ISC_TID_MAX with default being 512 threads

The ISC_TID_MAX variable allows other units to declare static arrays
with this as size for per-thread/per-loop variables.
---
 bin/named/main.c          | 20 +++++++++++++++-----
 lib/isc/include/isc/tid.h |  4 ++++
 lib/isc/tid.c             |  2 ++
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/bin/named/main.c b/bin/named/main.c
index 14dee08c86..ae6f4fcc49 100644
--- a/bin/named/main.c
+++ b/bin/named/main.c
@@ -946,6 +946,8 @@ parse_command_line(int argc, char *argv[]) {
 
 static isc_result_t
 create_managers(void) {
+	bool capped = false;
+
 	/*
 	 * Set the default named_g_cpus if it was not set from the command line
 	 */
@@ -954,11 +956,19 @@ create_managers(void) {
 		named_g_cpus = named_g_cpus_detected;
 	}
 
-	isc_log_write(NAMED_LOGCATEGORY_GENERAL, NAMED_LOGMODULE_SERVER,
-		      ISC_LOG_INFO, "found %u CPU%s, using %u worker thread%s",
-		      named_g_cpus_detected,
-		      named_g_cpus_detected == 1 ? "" : "s", named_g_cpus,
-		      named_g_cpus == 1 ? "" : "s");
+	if (named_g_cpus > ISC_TID_MAX) {
+		capped = true;
+		named_g_cpus = ISC_TID_MAX;
+	}
+
+	isc_log_write(
+		NAMED_LOGCATEGORY_GENERAL, NAMED_LOGMODULE_SERVER, ISC_LOG_INFO,
+		"found %u CPU%s, using %u worker thread%s%s",
+		named_g_cpus_detected, named_g_cpus_detected == 1 ? "" : "s",
+		named_g_cpus, named_g_cpus == 1 ? "" : "s",
+		capped ? " (recompile with -DISC_TID_MAX=<n> to raise the "
+			 "thread count limit)"
+		       : "");
 
 	isc_managers_create(&named_g_mctx, named_g_cpus, &named_g_loopmgr,
 			    &named_g_netmgr);
diff --git a/lib/isc/include/isc/tid.h b/lib/isc/include/isc/tid.h
index b506205979..123e14092f 100644
--- a/lib/isc/include/isc/tid.h
+++ b/lib/isc/include/isc/tid.h
@@ -23,6 +23,10 @@ typedef int32_t isc_tid_t;
 
 #define ISC_TID_UNKNOWN (isc_tid_t) - 1
 
+#ifndef ISC_TID_MAX
+#define ISC_TID_MAX 512
+#endif /* ISC_TID_MAX */
+
 isc_tid_t
 isc_tid_count(void);
 /*%<
diff --git a/lib/isc/tid.c b/lib/isc/tid.c
index e8416a733c..909b4a949f 100644
--- a/lib/isc/tid.c
+++ b/lib/isc/tid.c
@@ -37,12 +37,14 @@ static isc_tid_t tid_count = 0;
 void
 isc__tid_init(isc_tid_t tid) {
 	REQUIRE(isc__tid_local == ISC_TID_UNKNOWN || isc__tid_local == tid);
+	REQUIRE(tid < ISC_TID_MAX);
 	isc__tid_local = tid;
 }
 
 void
 isc__tid_initcount(isc_tid_t count) {
 	REQUIRE(tid_count == 0 || tid_count == count);
+	REQUIRE(tid_count < ISC_TID_MAX);
 	tid_count = count;
 }