Fix dynamic instrumentation installation when enabling via dynamic config

bwoebi · bwoebi · commit 829e7dc6e654 · 2026-04-28T17:30:27.000+02:00
diff --git a/ext/configuration.c b/ext/configuration.c
@@ -176,7 +176,8 @@ static bool dd_parse_tags(zai_str value, zval *decoded_value, bool persistent) {
 #define INI_CHANGE_DYNAMIC_CONFIG(name, config) \
     static bool ddtrace_alter_##name(zval *old_value, zval *new_value, zend_string *new_str) { \
         UNUSED(old_value, new_value); \
-        if (!DDTRACE_G(remote_config_state)) {  \
+        /* When RC writes, bypass the check for ddog_remote_config_alter_dynamic_config */ \
+        if (!DDTRACE_G(remote_config_state) || DDTRACE_G(remote_config_writing)) {  \
             return true; \
         } \
         return ddog_remote_config_alter_dynamic_config(DDTRACE_G(remote_config_state), DDOG_CHARSLICE_C(config), zend_string_copy(new_str)); \
diff --git a/ext/ddtrace.h b/ext/ddtrace.h
@@ -154,6 +154,7 @@ ZEND_BEGIN_MODULE_GLOBALS(ddtrace)
     MUTEX_T sidecar_universal_service_tags_mutex;
     ddog_AgentRemoteConfigReader *agent_config_reader;
     ddog_RemoteConfigState *remote_config_state;
+    bool remote_config_writing; // true while RC WRITE mode INI update is in progress
     ddog_AgentInfoReader *agent_info_reader;
     dd_capture_arena debugger_capture_arena;
     ddog_Vec_DebuggerPayload exception_debugger_buffer;
diff --git a/ext/live_debugger.c b/ext/live_debugger.c
@@ -1668,7 +1668,8 @@ void ddtrace_live_debugger_minit(void) {
 bool ddtrace_alter_dynamic_instrumentation_config(zval *old_value, zval *new_value, zend_string *new_str) {
     UNUSED(old_value, new_str);
     bool enabled = Z_TYPE_P(new_value) == IS_TRUE;
-    if (DDTRACE_G(remote_config_state) && !ddog_remote_config_alter_dynamic_config(DDTRACE_G(remote_config_state), DDOG_CHARSLICE_C("datadog.dynamic_instrumentation.enabled"), zend_string_copy(new_str))) {
+    // When RC writes, bypass the check for ddog_remote_config_alter_dynamic_config
+    if (DDTRACE_G(remote_config_state) && !DDTRACE_G(remote_config_writing) && !ddog_remote_config_alter_dynamic_config(DDTRACE_G(remote_config_state), DDOG_CHARSLICE_C("datadog.dynamic_instrumentation.enabled"), zend_string_copy(new_str))) {
         return false;
     }
 
diff --git a/ext/remote_config.c b/ext/remote_config.c
@@ -99,10 +99,9 @@ static zend_string *dd_dynamic_configuration_update(ddog_CharSlice config, zend_
         }
     } else {
         ZEND_ASSERT(mode == DDOG_DYNAMIC_CONFIG_UPDATE_MODE_WRITE);
-        ddog_RemoteConfigState *saved = DDTRACE_G(remote_config_state);
-        DDTRACE_G(remote_config_state) = NULL;
+        DDTRACE_G(remote_config_writing) = true;
         zend_alter_ini_entry(name, value, ZEND_INI_USER, ZEND_INI_STAGE_RUNTIME);
-        DDTRACE_G(remote_config_state) = saved;
+        DDTRACE_G(remote_config_writing) = false;
         zend_string_release(value);
     }
     zend_string_release(name);

Original file line number	Diff line number	Diff line change
`@@ -1668,7 +1668,8 @@ void ddtrace_live_debugger_minit(void) {`
`1668`	`1668`	`bool ddtrace_alter_dynamic_instrumentation_config(zval old_value, zval new_value, zend_string *new_str) {`
`1669`	`1669`	`UNUSED(old_value, new_str);`
`1670`	`1670`	`bool enabled = Z_TYPE_P(new_value) == IS_TRUE;`
`1671`		`- if (DDTRACE_G(remote_config_state) && !ddog_remote_config_alter_dynamic_config(DDTRACE_G(remote_config_state), DDOG_CHARSLICE_C("datadog.dynamic_instrumentation.enabled"), zend_string_copy(new_str))) {`
	`1671`	`+ // When RC writes, bypass the check for ddog_remote_config_alter_dynamic_config`
	`1672`	`+ if (DDTRACE_G(remote_config_state) && !DDTRACE_G(remote_config_writing) && !ddog_remote_config_alter_dynamic_config(DDTRACE_G(remote_config_state), DDOG_CHARSLICE_C("datadog.dynamic_instrumentation.enabled"), zend_string_copy(new_str))) {`
`1672`	`1673`	`return false;`
`1673`	`1674`	`}`
`1674`	`1675`
Original file line number	Diff line number	Diff line change
`@@ -99,10 +99,9 @@ static zend_string *dd_dynamic_configuration_update(ddog_CharSlice config, zend_`
`99`	`99`	`}`
`100`	`100`	`} else {`
`101`	`101`	`ZEND_ASSERT(mode == DDOG_DYNAMIC_CONFIG_UPDATE_MODE_WRITE);`
`102`		`- ddog_RemoteConfigState *saved = DDTRACE_G(remote_config_state);`
`103`		`- DDTRACE_G(remote_config_state) = NULL;`
	`102`	`+ DDTRACE_G(remote_config_writing) = true;`
`104`	`103`	`zend_alter_ini_entry(name, value, ZEND_INI_USER, ZEND_INI_STAGE_RUNTIME);`
`105`		`- DDTRACE_G(remote_config_state) = saved;`
	`104`	`+ DDTRACE_G(remote_config_writing) = false;`
`106`	`105`	`zend_string_release(value);`
`107`	`106`	`}`
`108`	`107`	`zend_string_release(name);`