preloading shutdown frees objects before module shutdown

Description

Since cecea72a10aa6470b3426a8d2f905f5ef2fe29b3, preloading executes zend_shutdown_executor_values() early in accel_preload() directly, causing zend_objects_store_free_object_storage() to be called long before php_request_shutdown() is called, which calls php_module_shutdown() - before zend_shutdown_executor_values, normally.

Can we bring consistency here between regular request shutdown and preloading shutdown, so that the latter needs no special handling?

This change led to a crash in our extension creating an object at rinit and accessing it in rshutdown: https://github.com/DataDog/dd-trace-php/issues/1795

==77== Invalid read of size 8
==77==    at 0x583BB80: ddtrace_close_all_open_spans (span.c:504)
==77==    by 0x582CAAB: zm_deactivate_ddtrace (ddtrace.c:897)
==77==    by 0x582CAAB: zm_deactivate_ddtrace (ddtrace.c:882)
==77==    by 0x51C81B: zend_deactivate_modules (in /usr/local/sbin/php-fpm)
==77==    by 0x4B0FB3: php_request_shutdown (in /usr/local/sbin/php-fpm)
==77==    by 0x56155FF: accel_finish_startup_preload (in /usr/local/lib/php/extensions/no-debug-non-zts-20210902/opcache.so)
==77==    by 0x5810D13: zai_interceptor_post_startup (interceptor.c:683)
==77==    by 0x515397: zend_post_startup (in /usr/local/sbin/php-fpm)
==77==    by 0x4B18DF: php_module_startup (in /usr/local/sbin/php-fpm)
==77==  Address 0x5a63b88 is 184 bytes inside a block of size 272 free'd
==77==    at 0x48C7488: free (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==77==    by 0x5B2B4B: zend_objects_store_del (in /usr/local/sbin/php-fpm)
==77==    by 0x5ADA7F: zend_object_std_dtor (in /usr/local/sbin/php-fpm)
==77==    by 0x5B2A3B: zend_objects_store_free_object_storage (in /usr/local/sbin/php-fpm)
==77==    by 0x504A17: zend_shutdown_executor_values (in /usr/local/sbin/php-fpm)
==77==    by 0x5613F5B: accel_preload (in /usr/local/lib/php/extensions/no-debug-non-zts-20210902/opcache.so)
==77==    by 0x56155CB: accel_finish_startup_preload (in /usr/local/lib/php/extensions/no-debug-non-zts-20210902/opcache.so)
==77==    by 0x5810D13: zai_interceptor_post_startup (interceptor.c:683)
==77==    by 0x515397: zend_post_startup (in /usr/local/sbin/php-fpm)
==77==    by 0x4B18DF: php_module_startup (in /usr/local/sbin/php-fpm)
==77==  Block was alloc'd at
==77==    at 0x48C4EC0: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==77==    by 0x4E6FB3: __zend_malloc (in /usr/local/sbin/php-fpm)
==77==    by 0x4EBA4F: _ecalloc (in /usr/local/sbin/php-fpm)
==77==    by 0x5828C8B: ddtrace_span_data_create (ddtrace.c:404)
==77==    by 0x5181EB: object_init_ex (in /usr/local/sbin/php-fpm)
==77==    by 0x583B063: ddtrace_init_span (span.c:247)
==77==    by 0x583B063: ddtrace_push_root_span (span.c:284)
==77==    by 0x582AA9B: zm_activate_ddtrace (ddtrace.c:834)
==77==    by 0x51C67F: zend_activate_modules (in /usr/local/sbin/php-fpm)
==77==    by 0x4B0BAB: php_request_startup (in /usr/local/sbin/php-fpm)

(ping @nikic being commit author)

PHP Version

PHP 8.1+

Operating System

No response

Bắt đầu bằng cách lần theo accel_preload() và zend_shutdown_executor_values(), sau đó so sánh thứ tự của chúng với php_request_shutdown() và php_module_shutdown(). Sử dụng kịch bản preload được báo cáo trên PHP 8.1+ và trace của Valgrind làm tham chiếu để tái hiện. Được xem là hoàn tất khi quá trình tắt preload không còn giải phóng các đối tượng trước khi đường dẫn tắt module cần đến chúng, mà không xảy ra lỗi đọc không hợp lệ đã được báo cáo.