search

php / php-src

The PHP Interpreter
https://www.php.net
Other
38.29k stars 7.76k forks source link

Race conditions on tracing globals in jit-tracing mode in ZTS #16860

Open dktapps opened 6 days ago

dktapps commented 6 days ago

Description

While testing opcache.jit=tracing with a threading extension and valgrind --tool=drd, a good number of my extension's tests started detecting race conditions in zend_jit_trace_hot_root and some other places.

I'm seeing races in the following places: https://github.com/php/php-src/blob/PHP-8.3.13/ext/opcache/jit/zend_jit_trace.c#L7231 https://github.com/php/php-src/blob/PHP-8.3.13/ext/opcache/jit/zend_jit_trace.c#L7701 https://github.com/php/php-src/blob/PHP-8.3.13/ext/opcache/jit/zend_jit_trace.c#L7731 https://github.com/php/php-src/blob/PHP-8.3.13/ext/opcache/jit/zend_jit_trace.c#L8033 https://github.com/php/php-src/blob/PHP-8.3.13/ext/opcache/jit/zend_jit_trace.c#L8051

https://github.com/php/php-src/blob/PHP-8.3.13/ext/opcache/jit/zend_jit.c#L5096

https://github.com/php/php-src/blob/PHP-8.3.13/ext/opcache/jit/zend_jit_vm_helpers.c#L899

and a few other places

Vast majority seem to have zend_jit_trace_hot_root() in the stack traces

I have a whole bunch of test outputs from my CI if these are any help. Unfortunately the traces are a bit jumbled up in some cases for whatever reason.

Basically it looks like races may occur if two threads try to perform tracing JIT at the same time.

test-results-8.3.13-valgrind-drd-opcache-jit-tracing.zip from https://github.com/pmmp/ext-pmmpthread/actions/runs/11915925430/job/33207393626

PHP Version

8.3.13

Operating System

ubuntu-20.04 (GitHub Actions)