diff options
author | nagachika <nagachika@ruby-lang.org> | 2021-06-03 20:46:53 +0900 |
---|---|---|
committer | nagachika <nagachika@ruby-lang.org> | 2021-06-03 20:46:53 +0900 |
commit | 2dd18df4a35a4b2dd0cf2dec7759898246fc6935 (patch) | |
tree | 9ec562b07900603960bc76f0ab7c669b9b281dba /mjit.c | |
parent | 9680ee97e0b3e87c0fc9a65c01de1ee50a1a178b (diff) |
merge revision(s) 86c262541ad07528842d76dab4b9b34bd888d5f4,7e14762159643b4415e094f9d2a90afaf7994588: [Backport #17935]
Fix a race condition around mjit_recompile
This fixes SEGVs like https://github.com/ruby/ruby/runs/2715166621?check_suite_focus=true.
When mjit_recompile is called when mjit_compile is compiling the exact
same iseq (and after it called mjit_capture_cc_entries), iseq->body->jit_unit
is re-created and its cc_entries becomes NULL. Then, when it tries to
lookup cc_entries through iseq->body->jit_unit, it fails.
---
mjit.c | 21 +++++++++++++--------
mjit_worker.c | 4 ++++
2 files changed, 17 insertions(+), 8 deletions(-)
Do not doubly hold an MJIT lock
This is a follow-up of 86c262541ad07528842d76dab4b9b34bd888d5f4.
CRITICAL_SECTION_START/FINISH are not needed when it's called from an
MJIT worker.
Also, ZALLOC needs to be calloc because ZALLOC may trigger GC, which an
MJIT worker must not do.
---
mjit.c | 23 ++++++++++++++---------
mjit_worker.c | 4 ++--
2 files changed, 16 insertions(+), 11 deletions(-)
Diffstat (limited to 'mjit.c')
-rw-r--r-- | mjit.c | 42 |
1 files changed, 26 insertions, 16 deletions
@@ -230,13 +230,13 @@ finish_conts(void) } } -// Create unit for `iseq`. +// Create unit for `iseq`. This function may be called from an MJIT worker. static void create_unit(const rb_iseq_t *iseq) { struct rb_mjit_unit *unit; - unit = ZALLOC(struct rb_mjit_unit); + unit = calloc(1, sizeof(struct rb_mjit_unit)); if (unit == NULL) return; @@ -245,8 +245,9 @@ create_unit(const rb_iseq_t *iseq) iseq->body->jit_unit = unit; } +// This is called from an MJIT worker when worker_p is true. static void -mjit_add_iseq_to_process(const rb_iseq_t *iseq, const struct rb_mjit_compile_info *compile_info) +mjit_add_iseq_to_process(const rb_iseq_t *iseq, const struct rb_mjit_compile_info *compile_info, bool worker_p) { if (!mjit_enabled || pch_status == PCH_FAILED) return; @@ -260,14 +261,18 @@ mjit_add_iseq_to_process(const rb_iseq_t *iseq, const struct rb_mjit_compile_inf if (compile_info != NULL) iseq->body->jit_unit->compile_info = *compile_info; - CRITICAL_SECTION_START(3, "in add_iseq_to_process"); + if (!worker_p) { + CRITICAL_SECTION_START(3, "in add_iseq_to_process"); + } add_to_list(iseq->body->jit_unit, &unit_queue); if (active_units.length >= mjit_opts.max_cache_size) { unload_requests++; } - verbose(3, "Sending wakeup signal to workers in mjit_add_iseq_to_process"); - rb_native_cond_broadcast(&mjit_worker_wakeup); - CRITICAL_SECTION_FINISH(3, "in add_iseq_to_process"); + if (!worker_p) { + verbose(3, "Sending wakeup signal to workers in mjit_add_iseq_to_process"); + rb_native_cond_broadcast(&mjit_worker_wakeup); + CRITICAL_SECTION_FINISH(3, "in add_iseq_to_process"); + } } // Add ISEQ to be JITed in parallel with the current thread. @@ -275,7 +280,7 @@ mjit_add_iseq_to_process(const rb_iseq_t *iseq, const struct rb_mjit_compile_inf void rb_mjit_add_iseq_to_process(const rb_iseq_t *iseq) { - mjit_add_iseq_to_process(iseq, NULL); + mjit_add_iseq_to_process(iseq, NULL, false); } // For this timeout seconds, --jit-wait will wait for JIT compilation finish. @@ -334,17 +339,22 @@ mjit_recompile(const rb_iseq_t *iseq) RSTRING_PTR(rb_iseq_path(iseq)), FIX2INT(iseq->body->location.first_lineno)); assert(iseq->body->jit_unit != NULL); - // Lazily move active_units to stale_units to avoid race conditions around active_units with compaction - CRITICAL_SECTION_START(3, "in rb_mjit_recompile_iseq"); - iseq->body->jit_unit->stale_p = true; - pending_stale_p = true; - CRITICAL_SECTION_FINISH(3, "in rb_mjit_recompile_iseq"); - - iseq->body->jit_func = (mjit_func_t)NOT_ADDED_JIT_ISEQ_FUNC; - mjit_add_iseq_to_process(iseq, &iseq->body->jit_unit->compile_info); if (UNLIKELY(mjit_opts.wait)) { + remove_from_list(iseq->body->jit_unit, &active_units); + add_to_list(iseq->body->jit_unit, &stale_units); + mjit_add_iseq_to_process(iseq, &iseq->body->jit_unit->compile_info, false); mjit_wait(iseq->body); } + else { + // Lazily move active_units to stale_units to avoid race conditions around active_units with compaction. + // Also, it's lazily moved to unit_queue as well because otherwise it won't be added to stale_units properly. + // It's good to avoid a race condition between mjit_add_iseq_to_process and mjit_compile around jit_unit as well. + CRITICAL_SECTION_START(3, "in rb_mjit_recompile_iseq"); + iseq->body->jit_unit->stale_p = true; + iseq->body->jit_func = (mjit_func_t)NOT_ADDED_JIT_ISEQ_FUNC; + pending_stale_p = true; + CRITICAL_SECTION_FINISH(3, "in rb_mjit_recompile_iseq"); + } } // Recompile iseq, disabling send optimization |