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mjit_worker.c: promote mjit_copy_job from function

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-local variable to global variable.

Consider this case:
1. MJIT worker: dequeue ISeq (stop_worker_p was still FALSE)
2. Ruby thread: call Kernel#exec, which calls mjit_finish(FALSE),
                sets `stop_worker_p = TRUE`, and fires RUBY_VM_CHECK_INTS() once
3. MJIT worker: register copy job, but found stop_worker_p is TRUE.
                set `worker_stopped = TRUE` and the thread stops.
4. Function-local job variable expires by the thread stop (this is eliminated by this commit)
5. Ruby thread: find `worker_stopped` becamse TRUE, start Kernel#exec.
                Kernel#exec fails but exception is rescued.
6. Ruby thread: call RUBY_VM_CHECK_INTS. copy job is dispatched but job variable
                is already expired.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66035 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
k0kubun 2018-11-27 12:00:51 +00:00
parent c3fe307808
commit 86cb3d319f
2 changed files with 24 additions and 20 deletions
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12
mjit.c
View file

@ -24,17 +24,17 @@
static void
mjit_copy_job_handler(void *data)
{
struct mjit_copy_job *job = data;
mjit_copy_job_t *job = data;
const struct rb_iseq_constant_body *body;
if (stop_worker_p) {
/* `copy_cache_from_main_thread()` stops to wait for this job. Then job data which is
allocated by `alloca()` could be expired and we might not be able to access that.
Also this should be checked before CRITICAL_SECTION_START to ensure that mutex is alive. */
if (stop_worker_p) { /* check if mutex is still alive, before calling CRITICAL_SECTION_START. */
return;
}
CRITICAL_SECTION_START(3, "in mjit_copy_job_handler");
/* Make sure that this job is never executed while job is being modified or ISeq is GC-ed */
/* Make sure that this job is never executed when:
1. job is being modified
2. alloca memory inside job is expired
3. ISeq is GC-ed */
if (job->finish_p || job->unit->iseq == NULL) {
CRITICAL_SECTION_FINISH(3, "in mjit_copy_job_handler");
return;

32
mjit_worker.c
View file

@ -1120,12 +1120,16 @@ convert_unit_to_func(struct rb_mjit_unit *unit, struct rb_call_cache *cc_entries
return (mjit_func_t)func;
}
struct mjit_copy_job {
typedef struct {
struct rb_mjit_unit *unit;
struct rb_call_cache *cc_entries;
union iseq_inline_storage_entry *is_entries;
int finish_p;
};
} mjit_copy_job_t;
/* Singleton MJIT copy job. This is made global since it needs to be durable even when MJIT worker thread is stopped.
(ex: register job -> MJIT pause -> MJIT resume -> dispatch job. Actually this should be just cancelled by finish_p check) */
static mjit_copy_job_t mjit_copy_job;
static void mjit_copy_job_handler(void *data);
@ -1133,7 +1137,7 @@ static void mjit_copy_job_handler(void *data);
could be different between ones on enqueue timing and ones on dequeue timing.
Return TRUE if copy succeeds. */
static int
copy_cache_from_main_thread(struct mjit_copy_job *job)
copy_cache_from_main_thread(mjit_copy_job_t *job)
{
CRITICAL_SECTION_START(3, "in copy_cache_from_main_thread");
job->finish_p = FALSE; /* allow dispatching this job in mjit_copy_job_handler */
@ -1164,7 +1168,7 @@ copy_cache_from_main_thread(struct mjit_copy_job *job)
void
mjit_worker(void)
{
struct mjit_copy_job job;
mjit_copy_job_t *job = &mjit_copy_job; /* just a shorthand */
#ifndef _MSC_VER
if (pch_status == PCH_NOT_READY) {
@ -1192,30 +1196,30 @@ mjit_worker(void)
verbose(3, "Getting wakeup from client");
}
unit = get_from_list(&unit_queue);
job.finish_p = TRUE; /* disable dispatching this job in mjit_copy_job_handler while it's being modified */
job->finish_p = TRUE; /* disable dispatching this job in mjit_copy_job_handler while it's being modified */
CRITICAL_SECTION_FINISH(3, "in worker dequeue");
if (unit) {
mjit_func_t func;
const struct rb_iseq_constant_body *body = unit->iseq->body;
job.unit = unit;
job.cc_entries = NULL;
job->unit = unit;
job->cc_entries = NULL;
if (body->ci_size > 0 || body->ci_kw_size > 0)
job.cc_entries = alloca(sizeof(struct rb_call_cache) * (body->ci_size + body->ci_kw_size));
job.is_entries = NULL;
job->cc_entries = alloca(sizeof(struct rb_call_cache) * (body->ci_size + body->ci_kw_size));
job->is_entries = NULL;
if (body->is_size > 0)
job.is_entries = alloca(sizeof(union iseq_inline_storage_entry) * body->is_size);
job->is_entries = alloca(sizeof(union iseq_inline_storage_entry) * body->is_size);
/* Copy ISeq's inline caches values to avoid race condition. */
if (job.cc_entries != NULL || job.is_entries != NULL) {
if (copy_cache_from_main_thread(&job) == FALSE) {
if (job->cc_entries != NULL || job->is_entries != NULL) {
if (copy_cache_from_main_thread(job) == FALSE) {
continue; /* retry postponed_job failure, or stop worker */
}
}
/* JIT compile */
func = convert_unit_to_func(unit, job.cc_entries, job.is_entries);
func = convert_unit_to_func(unit, job->cc_entries, job->is_entries);
CRITICAL_SECTION_START(3, "in jit func replace");
while (in_gc) { /* Make sure we're not GC-ing when touching ISeq */
@ -1240,7 +1244,7 @@ mjit_worker(void)
/* Disable dispatching this job in mjit_copy_job_handler while memory allocated by alloca
could be expired after finishing this function. */
job.finish_p = TRUE;
job->finish_p = TRUE;
/* To keep mutex unlocked when it is destroyed by mjit_finish, don't wrap CRITICAL_SECTION here. */
worker_stopped = TRUE;