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merge revision(s) 62934,63210,63215,63309: [Backport #14634] 

thread_sync.c: avoid reaching across stacks of dead threads

	rb_ensure is insufficient cleanup for fork and we must
	reinitialize all waitqueues in the child process.

	Unfortunately this increases the footprint of ConditionVariable,
	Queue and SizedQueue by 8 bytes on 32-bit (16 bytes on 64-bit).

	[ruby-core:86316] [Bug #14634]

	variable.c: fix thread + fork errors in autoload

	This is fairly non-intrusive bugfix to prevent children
	from trying to reach into thread stacks of the parent.
	I will probably reuse this idea and redo r62934, too
	(same bug).

	* vm_core.h (typedef struct rb_vm_struct): add fork_gen counter
	* thread.c (rb_thread_atfork_internal): increment fork_gen
	* variable.c (struct autoload_data_i): store fork_gen
	* variable.c (check_autoload_data): remove (replaced with get_...)
	* variable.c (get_autoload_data): check fork_gen when retrieving
	* variable.c (check_autoload_required): use get_autoload_data
	* variable.c (rb_autoloading_value): ditto
	* variable.c (rb_autoload_p): ditto
	* variable.c (current_autoload_data): ditto
	* variable.c (autoload_reset): reset fork_gen, adjust indent
	* variable.c (rb_autoload_load): set fork_gen when setting state
	* test/ruby/test_autoload.rb (test_autoload_fork): new test
	  [ruby-core:86410] [Bug #14634]

	thread_sync: redo r62934 to use fork_gen

	Instead of maintaining linked-lists to store all
	rb_queue/rb_szqueue/rb_condvar structs; store only a fork_gen
	serial number to simplify management of these items.

	This reduces initialization costs and avoids the up-front cost
	of resetting all Queue/SizedQueue/ConditionVariable objects at
	fork while saving 8 bytes per-structure on 64-bit.  There are no
	savings on 32-bit.

	* thread.c (rb_thread_atfork_internal): remove rb_thread_sync_reset_all call
	* thread_sync.c (rb_thread_sync_reset_all): remove
	* thread_sync.c (queue_live): remove
	* thread_sync.c (queue_free): remove
	* thread_sync.c (struct rb_queue): s/live/fork_gen/
	* thread_sync.c (queue_data_type): use default free
	* thread_sync.c (queue_alloc): remove list_add
	* thread_sync.c (queue_fork_check): new function
	* thread_sync.c (queue_ptr): call queue_fork_check
	* thread_sync.c (szqueue_free): remove
	* thread_sync.c (szqueue_data_type): use default free
	* thread_sync.c (szqueue_alloc): remove list_add
	* thread_sync.c (szqueue_ptr):  check fork_gen via queue_fork_check
	* thread_sync.c (struct rb_condvar): s/live/fork_gen/
	* thread_sync.c (condvar_free): remove
	* thread_sync.c (cv_data_type): use default free
	* thread_sync.c (condvar_ptr): check fork_gen
	* thread_sync.c (condvar_alloc): remove list_add
	  [ruby-core:86316] [Bug #14634]

	thread_sync.c (condvar_ptr): reset fork_gen after forking

	Otherwise the condition variable waiter list will always
	be empty, which is wrong :x

	[Bug #14725] [Bug #14634]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@66912 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
nagachika 2019-01-23 14:14:25 +00:00
parent e42dcdb515
commit 63d9ab33fe
8 changed files with 162 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
test/ruby/test_autoload.rb
View File

@ -285,6 +285,32 @@ p Foo::Bar
end
end
def test_autoload_fork
EnvUtil.default_warning do
Tempfile.create(['autoload', '.rb']) {|file|
file.puts 'sleep 0.3; class AutoloadTest; end'
file.close
add_autoload(file.path)
begin
thrs = []
3.times do
thrs << Thread.new { AutoloadTest; nil }
thrs << Thread.new { fork { AutoloadTest } }
end
thrs.each(&:join)
thrs.each do |th|
pid = th.value or next
_, status = Process.waitpid2(pid)
assert_predicate status, :success?
end
ensure
remove_autoload_constant
assert_nil $!, '[ruby-core:86410] [Bug #14634]'
end
}
end
end if Process.respond_to?(:fork)
def add_autoload(path)
(@autoload_paths ||= []) << path
::Object.class_eval {autoload(:AutoloadTest, path)}

19
test/thread/test_cv.rb
View File

@ -217,4 +217,23 @@ INPUT
Marshal.dump(condvar)
end
end
def test_condvar_fork
mutex = Mutex.new
condvar = ConditionVariable.new
thrs = (1..10).map do
Thread.new { mutex.synchronize { condvar.wait(mutex) } }
end
thrs.each { 3.times { Thread.pass } }
pid = fork do
mutex.synchronize { condvar.broadcast }
exit!(0)
end
_, s = Process.waitpid2(pid)
assert_predicate s, :success?, 'no segfault [ruby-core:86316] [Bug #14634]'
until thrs.empty?
mutex.synchronize { condvar.broadcast }
thrs.delete_if { |t| t.join(0.01) }
end
end if Process.respond_to?(:fork)
end

48
test/thread/test_queue.rb
View File

@ -565,4 +565,52 @@ class TestQueue < Test::Unit::TestCase
puts 'exit'
INPUT
end
def test_fork_while_queue_waiting
q = Queue.new
sq = SizedQueue.new(1)
thq = Thread.new { q.pop }
thsq = Thread.new { sq.pop }
Thread.pass until thq.stop? && thsq.stop?
pid = fork do
exit!(1) if q.num_waiting != 0
exit!(2) if sq.num_waiting != 0
exit!(6) unless q.empty?
exit!(7) unless sq.empty?
q.push :child_q
sq.push :child_sq
exit!(3) if q.pop != :child_q
exit!(4) if sq.pop != :child_sq
exit!(0)
end
_, s = Process.waitpid2(pid)
assert_predicate s, :success?, 'no segfault [ruby-core:86316] [Bug #14634]'
q.push :thq
sq.push :thsq
assert_equal :thq, thq.value
assert_equal :thsq, thsq.value
sq.push(1)
th = Thread.new { q.pop; sq.pop }
thsq = Thread.new { sq.push(2) }
Thread.pass until th.stop? && thsq.stop?
pid = fork do
exit!(1) if q.num_waiting != 0
exit!(2) if sq.num_waiting != 0
exit!(3) unless q.empty?
exit!(4) if sq.empty?
exit!(5) if sq.pop != 1
exit!(0)
end
_, s = Process.waitpid2(pid)
assert_predicate s, :success?, 'no segfault [ruby-core:86316] [Bug #14634]'
assert_predicate thsq, :stop?
assert_equal 1, sq.pop
assert_same sq, thsq.value
q.push('restart th')
assert_equal 2, th.value
end if Process.respond_to?(:fork)
end

2
thread.c
View File

@ -4217,6 +4217,8 @@ rb_thread_atfork_internal(rb_thread_t *th, void (*atfork)(rb_thread_t *, const r
}
rb_vm_living_threads_init(vm);
rb_vm_living_threads_insert(vm, th);
vm->fork_gen++;
vm->sleeper = 0;
clear_coverage();
}

43
thread_sync.c
View File

@ -4,6 +4,14 @@
static VALUE rb_cMutex, rb_cQueue, rb_cSizedQueue, rb_cConditionVariable;
static VALUE rb_eClosedQueueError;
/*
* keep these globally so we can walk and reinitialize them at fork
* in the child process
*/
static LIST_HEAD(szqueue_list);
static LIST_HEAD(queue_list);
static LIST_HEAD(condvar_list);
/* sync_waiter is always on-stack */
struct sync_waiter {
rb_thread_t *th;
@ -556,6 +564,7 @@ void rb_mutex_allow_trap(VALUE self, int val)
#define queue_waitq(q) UNALIGNED_MEMBER_PTR(q, waitq)
PACKED_STRUCT_UNALIGNED(struct rb_queue {
struct list_head waitq;
rb_serial_t fork_gen;
const VALUE que;
int num_waiting;
});
@ -601,12 +610,29 @@ queue_alloc(VALUE klass)
return obj;
}
static int
queue_fork_check(struct rb_queue *q)
{
rb_serial_t fork_gen = GET_VM()->fork_gen;
if (q->fork_gen == fork_gen) {
return 0;
}
/* forked children can't reach into parent thread stacks */
q->fork_gen = fork_gen;
list_head_init(queue_waitq(q));
q->num_waiting = 0;
return 1;
}
static struct rb_queue *
queue_ptr(VALUE obj)
{
struct rb_queue *q;
TypedData_Get_Struct(obj, struct rb_queue, &queue_data_type, q);
queue_fork_check(q);
return q;
}
@ -649,6 +675,11 @@ szqueue_ptr(VALUE obj)
struct rb_szqueue *sq;
TypedData_Get_Struct(obj, struct rb_szqueue, &szqueue_data_type, sq);
if (queue_fork_check(&sq->q)) {
list_head_init(szqueue_pushq(sq));
sq->num_waiting_push = 0;
}
return sq;
}
@ -885,7 +916,7 @@ queue_do_pop(VALUE self, struct rb_queue *q, int should_block)
list_add_tail(&qw.as.q->waitq, &qw.w.node);
qw.as.q->num_waiting++;
rb_ensure(queue_sleep, Qfalse, queue_sleep_done, (VALUE)&qw);
rb_ensure(queue_sleep, self, queue_sleep_done, (VALUE)&qw);
}
}
@ -1127,7 +1158,7 @@ rb_szqueue_push(int argc, VALUE *argv, VALUE self)
list_add_tail(pushq, &qw.w.node);
sq->num_waiting_push++;
rb_ensure(queue_sleep, Qfalse, szqueue_sleep_done, (VALUE)&qw);
rb_ensure(queue_sleep, self, szqueue_sleep_done, (VALUE)&qw);
}
}
@ -1228,9 +1259,9 @@ rb_szqueue_empty_p(VALUE self)
/* ConditionalVariable */
/* TODO: maybe this can be IMEMO */
struct rb_condvar {
struct list_head waitq;
rb_serial_t fork_gen;
};
/*
@ -1277,9 +1308,15 @@ static struct rb_condvar *
condvar_ptr(VALUE self)
{
struct rb_condvar *cv;
rb_serial_t fork_gen = GET_VM()->fork_gen;
TypedData_Get_Struct(self, struct rb_condvar, &cv_data_type, cv);
/* forked children can't reach into parent thread stacks */
if (cv->fork_gen != fork_gen) {
list_head_init(&cv->waitq);
}
return cv;
}

32
variable.c
View File

@ -20,6 +20,7 @@
#include "ccan/list/list.h"
#include "id_table.h"
#include "debug_counter.h"
#include "vm_core.h"
struct rb_id_table *rb_global_tbl;
static ID autoload, classpath, tmp_classpath, classid;
@ -1859,6 +1860,7 @@ struct autoload_data_i {
rb_const_flag_t flag;
VALUE value;
struct autoload_state *state; /* points to on-stack struct */
rb_serial_t fork_gen;
};
static void
@ -1881,8 +1883,18 @@ static const rb_data_type_t autoload_data_i_type = {
0, 0, RUBY_TYPED_FREE_IMMEDIATELY
};
#define check_autoload_data(av) \
(struct autoload_data_i *)rb_check_typeddata((av), &autoload_data_i_type)
static struct autoload_data_i *
get_autoload_data(VALUE av)
{
struct autoload_data_i *ele = rb_check_typeddata(av, &autoload_data_i_type);
/* do not reach across stack for ->state after forking: */
if (ele && ele->state && ele->fork_gen != GET_VM()->fork_gen) {
ele->state = 0;
ele->fork_gen = 0;
}
return ele;
}
RUBY_FUNC_EXPORTED void
rb_autoload(VALUE mod, ID id, const char *file)
@ -1982,7 +1994,7 @@ check_autoload_required(VALUE mod, ID id, const char **loadingpath)
const char *loading;
int safe;
if (!(load = autoload_data(mod, id)) || !(ele = check_autoload_data(load))) {
if (!(load = autoload_data(mod, id)) || !(ele = get_autoload_data(load))) {
return 0;
}
file = ele->feature;
@ -2020,7 +2032,7 @@ rb_autoloading_value(VALUE mod, ID id, VALUE* value, rb_const_flag_t *flag)
VALUE load;
struct autoload_data_i *ele;
if (!(load = autoload_data(mod, id)) || !(ele = check_autoload_data(load))) {
if (!(load = autoload_data(mod, id)) || !(ele = get_autoload_data(load))) {
return 0;
}
if (ele->state && ele->state->thread == rb_thread_current()) {
@ -2087,8 +2099,9 @@ autoload_reset(VALUE arg)
int need_wakeups = 0;
if (state->ele->state == state) {
need_wakeups = 1;
state->ele->state = 0;
need_wakeups = 1;
state->ele->state = 0;
state->ele->fork_gen = 0;
}
/* At the last, move a value defined in autoload to constant table */
@ -2170,7 +2183,7 @@ rb_autoload_load(VALUE mod, ID id)
if (src && loading && strcmp(src, loading) == 0) return Qfalse;
/* set ele->state for a marker of autoloading thread */
if (!(ele = check_autoload_data(load))) {
if (!(ele = get_autoload_data(load))) {
return Qfalse;
}
@ -2180,6 +2193,7 @@ rb_autoload_load(VALUE mod, ID id)
state.thread = rb_thread_current();
if (!ele->state) {
ele->state = &state;
ele->fork_gen = GET_VM()->fork_gen;
/*
* autoload_reset will wake up any threads added to this
@ -2217,7 +2231,7 @@ rb_autoload_p(VALUE mod, ID id)
}
load = check_autoload_required(mod, id, 0);
if (!load) return Qnil;
return (ele = check_autoload_data(load)) ? ele->feature : Qnil;
return (ele = get_autoload_data(load)) ? ele->feature : Qnil;
}
void
@ -2646,7 +2660,7 @@ current_autoload_data(VALUE mod, ID id)
struct autoload_data_i *ele;
VALUE load = autoload_data(mod, id);
if (!load) return 0;
ele = check_autoload_data(load);
ele = get_autoload_data(load);
if (!ele) return 0;
/* for autoloading thread, keep the defined value to autoloading storage */
if (ele->state && (ele->state->thread == rb_thread_current())) {

6
version.h
View File

@ -1,10 +1,10 @@
#define RUBY_VERSION "2.5.4"
#define RUBY_RELEASE_DATE "2019-01-20"
#define RUBY_PATCHLEVEL 137
#define RUBY_RELEASE_DATE "2019-01-23"
#define RUBY_PATCHLEVEL 138
#define RUBY_RELEASE_YEAR 2019
#define RUBY_RELEASE_MONTH 1
#define RUBY_RELEASE_DAY 20
#define RUBY_RELEASE_DAY 23
#include "ruby/version.h"

1
vm_core.h
View File

@ -507,6 +507,7 @@ typedef struct rb_vm_struct {
struct rb_thread_struct *main_thread;
struct rb_thread_struct *running_thread;
rb_serial_t fork_gen;
struct list_head waiting_fds; /* <=> struct waiting_fd */
struct list_head living_threads;
size_t living_thread_num;