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authornormal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2018-12-22 01:41:18 (GMT)
committernormal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2018-12-22 01:41:18 (GMT)
commit0fd53f519fb37b1dfe37be9f53ebc7889f405114 (patch)
tree9243e5b507696ebe7bdc28bcaf3626f95d724248
parent5072f03741087c869b2ded0c29349e9f3a361891 (diff)
thread_sync.c (rb_mutex_t): eliminate fork_gen
The true bug fork_gen was hiding was rb_mutex_abandon_locking_mutex failing to unconditionally clear the waitq of mutexes it was waiting on. So we fix rb_mutex_abandon_locking_mutex, instead, and eliminate rb_mutex_cleanup_keeping_mutexes. This commit was tested heavily on a single-core Pentium-M which was my most reliable reproducer of the "crash.rb" script from [Bug #15383] [Bug #14578] [Bug #15383] Note: [Bug #15430] turned out to be an entirely different problem: RLIMIT_NPROC limit was hit on the CI VMs. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66489 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
-rw-r--r--thread.c1
-rw-r--r--thread_sync.c41
2 files changed, 1 insertions, 41 deletions
diff --git a/thread.c b/thread.c
index faecec7..58e7651 100644
--- a/thread.c
+++ b/thread.c
@@ -4449,7 +4449,6 @@ rb_thread_atfork(void)
rb_thread_t *th = GET_THREAD();
rb_thread_atfork_internal(th, terminate_atfork_i);
th->join_list = NULL;
- rb_mutex_cleanup_keeping_mutexes(th);
rb_fiber_atfork(th);
/* We don't want reproduce CVE-2003-0900. */
diff --git a/thread_sync.c b/thread_sync.c
index dda92f1..4c253f0 100644
--- a/thread_sync.c
+++ b/thread_sync.c
@@ -45,17 +45,6 @@ typedef struct rb_mutex_struct {
rb_thread_t *th;
struct rb_mutex_struct *next_mutex;
struct list_head waitq; /* protected by GVL */
-
- /*
- * FIXME: belt-and-suspenders redundancy. This field should NOT
- * be necessary at all if:
- * - rb_mutex_cleanup_keeping_mutexes
- * - rb_mutex_abandon_keeping_mutexes
- * - rb_mutex_abandon_locking_mutex
- * are all correct, but I suspect one of them is buggy.
- * [Bug #15383] [Bug #15430]
- */
- rb_serial_t fork_gen;
} rb_mutex_t;
#if defined(HAVE_WORKING_FORK)
@@ -132,17 +121,9 @@ static rb_mutex_t *
mutex_ptr(VALUE obj)
{
rb_mutex_t *mutex;
- rb_serial_t fork_gen = GET_VM()->fork_gen;
TypedData_Get_Struct(obj, rb_mutex_t, &mutex_data_type, mutex);
- /* FIXME: remove (see comment at rb_mutex_t definition) */
- if (mutex->fork_gen != fork_gen) {
- /* forked children can't reach into parent thread stacks */
- mutex->fork_gen = fork_gen;
- list_head_init(&mutex->waitq);
- }
-
return mutex;
}
@@ -428,8 +409,7 @@ rb_mutex_abandon_locking_mutex(rb_thread_t *th)
if (th->locking_mutex) {
rb_mutex_t *mutex = mutex_ptr(th->locking_mutex);
- if (mutex->th == th)
- rb_mutex_abandon_all(mutex);
+ list_head_init(&mutex->waitq);
th->locking_mutex = Qfalse;
}
}
@@ -447,25 +427,6 @@ rb_mutex_abandon_all(rb_mutex_t *mutexes)
list_head_init(&mutex->waitq);
}
}
-
-/*
- * All other threads are dead in the a new child process, so waitqs
- * contain references to dead threads which we need to clean up
- */
-static void
-rb_mutex_cleanup_keeping_mutexes(const rb_thread_t *current_thread)
-{
- rb_mutex_t *mutex = current_thread->keeping_mutexes;
- rb_serial_t fork_gen = current_thread->vm->fork_gen;
-
- while (mutex) {
- /* FIXME: remove (see comment at rb_mutex_t definition) */
- mutex->fork_gen = fork_gen;
-
- list_head_init(&mutex->waitq);
- mutex = mutex->next_mutex;
- }
-}
#endif
static VALUE