Author: Armin Rigo <[email protected]>
Branch:
Changeset: r1313:1e16b1651dd4
Date: 2014-08-14 14:46 +0200
http://bitbucket.org/pypy/stmgc/changeset/1e16b1651dd4/
Log: Move the mutex locking outside rewind_setjmp.c, and remove some of
it, with some justification as comments.
diff --git a/c7/stm/core.c b/c7/stm/core.c
--- a/c7/stm/core.c
+++ b/c7/stm/core.c
@@ -328,8 +328,6 @@
{
assert(!_stm_in_transaction(tl));
- s_mutex_lock();
-
retry:
if (inevitable) {
wait_for_end_of_inevitable_transaction(tl);
@@ -390,6 +388,7 @@
long stm_start_transaction(stm_thread_local_t *tl)
{
+ s_mutex_lock();
#ifdef STM_NO_AUTOMATIC_SETJMP
long repeat_count = 0; /* test/support.py */
#else
@@ -401,6 +400,7 @@
void stm_start_inevitable_transaction(stm_thread_local_t *tl)
{
+ s_mutex_lock();
_stm_start_transaction(tl, true);
}
@@ -1077,6 +1077,7 @@
#ifdef STM_NO_AUTOMATIC_SETJMP
_test_run_abort(tl);
#else
+ s_mutex_lock();
stm_rewind_jmp_longjmp(tl);
#endif
}
diff --git a/c7/stm/rewind_setjmp.c b/c7/stm/rewind_setjmp.c
--- a/c7/stm/rewind_setjmp.c
+++ b/c7/stm/rewind_setjmp.c
@@ -4,12 +4,6 @@
#include <assert.h>
#include <alloca.h>
-#ifndef _STM_CORE_H_
-long _has_mutex() {return 1;}
-void s_mutex_lock() {}
-void s_mutex_unlock() {}
-#endif
-
struct _rewind_jmp_moved_s {
struct _rewind_jmp_moved_s *next;
@@ -42,8 +36,6 @@
void *ssstop;
size_t stack_size, ssstack_size;
- assert(_has_mutex());
-
assert(rjthread->head != NULL);
stop = rjthread->head->frame_base;
ssstop = rjthread->head->shadowstack_base;
@@ -98,11 +90,14 @@
rjthread->repeat_count = result;
/* snapshot of top frame: needed every time because longjmp() frees
- the previous one. Need to have mutex locked otherwise a concurrent
- GC may get garbage while saving shadow stack */
- s_mutex_lock();
+ the previous one. Note that this function is called with the
+ mutex already acquired. Although it's not the job of this file,
+ we assert it is indeed acquired here. This is needed, otherwise a
+ concurrent GC may get garbage while saving shadow stack */
+#ifdef _STM_CORE_H_
+ assert(_has_mutex());
+#endif
copy_stack(rjthread, (char *)&saved, saved.ss1);
- s_mutex_unlock();
return result;
}
@@ -114,7 +109,6 @@
current stack, expanding it if necessary. The shadowstack should
already be restored at this point (restore_shadowstack()) */
assert(rjthread->moved_off_base != NULL);
- s_mutex_lock();
while (rjthread->moved_off) {
struct _rewind_jmp_moved_s *p = rjthread->moved_off;
@@ -123,7 +117,6 @@
target -= p->stack_size;
if (target < stack_free) {
/* need more stack space! */
- s_mutex_unlock();
do_longjmp(rjthread, alloca(stack_free - target));
abort(); /* unreachable */
}
@@ -134,7 +127,12 @@
rj_free(p);
}
- s_mutex_unlock();
+#ifdef _STM_CORE_H_
+ /* This function must be called with the mutex held. It will
+ remain held across the longjmp that follows and into the
+ target rewind_jmp_setjmp() function. */
+ assert(_has_mutex());
+#endif
__builtin_longjmp(rjthread->jmpbuf, 1);
}
@@ -153,7 +151,9 @@
struct _rewind_jmp_moved_s *p = rjthread->moved_off;
char *sstarget = rjthread->moved_off_ssbase;
+#ifdef _STM_CORE_H_
assert(_has_mutex());
+#endif
while (p) {
if (p->shadowstack_size) {
@@ -178,21 +178,26 @@
{
/* called when leaving a frame. copies the now-current frame
to the list of stack-slices */
- s_mutex_lock();
+#ifdef _STM_CORE_H_
+ /* A transaction should be running now. This means in particular
+ that it's not possible that a major GC runs concurrently with
+ this code (and tries to read the shadowstack slice). */
+ assert(_seems_to_be_running_transaction());
+#endif
if (rjthread->head == NULL) {
_rewind_jmp_free_stack_slices(rjthread);
- s_mutex_unlock();
return;
}
assert(rjthread->moved_off_base < (char *)rjthread->head);
copy_stack(rjthread, rjthread->moved_off_base, rjthread->moved_off_ssbase);
- s_mutex_unlock();
}
void _rewind_jmp_free_stack_slices(rewind_jmp_thread *rjthread)
{
/* frees all saved stack copies */
- assert(_has_mutex());
+#ifdef _STM_CORE_H_
+ assert(_seems_to_be_running_transaction()); /* see previous function */
+#endif
struct _rewind_jmp_moved_s *p = rjthread->moved_off;
while (p) {
struct _rewind_jmp_moved_s *pnext = p->next;
_______________________________________________
pypy-commit mailing list
[email protected]
https://mail.python.org/mailman/listinfo/pypy-commit
