83 lines
3.0 KiB
Diff
83 lines
3.0 KiB
Diff
commit 6c29942cbf059aca47fd4bbd852ea42c9d46b71f
|
|
Author: Stefan Liebler <stli@linux.ibm.com>
|
|
Date: Mon Feb 18 16:12:01 2019 +0100
|
|
|
|
misc/tst-clone3: Fix waiting for exited thread.
|
|
|
|
From time to time the test misc/tst-clone3 fails with a timeout.
|
|
Then futex_wait is blocking. Usually ctid should be set to zero
|
|
due to CLONE_CHILD_CLEARTID and the futex should be waken up.
|
|
But the fail occures if the thread has already exited before
|
|
ctid is set to the return value of clone(). Then futex_wait() will
|
|
block as there will be nobody who wakes the futex up again.
|
|
|
|
This patch initializes ctid to a known value before calling clone
|
|
and the kernel is the only one who updates the value to zero after clone.
|
|
If futex_wait is called then it is either waked up due to the exited thread
|
|
or the futex syscall fails as *ctid_ptr is already zero instead of the
|
|
specified value 1.
|
|
|
|
ChangeLog:
|
|
|
|
* sysdeps/unix/sysv/linux/tst-clone3.c (do_test):
|
|
Initialize ctid with a known value and remove update of ctid
|
|
after clone.
|
|
(wait_tid): Adjust arguments and call futex_wait with ctid_val
|
|
as assumed current value of ctid_ptr.
|
|
|
|
diff --git a/sysdeps/unix/sysv/linux/tst-clone3.c b/sysdeps/unix/sysv/linux/tst-clone3.c
|
|
index 784ce18f5343ec72..9f1ed6355e7acffd 100644
|
|
--- a/sysdeps/unix/sysv/linux/tst-clone3.c
|
|
+++ b/sysdeps/unix/sysv/linux/tst-clone3.c
|
|
@@ -27,6 +27,7 @@
|
|
|
|
#include <stackinfo.h> /* For _STACK_GROWS_{UP,DOWN}. */
|
|
#include <support/check.h>
|
|
+#include <stdatomic.h>
|
|
|
|
/* Test if clone call with CLONE_THREAD does not call exit_group. The 'f'
|
|
function returns '1', which will be used by clone thread to call the
|
|
@@ -42,11 +43,14 @@ f (void *a)
|
|
|
|
/* Futex wait for TID argument, similar to pthread_join internal
|
|
implementation. */
|
|
-#define wait_tid(tid) \
|
|
- do { \
|
|
- __typeof (tid) __tid; \
|
|
- while ((__tid = (tid)) != 0) \
|
|
- futex_wait (&(tid), __tid); \
|
|
+#define wait_tid(ctid_ptr, ctid_val) \
|
|
+ do { \
|
|
+ __typeof (*(ctid_ptr)) __tid; \
|
|
+ /* We need acquire MO here so that we synchronize with the \
|
|
+ kernel's store to 0 when the clone terminates. */ \
|
|
+ while ((__tid = atomic_load_explicit (ctid_ptr, \
|
|
+ memory_order_acquire)) != 0) \
|
|
+ futex_wait (ctid_ptr, ctid_val); \
|
|
} while (0)
|
|
|
|
static inline int
|
|
@@ -64,7 +68,11 @@ do_test (void)
|
|
clone_flags |= CLONE_VM | CLONE_SIGHAND;
|
|
/* We will used ctid to call on futex to wait for thread exit. */
|
|
clone_flags |= CLONE_CHILD_CLEARTID;
|
|
- pid_t ctid, tid;
|
|
+ /* Initialize with a known value. ctid is set to zero by the kernel after the
|
|
+ cloned thread has exited. */
|
|
+#define CTID_INIT_VAL 1
|
|
+ pid_t ctid = CTID_INIT_VAL;
|
|
+ pid_t tid;
|
|
|
|
#ifdef __ia64__
|
|
extern int __clone2 (int (*__fn) (void *__arg), void *__child_stack_base,
|
|
@@ -86,8 +94,7 @@ do_test (void)
|
|
if (tid == -1)
|
|
FAIL_EXIT1 ("clone failed: %m");
|
|
|
|
- ctid = tid;
|
|
- wait_tid (ctid);
|
|
+ wait_tid (&ctid, CTID_INIT_VAL);
|
|
|
|
return 2;
|
|
}
|