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.
On aarch64, alpha, arm, hppa, mips, nios2, powerpc, sh, sparc, tile,
and x86_64 the clone syscall jumps to _exit after the child execution
and the function ends the process execution by calling exit_group.
This behavior have a small issue where threads created with
CLONE_THREAD using clone syscall directly will eventually exit the
whole group altogether instead of just the thread created. Also,
s390, microblaze, ia64, i386, and m68k differs by calling exit
syscall directly.
This patch changes all architectures to call the exit syscall
directly, as for s390, microblaze, ia64, i386, and m68k. This do not
have change glibc internal behavior in any sort, since the only
usage of clone implementation in posix_spawn calls _exit directly
in the created child (fork uses a direct call to clone).
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
powerpc-linux-gnu, powerpc64le-linux-gnu, sparc64-linux-gnu,
and sparcv9-linux-gnu.
[BZ #21512]
* sysdeps/unix/sysv/linux/aarch64/clone.S (__clone): Call exit
syscall instead of jump to _exit.
(CLONE_VM_BIT): Remove unused define.
(CLONE_VM): Likewise.
(CLONE_THREAD_BIT): Likewise.
(CLONE_THREAD): Likewise.
* sysdeps/unix/sysv/linux/alpha/clone.S (__clone): Likewise.
(CLONE_VM): Remove unused define.
* sysdeps/unix/sysv/linux/arm/clone.S (__clone): Likewise.
(CLONE_VM): Remove unused define.
(CLONE_THREAD): Likewise.
* sysdeps/unix/sysv/linux/i386/clone.S (CLONE_VM): Likewise.
* sysdeps/unix/sysv/linux/ia64/clone2.S (__clone2): Call exit
syscall instead of jump to _exit.
* sysdeps/unix/sysv/linux/hppa/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/mips/clone.S (__clone): Likewise.
(CLONE_VM): Remove unused define.
(CLONE_THREAD): Likewise.
* sysdeps/unix/sysv/linux/nios2/clone.S (__clone): Likewise.
(CLONE_VM): Remove unused define.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S (__clone):
Likewise.
(CLONE_VM): Remove unused define.
(CLONE_THREAD): Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S (__clone):
Likewise.
(CLONE_VM): Remove unused define.
(CLONE_THREAD): Likewise.
* sysdeps/unix/sysv/linux/sh/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/clone.S (__clone): Likewise.
(CLONE_VM): Remove unused define.
* sysdeps/unix/sysv/linux/sparc/sparc64/clone.S (__clone): Likewise.
(CLONE_VM): Remove unused define.
* sysdeps/unix/sysv/linux/tile/clone.S (__clone): Likewise.
* sysdeps/unix/sysv/linux/x86_64/clone.S (__clone): Likewise.
(CLONE_VM): Remove unused define.
* sysdeps/unix/sysv/linux/Makefile (tests): Add tst-clone3.
* sysdeps/unix/sysv/linux/tst-clone3.c: New file.
Fix
