On Wed, 2013-11-20 at 04:11 -0500, Jan Stancek wrote:
> > +static int child_clone_parent()
> > +{
> > + usleep(500000);
> > + if (parent_ppid == getppid())
> > + kill(tgid, SIG_PASS);
> > + else
> > + kill(tgid, SIG_FAIL);
> > + exit(PASS);
> > +}
>
> Hi,
>
> why not just exit with either PASS or FAIL and parent can check the status?
> You wouldn't need sleep or signals.
>
> If you need parent/child synchronization, then consider "checkpoints"
> (lib/tst_checkpoint.c)
>
There is a little different with CLONE_PARENT. The exit value can't be
easily gained by the calling process(after CLONE_PARENT, they are not
really parent and child, maybe brothers precise).
wait(&status); /* It will faile because of no child. */
if (WIFEXITED(status) && WEXITSTATUS(status) == PASS)
...
> > +#ifdef CLONE_STOPPED
> > +static void test_clone_stopped(int tid)
> > +{
> > + int i;
> > +
> > + /* give the kernel scheduler chance to run the child */
> > + for (i = 0; i < 100; i++) {
> > + sched_yield();
> > + usleep(1000);
> > + }
> > + if (thread_state == 0)
>
> Does the child have even chance to change this value in parent without
> CLONE_VM?
>
Yes, we should add CLONE_VM.
> > + tst_resm(TPASS, "test CLONE_STOPPED success");
> > + else
> > + tst_resm(TFAIL, "test CLONE_STOPPED fail");
> > +
> > + if (kill(tid, SIGCONT) != 0)
> > + tst_brkm(TBROK | TERRNO, cleanup, "kill SIGCONT failed");
> > +}
> > +
> > +static int child_clone_stopped()
> > +{
> > + thread_state = 1;
>
> thread_state should be reset to 0 before this test, in case you run it in
> loop (-i parameter).
>
Yes, thread_state should be reset to 0 at the begin of the loop.
> > + exit(PASS);
> > +}
> > +#endif
> > +
> > +static int child_clone_thread(void)
> > +{
> > + pid_t child_tgid;
> > +
> > + child_tgid = getpid();
> > +
> > + if (tgid == child_tgid)
> > + kill(tgid, SIG_PASS);
> > + else
> > + kill(tgid, SIG_FAIL);
> > + usleep(500000);
> > + exit(PASS);
> > +}
>
> Same as above, why not just return PASS or FAIL and check status in parent?
>
When a CLONE_THREAD thread terminates, the thread that created it using
clone() is not sent a SIGCHLD (or other termination) signal; nor can the
status of such a thread be obtained using wait(2). (The thread is said to
be detached.)
best regards,
Zeng
> Regards,
> Jan
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