[LTP] [PATCH v2] fzsync: revoke thread_B when parent hit accidental break

[Li Wang]

Cyril Hrubis <chrubis@suse.cz> wrote:

> > +static void sighandler(int sig)
> > +{
> > +     if (sig == SIGUSR1)
> > +             pthread_exit(NULL);
> > +}
>
> As far as I can tell pthread_exit() is not async-signal-safe, so it
> shouldn't be called from signal context.

Right! This is really a good reminder.  Maybe we could use _exit() as
a replacement?

> > +/**
> > + * Wrap run_b for tst_fzsync_pair_reset to set the singal handler
> > + * at the start of the thread B.
> > + */
> > +static void *wrap_run_b(void * run_b)
> > +{
> > +     void *(*real_run_b)(void *) = run_b;
> > +
> > +     if (real_run_b) {
> > +             SAFE_SIGNAL(SIGUSR1, sighandler);
> > +             (*real_run_b)(NULL);
> > +     }
> > +
> > +     return NULL;
> > +}
>
> As far as I can tell the call to signal() will set the signal handler
> for all threads in the process, so there is no point in wrapping the run
> function like that, we can as well set up the signal handler before we
> start the b thread.

To wrap 'run_b' and set up signal handler only for that one thread is
to make things more precise, but as you pointed out it seems made an
unnecessary wrapping. Currently I don't have a perfect idea for
solving that and need thinking for a while. Anyway, if someone can
come up with a better solution that'd be appreciated.

-- 
Regards,
Li Wang