signal handler priority issue

[Sean McNeil]

On Fri, 2004-06-11 at 15:32, David Xu wrote:
> Sean McNeil wrote:
> 
> >On Fri, 2004-06-11 at 07:40, David Xu wrote:
> >  
> >
> >>Sean McNeil wrote:
> >>
> >>    
> >>
> >>>Sorry for top-posting, but it may be easier to read this way....
> >>>
> >>>The program below has an optimization bug in that done isn't declare
> >>>volatile.  With that fixed, it works just fine.  I've been attempting to
> >>>get boehm-gc working and it seems OK with libc_r, but fails with
> >>>libpthread.  It is essentially doing what the program below does, but
> >>>for some reason it gets stuck.  Has anyone else been experimenting with
> >>>boehm-gc?
> >>>
> >>>Also, it would really help if I had a debugger that worked with kse
> >>>threads.  How is that going?  Tracking down pthread issues right now has
> >>>been difficult with the current debugger.  Can anyone throw some patches
> >>>my way that may help?
> >>> 
> >>>
> >>>      
> >>>
> >>Please try the patch:
> >>http://people.freebsd.org/~davidxu/kse/thr_sigsuspend.c.diff
> >>
> >>the patch is for file /usr/src/lib/libpthread/thread/thr_sigsuspend.c,
> >>I believe I caught a bug in the sigsuspend(), thread
> >>should scan pending signals first, only when there is
> >>no pending signal in wait set,  the thread can sleep.
> >>    
> >>
> >
> >Also, the mask provided by the sigsuspend call should govern what
> >handlers get called.  So the sigmask should be left in place until after
> >the _thr_sig_check_pending(curthread) call.
> >
> >Thanks for catching this :)
> >
> >Sean
> >
> >
> >
> >
> >  
> >
> No the patch is still not correct, before
> _thr_sched_switch_unlocked(curthread) returns, signal will be delivered,
> so there needs a flag to tell signal dispatching code to use old signal mask
> when delivering signal to signal handler. I am working on it,
> thanks for your patch.

What old signal mask?  It should be the signals that sigsuspend allows
that get handled within sigsuspend.  Make sure the following can still
happen:

signal is masked.
sigsuspend is called with signal unmasked.
signal comes in or is pending already.
signal handler is called.
sigsuspend returns.

Sean