Hello,

I'm still very newby to kernel hacking, however while trying to port the
hrtimer-posix patch (which is now in the main tree) to ia64 I think I
came to find a bug.

Basically the problem is that while my program is in a pause() I can not
receive any signal > 32 (RT signals) even if I've just unblocked them.
In addition if I unblock signal 32 then all the RT signals are
unblocked. This strange behaviour is not reproductible during a sleep().
No idea came to my mind to test other system calls so I can't say more.

Attached to this email, there is a small program to highlight this
behaviour. The bug was reproductible under 2.4ia64 and 2.5ia64 but never
with an ia32 arch. To run it on your computer you compile it:
cc -Wall -DPAUSE -g bug_signal_rt.c -o bug_signal_rt

*and then run it as a background process (so you can send it some
signals):
>./bug_signal_rt &
[3] 15424
Testing SIGNAL1=33 with signal 32 unblocked.

*you send it a signal 33:
>kill -33 15424
The signal 33 was received.
Testing SIGNAL1=33 with signal 33 unblocked.

*send the signal 33:
>kill -33 15424
###nothing happens

So you can see the bug when it received the signal 33 while unblocking
only the signal 32!
If it's not so clear you can have a look at usage_bug_signal_rt.txt to
read a bit more.

Whatever, I tried to correct the bug but after reading
arch/ia64/kernel/signal.c I could find anything to help. My knowledge of
the kernel is still quite poor. So if someone could confirm the bug and
also give me some hints about where I should hunt this bug I would be
very grateful...

Cheers
Eric