Re: RFA: Fix lin-lwp SIGINT handling for 2.6

[Michael Snyder <msnyder@redhat.com>]

Daniel Jacobowitz wrote:
> On Tue, Aug 26, 2003 at 07:22:13PM -0700, Michael Snyder wrote:
> 
>>Daniel Jacobowitz wrote:
>>
>>>This patch fixes a number of inconsistent regressions in schedlock.exp and
>>>pthreads.exp on 2.6-series kernels, using LinuxThreads.  Red Hat 2.4 
>>>kernels
>>>have the same problems; the fix will work there too iff there is an update
>>>which exports ShdPnd in /proc.
>>>
>>>The problem is that the SIGINT is delivered to every thread, and not
>>>properly flushed.  So we go later to step or continue and get an "echo" of
>>>the original SIGINT.  This is a timing problem caused by the introduction 
>>>of
>>>two signal queues in the kernel; the SIGSTOP is now guaranteed to be
>>>delivered before the SIGINT, since it's on the thread-specific queue.  It
>>>used to be that SIGINT would be delivered first; they were on the same
>>>queue, and SIGINT was lower numbered.
>>>
>>>So we have to check whether a SIGINT is pending (and not blocked/ignored)
>>>for the current thread after we stop it, and resume the thread to catch the
>>>SIGINT if so.
>>>
>>>It's not a perfect fix, but it's enough more reliable than the current
>>>scheme that I haven't been able to reproduce the problems.  OK?  HEAD only;
>>>this is a bit of an annoyance, but too risky for the branch, IMO.
>>>
>>
>>I've been worried about that.
>>
>>May I suggest that the function that opens a proc file belongs
>>in linux-proc.c?
> 
> 
> It is in linux-proc.c :)
> 
>         * linux-proc.c (linux_proc_add_line_to_sigset): New function.
>         (linux_proc_pending_signals): New function.
>         * linux-nat.h (linux_proc_pending_signals): Add prototype

Oh.  Well then -- never mind.  ;-)
Speaking as the originator of linux-proc.c, it's fine with me
to put it there.  I don't feel competent to judge the correctness
of the code, though.


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