RE: [BUG?] 2.6.x (2.6.13) - new signals not being delivered to a terminating (PF_EXITING) process.

From: linux-os (Dick Johnson)
Date: Tue Oct 11 2005 - 14:54:44 EST

On Tue, 11 Oct 2005, Kilau, Scott wrote:

>> Once a process in in the 'Z' state it should not receive any
>> signals. Its signal handlers are already gone. It's just a
>> snippit of sys_exit code that remains. If the process truly
>> is in the 'Z' state, its input/output/error file-descriptors
>> should have already been closed so the time-out from the
>> shutdown should have already happened.
> Hi Dick,
> You are right, its not a zombie.
> The process is held up in "drain" in the tty close of the
> processes stdin (/dev/ttyS0).
> (I assumed brackets in ps -ef meant zombies, but that's wrong)
> I added some code to make a short timeout in the "tty close" part of
> the driver, then check the values of:
> current->signal->
> current->signal->shared_pending.list.prev
> They *do* change, when I send the process (date) a signal.
> The kernel just isn't waking up the driver's "wait" to let it
> know that there are signals pending.

Okay. I have to take a "work break", but you can check the
driver and see if the code is interruptible (it must be)
and if there is something like if(signal_pending(current))
get_to_hell_out_of_this_loop.... in the time-out loop.

You can check against 2.4 code to see what's changed (a lot).
Sometimes with massive re-writes, simple things are forgotten.

> Also, why did this work under 2.4?
> This is why I was wondering if this was intentional, or was just an
> oversight...

The tty drivers were modified.

> Thanks!
> Scott

Dick Johnson
Penguin : Linux version on an i686 machine (5589.48 BogoMips).
Warning : 98.36% of all statistics are fiction.

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