From: "Stuart MacDonald" <stuartm@connecttech.com>
To: "'Linux Kernel Mailing List'" <linux-kernel@vger.kernel.org>
Subject: Proper use of daemonize()?
Date: Wed, 6 Oct 2004 11:18:07 -0400
Organization: Connect Tech Inc.
Message-ID: <030601c4abb7$af573770$294b82ce@stuartm>
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I've been looking at the kernel threads that use daemonize() and have
some questions about the proper use of this call:

1: Some threads use the lock_kernel() calls around the daemonize()
call. Is this necessary? I thought the BKL was phasing out.

2: Some threads do their setup (like changing the comm string, setting
the signal masks, etc) before daemonize(), some do it after. Is there
any benefit to a particular order of operations? I can't see one.

3: Some threads set current->tty to NULL. Why would a thread *not* do
this?

4: Some threads grab the sigmask_lock before manipulating their masks.
Is this necessary? If so, some threads have bugs. If not, why do some
threads bother?

5: Some threads do flush_signals() or recalc_sigpending() before
updating their blocked mask, some do it after. Does the order matter?
I suspect not.

6: MOD_INC_USE_COUNT should be used by all threads that could be in
drivers built as modules, correct?

7: If you're not spawning a permanent kernel thread (like kswapd frex)
is the any benefit to using reparent_to_init()? I can't see one.

Thanks,
..Stu

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