linux-kernel - Re: [PATCH v2 4/4] copy_signal cleanup: clean tty_audit

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Message-ID: <20091205165804.GD23152@redhat.com>
Date:	Sat, 5 Dec 2009 17:58:04 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Veaceslav Falico <vfalico@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Greg Kroah-Hartman <gregkh@...e.de>,
	Al Viro <viro@...iv.linux.org.uk>,
	Miloslav Trmac <mitr@...hat.com>,
	James Morris <jmorris@...ei.org>,
	Alan Cox <alan@...ux.intel.com>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Renaud Lottiaux <renaud.lottiaux@...labs.com>,
	Louis Rilling <louis.rilling@...labs.com>,
	David Howells <dhowells@...hat.com>,
	Stanislaw Gruszka <sgruszka@...hat.com>
Subject: Re: [PATCH v2 4/4] copy_signal cleanup: clean tty_audit_fork()

On 12/04, Veaceslav Falico wrote:
>
> Remove unneeded initialization in tty_audit_fork().
> It is called only via copy_signal() and is useless after
> the kmem_cache_zalloc() was used.
>
> Signed-off-by: Veaceslav Falico <vfalico@...hat.com>
> ---
>
> diff --git a/drivers/char/tty_audit.c b/drivers/char/tty_audit.c
> index ac16fbe..283a15b 100644
> --- a/drivers/char/tty_audit.c
> +++ b/drivers/char/tty_audit.c
> @@ -148,7 +148,6 @@ void tty_audit_fork(struct signal_struct *sig)
>  	spin_lock_irq(&current->sighand->siglock);
>  	sig->audit_tty = current->signal->audit_tty;
>  	spin_unlock_irq(&current->sighand->siglock);
> -	sig->tty_audit_buf = NULL;
>  }

Can't comment the changes in audit code, but the patch looks obviously
correct.



Off-topic question to this who understands this code.

But afaics we can also remove ->siglock from this helper and make
it really trivial for being inline. ->siglock buys nothing, we just
read a boolean. In fact, after the quick grep I do not understand
how ->siglock is connected to ->audit_tty. OK, it protects tty_audit_buf,
but why we always take ->siglock to access ->audit_tty ?

Oleg.

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