linux-kernel - Re: [PATCH -mm 4/7][AIO] Resend - Make good

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Date:	Mon, 5 Feb 2007 16:43:14 +0300
From:	Oleg Nesterov <oleg@...sign.ru>
To:	S?bastien Dugu? <sebastien.dugue@...l.net>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...l.org>, linux-aio <linux-aio@...ck.org>,
	Bharata B Rao <bharata@...ibm.com>,
	Christoph Hellwig <hch@...radead.org>,
	Suparna Bhattacharya <suparna@...ibm.com>,
	Ulrich Drepper <drepper@...hat.com>,
	Zach Brown <zach.brown@...cle.com>,
	Badari Pulavarty <pbadari@...ibm.com>,
	Benjamin LaHaise <bcrl@...ux.intel.com>,
	Jean Pierre Dion <jean-pierre.dion@...l.net>
Subject: Re: [PATCH -mm 4/7][AIO] Resend - Make good_sigevent() non-static

On 02/05, S?bastien Dugu? wrote:
> 
> +struct task_struct * sigevent_find_task(sigevent_t * event)
> +{
> +	struct task_struct *task = current->group_leader;
> +
> +	if ((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
> +		if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
> +			return NULL;
> +	}
> +
> +	if (event->sigev_notify & SIGEV_THREAD_ID) {
> +		if ((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL)
> +			return NULL;
> +
> +		task = find_task_by_pid(event->sigev_notify_thread_id);
> +
> +		if (!task || task->tgid != current->tgid)
> +			task = NULL;
> +	}
> +
> +	return task;
> +}

I think this patch is correct, and the code is much more readable than
the old good_sigevet().

But please don't forget that PATCH 6/7 still needs a small fixup, we can
leak a task_struct in really_put_req()

		if (notify == SIGEV_THREAD_ID || notify == SIGEV_SIGNAL)
			put_task_struct(req->ki_notify.target);

because without SIGEV_THREAD_ID ->sigev_notify can have any bit/bits set,
even SIGEV_NONE (along with some other bit, aio_setup_sigevent checks for
== SIGEV_NONE).

Oleg.

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