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Date: Mon, 4 Dec 2006 22:43:13 +0530
From: Bharata B Rao <bharata@in.ibm.com>
To: =?iso-8859-1?Q?S=E9bastien_Dugu=E9?= <sebastien.dugue@bull.net>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
       linux-aio <linux-aio@kvack.org>, Andrew Morton <akpm@osdl.org>,
       Suparna Bhattacharya <suparna@in.ibm.com>,
       Christoph Hellwig <hch@infradead.org>,
       Zach Brown <zach.brown@oracle.com>,
       Badari Pulavarty <pbadari@us.ibm.com>,
       Ulrich Drepper <drepper@redhat.com>,
       Jean Pierre Dion <jean-pierre.dion@bull.net>
Subject: Re: [PATCH -mm 3/5][AIO] - export good_sigevent()
Message-ID: <20061204171313.GB27379@in.ibm.com>
Reply-To: bharata@in.ibm.com
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On Wed, Nov 29, 2006 at 11:32:34AM +0100, S?bastien Dugu? wrote:
> 
> <snip> 
> +/***
> + * good_sigevent - check and get target task from a sigevent.
> + * @event: the sigevent to be checked
> + *
> + * This function must be called with tasklist_lock held for reading.
> + */
> +struct task_struct * good_sigevent(sigevent_t * event)
> +{
> +	struct task_struct *rtn = current->group_leader;
> +
> +	if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
> +		(!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) ||
> +		 rtn->tgid != current->tgid ||
> +		 (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
> +		return NULL;
> +
> +	if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
> +	    ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
> +		return NULL;
> +
> +	return rtn;
> +}

Here good_sigevent() doesn't take care of SIGEV_THREAD. From this comment
from include/asm-generic/siginfo.h,

"It seems likely that SIGEV_THREAD will have to be handled from 
userspace, libpthread transmuting it to SIGEV_SIGNAL, which the
thread manager then catches and does the appropriate nonsense.
 However, everything is written out here so as to not get lost."

it looks like SIGEV_THREAD should never come into kernel. But atleast
libposix-aio does send SIGEV_THREAD all the way up to kernel.

Regards,
Bharata.
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