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Date: Tue, 5 Dec 2006 09:30:03 +0100
From: =?ISO-8859-1?Q?S=E9bastien_Dugu=E9?= <sebastien.dugue@bull.net>
To: bharata@in.ibm.com
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>,
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       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: <20061205093003.620d8b1b@frecb000686>
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On Mon, 4 Dec 2006 22:43:13 +0530 Bharata B Rao <bharata@in.ibm.com> wrote:

> 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.

  That's right, I had to reflect that change into libposix-aio, i.e. transmuting
SIGEV_THREAD into SIGEV_SIGNAL.

  S?bastien.
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