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SubjectRe: [PATCH -mm 3/5][AIO] - export good_sigevent()
On Wed, Nov 29, 2006 at 11:32:34AM +0100, Sébastien Dugué 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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