On Mon, 2 Apr 2007, Thomas Gleixner wrote:
> On Mon, 2007-04-02 at 10:30 -0700, Davide Libenzi wrote:
>
> > > There is no inaccuracy when you rearm the timer on read: hrtimer_forward
> > > takes care, that the period is accurate. It does not start the timer out
> > > of the periodic order, i.e. o
On Mon, 2007-04-02 at 10:30 -0700, Davide Libenzi wrote:
> > There is no inaccuracy when you rearm the timer on read: hrtimer_forward
> > takes care, that the period is accurate. It does not start the timer out
> > of the periodic order, i.e. on a different time frame.
> >
> > Where is the win of
On Mon, 2 Apr 2007, Thomas Gleixner wrote:
> The DoS is simple: create a bunch of periodic timers with 10usec period.
> This can be done by any user.
Ok, that's what I immagined. Agreed, that's a problem.
> There is no inaccuracy when you rearm the timer on read: hrtimer_forward
> takes care,
On Sun, 2007-04-01 at 10:00 -0700, Davide Libenzi wrote:
> > For periodic timers we probably want to know also about missed ticks,
> > i.e. when the timer was delayed.
> >
> > I changed recently the rearm handling code of itimers to prevent DoS
> > attacks. See commit 8bfd9a7a229b5f3d3eda5d7d45c2e
On Sun, 1 Apr 2007, Davide Libenzi wrote:
> I do not know about DoS on timers (did not follow the thread), but I could
> easily implement it here, by capping the counter to some value, and return
> POLLERR in poll().
For capping I mean, I won't re-arm the timer if ticks exceeded it ...
- Davi
On Sun, 1 Apr 2007, Thomas Gleixner wrote:
> On Sat, 2007-03-31 at 13:09 -0700, Davide Libenzi wrote:
> > +/*
> > + * This gets called when the timer event triggers. We increment the
> > + * tick count and wake the possible waiters. If the timer in a
> > + * sequential one (->tintv.tv64 != 0), we
On Sat, 2007-03-31 at 13:09 -0700, Davide Libenzi wrote:
> +/*
> + * This gets called when the timer event triggers. We increment the
> + * tick count and wake the possible waiters. If the timer in a
> + * sequential one (->tintv.tv64 != 0), we re-arm it with hrtimer_forward().
> + */
> +static enu
This patch introduces a new system call for timers events delivered
though file descriptors. This allows timer event to be used with
standard POSIX poll(2), select(2) and read(2). As a consequence of
supporting the Linux f_op->poll subsystem, they can be used with
epoll(2) too.
The system call is d
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