On Tue, Jun 10, 2014 at 1:03 PM, Michael Kerrisk (man-pages) <mtk.manpages@xxxxxxxxx> wrote: > [CC += linux-api@] > > On Tue, Jun 10, 2014 at 6:35 PM, Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote: >> On Thu, May 22, 2014 at 06:58:19AM +0900, Thomas Gleixner wrote: >>> > >>> > So what wakes a potential waiter in read/poll? >>> >>> And who is updating timerfd_create(2) ? >> >> Thomas, could you please take a look if the approach below is acceptable? >> If it will be fine I update manpage then. >> --- >> From: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> >> Subject: timerfd: Implement timerfd_ioctl method to restore timerfd_ctx::ticks >> >> The read() of timerfd files allows to fetch the number of timer ticks >> while there is no way to set it back from userspace. >> >> To restore the timer's state as it was at checkpoint moment we need >> a path to bring @ticks back. Initially I thought about writing ticks >> back via write() interface but it seems such API is somehow obscure. >> >> Instead implement timerfd_ioctl() method with TFD_IOC_SET_TICKS >> command which requires CAP_SYS_RESOURCE capability to be able to >> set @ticks into arbitrary value. Note this command doesn't wake >> up readers/waiters and its purpose only to serve C/R needs >> (for same sake I wrapped code with CONFIG_CHECKPOINT_RESTORE). >> Still if needed the ioctl may be extended for new commands >> and CONFIG_CHECKPOINT_RESTORE dropped off. Why does this need CAP_SYS_RESOURCE? --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
