On Wed, 6 Jun 2007, Benjamin Herrenschmidt wrote: > On Tue, 2007-06-05 at 17:58 -0700, Nicholas Miell wrote: > > > > "At the time of generation, a determination shall be made whether the > > signal has been generated for the process or for a specific thread > > within the process. Signals which are generated by some action > > attributable to a particular thread, such as a hardware fault, shall > > be generated for the thread that caused the signal to be generated. > > Yeah, synchronous signals should probably never be delivered to another > process, even via signalfd. There's no point delivering a SEGV to > somebody else :-)
That'd be a limitation. Like you can choose to not handle SEGV, you can choose to have a signalfd listening to it. Of course, not with the intention to *handle* the signal, but with a notification intent. > I'm actually thinking we shoud -also- only handle shared signals in > dequeue_signal() when called from a different task. Why do you want to impose this? signalfd is a "sniffer", and the user controls what it can dequeue/sniff or what not. I don't see a reason of imposing such limits, unless there're clear technical issues. > > dequeue_signal(tsk, ...) looks for signals first in tsk->pending and > > then in tsk->signal->shared_pending. > > > > sys_signalfd() stores current in signalfd_ctx. signalfd_read() passes > > that context to signalfd_dequeue, which passes that that saved > > task_struct pointer to dequeue_signal. > > > > This means that a signalfd will deliver signals targeted towards > > either the original thread that created that signalfd, or signals > > targeted towards the process as a whole. > > > > This means that a single signalfd is not adequate to handle signal > > delivery for all threads in a process, because signals targeted > > towards threads other than the thread that originally created the > > signalfd will never be queued to that signalfd. > > Well.. you certainly need to instanciate a signalfd for every thread in > the process if you want to get shared signals for sure. Why? Or better, what do you mean for "instanciate"? - Davide - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
