Hello, The semaphore API provides several flavors of the down primitive:
down, down_interruptible, down_killable, down_trylock, down_timeout As far as I can tell, they all call __down_common (except down_trylock, which returns 1 where the others would sleep). I was looking for a version 1) with a timeout 2) that could be interrupted e.g. down_interruptible_timeout, but it doesn't exist. It seems __down_common(sem, TASK_INTERRUPTIBLE, timeout); would work as expected, no? Do you know why it is not offered? (Maybe there is a better way to achieve the same thing?) [POST SCRIPTUM EDIT] I found this 2007 discussion: http://thread.gmane.org/gmane.linux.kernel/498034 At the time, Andrew said "Nobody else has needed to invent new locking infrastructure to do such things and I'd prefer not to do so now." I suppose this is still true :-) [/EDIT] My use-case is pretty simple: A) process-context kernel thread fills a FIFO and calls down(&fifo_empty); B) ISR handles the FIFO-empty interrupt with up(&fifo_empty); However, in case something goes wrong and the interrupt never fires, I don't want the process to be stuck in an uninterruptible sleep. Perhaps I can set a tiny timeout (e.g. 10 µs) and not worry about the interruptible part for such a small duration? (Hmm, __down_common calls schedule_timeout, which is jiffies-based. I don't think there is a hrtimers flavor. So µs timeouts would be off the table?) Or I could use the interruptible version, and let the user kill the operation if necessary. I'd like to hear your comments and suggestions. Regards. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/