On Thu, 2014-08-14 at 16:16 +1000, Benjamin Herrenschmidt wrote: > Another interesting one in the "OMG" category is the series from Michael > adding memory barriers to spin_is_locked(). That's also the result of many > days of debugging to figure out why the semaphore code would occasionally > crash in ways that made no sense. It ended up being some creative lock > stacking that was defeated by the fact that our locks allow a load inside > the locked section to be re-ordered with the load of the lock value itself > (I'm still of two mind about whether to kill that once and for all by putting > a heavier barrier back into our lock implementation...). The fixes come with > a long explanation in the cset comments, feel free to read it if you feel > like having a headache today.
Talking of which, I should have tagged that for stable... I'll forward them separately when you've pulled. Michael: If I miss this while I'm away next week, can you take care of it ? Cheers, Ben. -- 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/
