On Fri, Jul 13, 2012 at 10:10:52AM +0100, shan kang wrote: > For example, in the following scenario, Process2 may get the wrong value; > Process1: > mutex_lock(&lock); > write data; (store operation) > mutex_unlock(&lock); > > Process2: > mutex_lock(&lock); > read data; (load operation) > mutex_unlock(&lock);
Yes, it looks like we can screw things up in the uncontended case (where nobody blocks on the mutex). We could add an smp_mb after the lock operation and another one before the unlock, but I'm tempted just to use asm-generic/mutex-dec.h instead. The latter approach will subtly change the current behaviour, so I'll post a patch when I'm happy with it. Curious: did you find this by inspection or did you observe it going wrong? Cheers, Will -- 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/
