On 12/27/2014 04:52 AM, Davidlohr Bueso wrote: >> Hello， >> > Does ACCESS_ONCE() can help this issue? I have no evidence that its lack is >> > responsible for the issue, but I think here need it indeed. Is that right? >> > >> > SPIN_BUG_ON(ACCESS_ONCE(lock->owner) == current, "recursion"); > Hmm I guess on a contended spinlock, there's a chance that lock->owner > can change, if the contended lock is acquired, right between the 'cond' > and spin_debug(), which would explain the bogus ->owner related > messages. Of course the same applies to ->owner_cpu. Your ACCESS_ONCE, > however, doesn't really change anything since we still read ->owner > again in spin_debug; How about something like this (untested)?
There's a chance that lock->owner would change, but how would you explain it changing to 'current'? That is, what race condition specifically creates the 'lock->owner == current' situation in the debug check? Thanks, Sasha -- 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/
