From: David Miller <davem@xxxxxxxxxxxxx> Date: Wed, 12 Feb 2014 23:05:06 -0500 (EST) > From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> > Date: Wed, 12 Feb 2014 17:39:02 -0800 > >> Yes, that's horrible as well, but as was already pointed out in this >> thread, you can't rely on that value to really be "1" after reading it >> due to the way krefs work, what happened if someone else just grabbed >> it? >> >> If all they want is a "count" for when to start polling, then use a >> separate atomic count, but don't abuse the kref interface for this, I >> don't think that will work properly at all. > > They want to know which thread of control decrements the count to "1" > as buffers are released. > > That seems entirely reasonable to me. > > They could add another atomic counter for this, but that's rather > silly since the kref already has an atomic they can use for this > purpose. If you still can't understand what they are trying to do, they want to do something precisely when the number of pending buffers is dropped to 1 or less. They are using krefs to track how many buffers are attached at a given moment. The counter can re-increment after the decrement to 1 or less occurs, they don't care. But they want precisely the entity that drops it down to 1 or less to perform that action. Just reading the atomic value directly, they cannot do this. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
