Hello, On Thu, Jul 14, 2016 at 01:13:24PM -0400, Waiman Long wrote: > On 07/14/2016 07:50 AM, Tejun Heo wrote: > I got comment related to the percpu-list name from Christoph Lameter a while > ago. His argument was that since deletion can happenned from any CPU, it was > not really percpu like the other percpu structures. That prompted me to > change the name to the current form. I am fine with either names, but I > would like to keep the current name unless there is a great rationale for > switching back. Yeah, I don't know. It's probably gonna stick out as a percpu data structure with a weird name. No biggies. If it actually matters, we can rename it later. Christoph, what do you think? Do you still think dlist is a better name? > > I don't think it makes sense to worry about the cases where the next > > entry to iterate may be removed by the iterator. What I'm trying to > > say is just make the iteration always safe and don't worry about the > > distinction. For list_for_each_entry(), it makes the difference of > > requiring and not requiring a separtae state variable. Here, we need > > it anyway. > > A lot of those functions that need to iterate the list will release the lock > in the middle, do some stuff, reacquire the lock and move on to the next > entry. So it is entirely possible that new entries will be inserted between > the current entry and the next one in between the release and re-acquisition > of the lock. Using the safe version will skip those newly added entries > which is a change in behavior for the current code. That is my main concern > for making it deletion safe by default. I see. The distinction between unsafe and safe versions is pretty subtle. :( > I don't think it is normal to have concurrent deletion of the same entry. > Most likely it is a bug if this happens. Having the warning message in the > kernel log will help to catch those errors. Yeah, maybe. I was thinking more in line of list_del_init(). dlist having its own locking embedded makes it a bit murky which parts of synchronization belong where. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
