Hello, On Fri, Mar 27, 2015 at 01:38:54AM +1100, Aleksa Sarai wrote: > The issue I can see with passing around an opaque pointer to fork() is that you > have a random private (void **) argument that is completely useless if you > don't use can_fork(). This is why I think we should call the reapply_fork() Just pass NULL? I really don't like having another callback. pre and post do make sense because the operation is essentially a transaction. The problem with adding additional callbacks is that they aren't essential and as such arbitrary to a certain degree. reapply_fork or whatnot may fit this case but may not others, so let's please stick with what the logic dictates to be essential. > callback if the association changes [we could call it something else if you > like, since reapply_fork() is a pids-specific name -- what about switch_fork(), > reassoc_fork(), re_fork() or something to show that it's a callback if the > association changes?] (the subsystem can decide if they want to ignore it / if > they don't want to touch it) and we deal with pinning / dropping the ref of the > css_set for the current task inside the cgroup_* callbacks. That way, we don't > start messing around with post-fork() callbacks that aren't related to the new > conditional stuff. You can't pin css_set from inside cgroup callbacks. It's a construct which in general shouldn't be accessible outside cgroup core. > I mean, if you want to have a random, completely unused and essentially > vestigial argument to ss->fork() [if you don't use the new can_fork() callbacks > (and actually care about storing private data)] then I can just write that. It > just looks like a weird callback API imho. It's an opaque token from pre. If a subsys doesn't have pre, it's NULL. I don't see anything weird about that, so let's please go that way. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
