On Thu, Feb 23, 2023 at 07:57:13AM -0700, Jens Axboe wrote: > On 2/1/23 8:08 AM, Uladzislau Rezki (Sony) wrote: > > This small series is based on Paul's "dev" branch. Head is 6002817348a1c610dc1b1c01ff81654cdec12be4 > > it renames a single argument of k[v]free_rcu() to its new k[v]free_rcu_mightsleep() name. > > > > 1. > > The problem is that, recently we have run into a precedent when > > a user intended to give a second argument to kfree_rcu() API but > > forgot to do it in a code so a call became as a single argument > > of kfree_rcu() API. > > > > 2. > > Such mistyping can lead to hidden bags where sleeping is forbidden. > > > > 3. > > _mightsleep() prefix gives much more information for which contexts > > it can be used for. > > This patchset seems weird to me. We have a LOT of calls that might > sleep, yet we don't suffix them all with _mightsleep(). Why is this > any different? Why isn't this just a might_sleep() call in the > actual helper, which will suffice for checkers and catch it at > runtime as well. Fair enough, and the situation that this patchset is addressing is also a bit unusual. This change was requested by Eric Dumazet due to a situation where someone forgot the optional second argument to kfree_rcu(). Now, you are right that this would be caught if invoked from a non-sleepable context, but there are also cases where sleeping is legal, but where the occasional wait for an RCU grace period would be a problem. The checkers cannot easily catch this sort of thing, and hence the change in name. Hey, the combined one/two-argument form seemed like a good idea at the time! ;-) Thanx, Paul
