On 2/23/23 11:31 AM, Paul E. McKenney wrote: > 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! ;-) Hah, not sure what you were smoking back then! -- Jens Axboe
