lkml.org 
[lkml]   [2023]   [Feb]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 00/13] Rename k[v]free_rcu() single argument to k[v]free_rcu_mightsleep()
    On Thu, Feb 23, 2023 at 12:36:57PM -0700, Jens Axboe wrote:
    > 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!

    If I remember, would you like me to send you some? ;-)

    Thanx, Paul

    \
     
     \ /
      Last update: 2023-03-27 00:34    [W:2.493 / U:0.068 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site