Re: [PATCH RFC -rcu/dev] hazptrtorture: Release all deferred hazard pointers before stopping

[Bradley Morgan]

On 20 October 2026 19:36:47 BST, "Paul E. McKenney" <paulmck@xxxxxxxxxx>
wrote:
>On Mon, Oct 19, 2026 at 07:32:28PM +0200, Andrea Parri wrote:
>> On Mon, Oct 19, 2026 at 05:22:54PM +0100, Bradley Morgan wrote:
>> > On 19 October 2026 17:20:03 BST, Andrea Parri <parri.andrea@xxxxxxxxx>
>> > wrote:
>> 
>> [...]
>> 
>> > >Fixes: f23d7b47ced9 ("hazptrtorture: Add kthread to release deferred
>hazard pointers")
>> > >Assisted-by: LLM
>> >
>> > Why not put this into a series?
>> 
>> The two patches fix unrelated bugs, touch different files, and apply in
>> either order, so I posted them separately.  But both are for -rcu/dev,
>> and the test notes in the hazptr patch rely on this one.  I'll send the
>> next version as a two-patch series with this patch first, unless Paul
>> prefers separate submissions.
>
>I am fine either way.  But whatever you do, please do *not* put them
>into the same patch.  ;-)
>
>> [...]
>> 
>> > >+	/*
>> > >+	 * Run until hazptr_torture_cleanup() stops this kthread, not just
>> > >+	 * until torture_must_stop(): the writer can be waiting in ->sync()
>> > >+	 * for a deferred hazard pointer while it is being stopped.
>> > >+	 */
>> >
>> > Could this be shorter?
>> 
>> Yes.  The comment in hazptr_torture_cleanup() already says why, so this
>> one can just point there:
>> 
>> 	/* Keep going until hazptr_torture_cleanup() stops us, see there. */
>> 
>> [...]
>
>The longer one is better.
>
>> > >+	/* The readers have stopped, so nothing new can be deferred. */
>> > >+	for_each_possible_cpu(cpu)
>> >
>> > Is the comment needed? I don't know if it's nessesary.
>> 
>> I'd keep it.  A reader can defer after the last pass in the loop, and
>> kthread_stop() can then end the loop without another pass, so this
>> pass is needed; the comment says why one pass is enough.
>> 
>> > >+	/*
>> > >+	 * Stop do_pending only after the writer and the readers: the writer
>> > >+	 * may be waiting on hazard pointers that readers deferred.
>> > >+	 */
>> >
>> > May we shorten this? Feel free to bikeshed that one.
>> 
>> Sure:
>> 
>> 	/* The writer may wait on hazard pointers that readers deferred. */
>
>And same here.
>
>I am sure that it is possible to create shorter versions that keep all
>to the information, but I am OK with Andrea's original versions.
>
>Bradley, Andrea is not a native English speaker and I believe that
>you are, so if you want better wording here, please provide it to him.
>Perhaps someday he will return the favor should you ever be required to
>write in Italian (or German or Ladin, for that matter).  ;-)

Well, or he could be my language teacher :)

Yeah, if those don't need to be accounted for, I'm fine with this :D

Acked-by: Bradley Morgan <brads@xxxxxxxxxxxxxx>

>
>							Thanx, Paul
>
>> Thanks for the review,
>>   Andrea


--- Thanks!
https://lore.kernel.org/all/EE579805-42F2-4C58-B752-F28779EEB717@xxxxxxxxx/