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Mon, 19 Oct 2026 10:32:39 -0700 (PDT) Received: from andreayoga.wind3.hub ([151.76.51.95]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e1d823b7esm253426f8f.40.2026.10.19.10.32.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2026 10:32:39 -0700 (PDT) From: Andrea Parri To: Bradley Morgan Cc: Andrea Parri , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Kunwu Chan , rcu@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC -rcu/dev] hazptrtorture: Release all deferred hazard pointers before stopping Date: Mon, 19 Oct 2026 19:32:28 +0200 Message-ID: <20261019173230.73558-1-parri.andrea@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: <20261019162005.12888-1-parri.andrea@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Mon, Oct 19, 2026 at 05:22:54PM +0100, Bradley Morgan wrote: > On 19 October 2026 17:20:03 BST, Andrea Parri > 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. [...] > >+ /* > >+ * 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 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. */ Thanks for the review, Andrea