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Fri, 11 Sep 2026 07:58:35 +0000 X-Mizu-Trace-ID: 7120d82fe4ac0fd4 X-Migadu-Flow: FLOW_OUT From: Ye Liu To: "Peter Zijlstra (Intel)" , Marco Elver , Oleg Nesterov , Ye Liu , Michal Hocko , Bart Van Assche , Christian Brauner Cc: SJ Park , Gregory Price , Lorenzo Stoakes , paulmck@kernel.org, mingo@redhat.com, rostedt@goodmis.org, jpoimboe@kernel.org, mic@digikod.net, tglx@kernel.org, akpm@linux-foundation.org, david@kernel.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com, rafael@kernel.org, gnoack3000@gmail.com, rientjes@google.com, shakeel.butt@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, will@kernel.org, boqun@kernel.org, frederic@kernel.org, neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com, josh@joshtriplett.org, urezki@gmail.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, tony.luck@intel.com, reinette.chatre@intel.com, x86@kernel.org, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, pavel@kernel.org, lance.yang@linux.dev, mhiramat@kernel.org, pmladek@suse.com, longman@redhat.com, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang@linux.dev, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, mark.rutland@arm.com, Dave.Martin@arm.com, james.morse@arm.com, babu.moger@amd.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, rcu@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v3 01/15] sched: introduce for_each_process_rculock and for_each_thread_rculock Date: Fri, 11 Sep 2026 15:57:46 +0800 Message-Id: <20260911075800.491472-2-ye.liu@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260911075800.491472-1-ye.liu@linux.dev> References: <20260911075800.491472-1-ye.liu@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: 6mxo4oxjnc9hjjyhozqrx98eewffb5jh X-Rspamd-Queue-Id: 028B740007 X-HE-Tag: 1789113516-609736 X-HE-Meta: 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 Ne9FFs/D 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ye Liu Introduce for_each_process_rculock(), for_each_thread_rculock() and for_each_process_thread_rculock() macros that acquire the RCU read lock before the iteration starts and release it when the loop is left, so that the RCU read-side critical section is scoped to the loop body instead of an externally managed rcu_read_lock()/rcu_read_unlock() pair. Signed-off-by: Ye Liu Acked-by: Michal Hocko Reviewed-by: SJ Park Reviewed-by: Gregory Price (Meta) Reviewed-by: Oleg Nesterov Reviewed-by: Lorenzo Stoakes (ARM) --- Changes in v3: - Indent loop body to show scoped_guard scope (Lorenzo Stoakes) Changes in v2: - Rename macros from *_rcu to *_rculock (Steven Rostedt, Thomas Gleixner) - Improve comment on for_each_process_thread_rculock() double loop - Change prefix from mm: to sched: (Michal Hocko) include/linux/sched/signal.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index 584ae88b435e..ea23c7e9db33 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -2,6 +2,7 @@ #ifndef _LINUX_SCHED_SIGNAL_H #define _LINUX_SCHED_SIGNAL_H +#include #include #include #include @@ -663,6 +664,31 @@ extern bool current_is_single_threaded(void); #define for_each_process_thread(p, t) \ for_each_process(p) for_each_thread(p, t) +/* + * Variants of for_each_process(), for_each_thread() and + * for_each_process_thread() that automatically acquire and release the + * RCU read lock via scoped_guard(rcu). The lock is held for the + * duration of the loop and released on exit, including via break, + * goto, or return. + */ +#define for_each_process_rculock(p) \ + scoped_guard(rcu) \ + for (p = &init_task ; (p = next_task(p)) != &init_task ; ) + +#define for_each_thread_rculock(p, t) \ + scoped_guard(rcu) \ + __for_each_thread((p)->signal, t) + +/* + * Double loop: 'break' only exits the inner for_each_thread() loop. + * Use 'goto' to exit both loops; the RCU read lock is released + * automatically when the scoped_guard scope is left. + */ +#define for_each_process_thread_rculock(p, t) \ + scoped_guard(rcu) \ + for_each_process(p) \ + for_each_thread(p, t) + typedef int (*proc_visitor)(struct task_struct *p, void *data); void walk_process_tree(struct task_struct *top, proc_visitor, void *); -- 2.25.1