From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-225.mta1.migadu.com [95.215.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F0EB043E071 for ; Mon, 7 Sep 2026 08:14:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.225 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788768897; cv=none; b=nmLJatnJzpMW5n4C0sixPTGN+KfZXVd0d2f0Ef82Kc9yr1Lv78PAOGFmExLci8HlEZBs/OWCSG9arywkY8i8i3dNpAX9nJYcEMK/m3Vq4A5hkFYAnwMNanMEdBCJpx4mQrXFIA5cMLH5x7AfAUBaq7A5RFbRfwvSnNwsOesd3Ks= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788768897; c=relaxed/simple; bh=GYHf+zbpJIbN8wdET2m2KoX50bTFoVYyZ6SIH+UzDwc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=GL+MyXQVz9TbclIE5+dPzOr40XlQ09H2qgpQuONpxC8pXUYHndZyjibHtTe/Ep54hw4SigxHJUr9zoigbcLUVLMjwRi/BiGmgotpPcyag8YI6jNS8YgJAuwTEzPhPCcEOGlYsAtAyKG4Hkd5SyfX5A1z4viUjMr8qS/2IVpHfIg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=MOc/mC2A; arc=none smtp.client-ip=95.215.58.225 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="MOc/mC2A" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=GYHf+zbpJIbN8wdET2m2KoX50bTFoVYyZ6SIH+UzDwc=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788768894; v=1; x=1789373694; b=MOc/mC2AliSYf/QE9dGsNhWvkEEtPI0PpObZW5TPjZIXRl86mLaBVkCw/5QFm6MeG8zIEIzx 1vv4xLl9OqEdXoHS4ctmBuu/Yc/IwBYuOyOkwhg8GCDkJTtZHOT8DDxRsr0g3fdfxdWlYq1hkBd hPKjisOWpKyh1ogG4LIhPEKM= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 70f3f824a87c0db2; Mon, 07 Sep 2026 08:14:52 +0000 X-Mizu-Trace-ID: 70f3f824a87c0db2 X-Migadu-Flow: FLOW_OUT From: Ye Liu To: Thomas Gleixner , Peter Zijlstra , "Rafael J. Wysocki" , Andrew Morton , Ingo Molnar , Will Deacon , Boqun Feng , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Juri Lelli , Vincent Guittot , Steven Rostedt , Masami Hiramatsu , Josh Poimboeuf Cc: Ye Liu , Michal Hocko , mic@digikod.net, oleg@redhat.com, david@kernel.org, linmiaohe@huawei.com, nao.horiguchi@gmail.com, gnoack3000@gmail.com, ljs@kernel.org, sj@kernel.org, rientjes@google.com, shakeel.butt@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, 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, 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 v2 5/8] kernel: convert process/thread iterators to for_each_*_rculock Date: Mon, 7 Sep 2026 16:13:31 +0800 Message-Id: <20260907081334.1152889-6-ye.liu@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260907081334.1152889-1-ye.liu@linux.dev> References: <20260907081334.1152889-1-ye.liu@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Ye Liu Replace the manual rcu_read_lock()/rcu_read_unlock() and guard(rcu) pairs combined with for_each_process(), for_each_thread() and for_each_process_thread() loops across kernel/ with the for_each_*_rculock() macros, which scope the RCU read lock to the loop body via scoped_guard(rcu). No functional change. Signed-off-by: Ye Liu Acked-by: Michal Hocko --- Changes in v2: - Rename *_rcu to *_rculock - Rename stale 'unlock:' label to 'out:' in hung_task.c (Günther Noack) kernel/cpu.c | 4 +--- kernel/freezer.c | 4 +--- kernel/hung_task.c | 11 ++++------- kernel/locking/lockdep.c | 4 +--- kernel/rcu/update.c | 4 +--- kernel/sched/core.c | 3 +-- kernel/sched/debug.c | 4 +--- kernel/trace/fgraph.c | 8 ++------ kernel/unwind/deferred.c | 3 +-- 9 files changed, 13 insertions(+), 32 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index b3c8553d7bd6..00638d2abc0f 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1254,8 +1254,7 @@ void clear_tasks_mm_cpumask(int cpu) * full-fledged tasklist_lock. */ WARN_ON(cpu_online(cpu)); - rcu_read_lock(); - for_each_process(p) { + for_each_process_rculock(p) { struct task_struct *t; /* @@ -1268,7 +1267,6 @@ void clear_tasks_mm_cpumask(int cpu) arch_clear_mm_cpumask_cpu(cpu, t->mm); task_unlock(t); } - rcu_read_unlock(); } /* Take this CPU down. */ diff --git a/kernel/freezer.c b/kernel/freezer.c index a76bf957fb32..7a870f71dcf6 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -217,11 +217,9 @@ void thaw_process(struct task_struct *p) { struct task_struct *t; - rcu_read_lock(); - for_each_thread(p, t) { + for_each_thread_rculock(p, t) { __thaw_task(t); } - rcu_read_unlock(); } /** diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 6fcc94ce4ca9..73a5ad3be9a8 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -315,13 +315,12 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) return; this_round_count = 0; - rcu_read_lock(); - for_each_process_thread(g, t) { + for_each_process_thread_rculock(g, t) { if (!max_count--) - goto unlock; + goto out; if (time_after(jiffies, last_break + HUNG_TASK_LOCK_BREAK)) { if (!rcu_lock_break(g, t)) - goto unlock; + goto out; last_break = jiffies; } @@ -337,9 +336,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) hung_task_info(t, timeout, this_round_count); } } - unlock: - rcu_read_unlock(); - +out: if (!this_round_count) return; diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index c56a7f91d72e..ea218dc75ad5 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -6834,15 +6834,13 @@ void debug_show_all_locks(void) } pr_warn("\nShowing all locks held in the system:\n"); - rcu_read_lock(); - for_each_process_thread(g, p) { + for_each_process_thread_rculock(g, p) { if (!p->lockdep_depth) continue; lockdep_print_held_locks(p); touch_nmi_watchdog(); touch_all_softlockup_watchdogs(); } - rcu_read_unlock(); pr_warn("\n"); pr_warn("=============================================\n\n"); diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 2a778b8ab4ad..d8e0b5896db9 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -548,15 +548,13 @@ void synchronize_rcu_trivial_preempt(void) struct task_struct *t; smp_mb(); // Order prior accesses before grace-period start. - rcu_read_lock(); // Protect task list. - for_each_process_thread(g, t) { + for_each_process_thread_rculock(g, t) { if (t == current) continue; // Don't deadlock on ourselves! // Order later rcu_read_lock() on other tasks after QS. while (smp_load_acquire(&t->rcu_trivial_preempt_nesting)) continue; } - rcu_read_unlock(); } EXPORT_SYMBOL_GPL(synchronize_rcu_trivial_preempt); #endif // #if IS_ENABLED(CONFIG_TRIVIAL_PREEMPT_RCU) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0697ed0f1c3d..fd5bdd2cb798 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2005,8 +2005,7 @@ static void uclamp_sync_util_min_rt_default(void) smp_mb__after_spinlock(); read_unlock(&tasklist_lock); - guard(rcu)(); - for_each_process_thread(g, p) + for_each_process_thread_rculock(g, p) uclamp_update_util_min_rt_default(p); } diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 72236db67983..cdae165b98f7 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -1029,14 +1029,12 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu) #endif "\n"); - rcu_read_lock(); - for_each_process_thread(g, p) { + for_each_process_thread_rculock(g, p) { if (task_cpu(p) != rq_cpu) continue; print_task(m, rq, p); } - rcu_read_unlock(); } void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq) diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 40d373d65f9b..f797ce119223 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -1057,11 +1057,10 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list) } } - rcu_read_lock(); - for_each_process_thread(g, t) { + for_each_process_thread_rculock(g, t) { if (start == end) { ret = -EAGAIN; - goto unlock; + goto free; } if (t->ret_stack == NULL) { @@ -1074,9 +1073,6 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list) t->ret_stack = ret_stack_list[start++]; } } - -unlock: - rcu_read_unlock(); free: for (i = start; i < end; i++) kmem_cache_free(fgraph_stack_cachep, ret_stack_list[i]); diff --git a/kernel/unwind/deferred.c b/kernel/unwind/deferred.c index 5bea47314254..ecfe1336095e 100644 --- a/kernel/unwind/deferred.c +++ b/kernel/unwind/deferred.c @@ -319,9 +319,8 @@ void unwind_deferred_cancel(struct unwind_work *work) synchronize_srcu(&unwind_srcu); - guard(rcu)(); /* Clear this bit from all threads */ - for_each_process_thread(g, t) { + for_each_process_thread_rculock(g, t) { atomic_long_andnot(BIT(bit), &t->unwind_info.unwind_mask); if (t->unwind_info.cache) -- 2.25.1