On Mon, Sep 07, 2026 at 04:13:31PM +0800, Ye Liu wrote: > From: Ye Liu <[email protected]> > > 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 <[email protected]> > Acked-by: Michal Hocko <[email protected]>
LGTM so: Reviewed-by: Lorenzo Stoakes (ARM) <[email protected]> > --- > 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 > -- Cheers, Lorenzo
