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[109.81.91.122]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49cee7febb4sm157781205e9.14.2026.09.04.04.09.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Sep 2026 04:09:38 -0700 (PDT) Date: Fri, 4 Sep 2026 13:09:35 +0200 From: Michal Hocko To: Ye Liu Cc: Andrew Morton , Ye Liu , linux-kernel@vger.kernel.org Subject: Re: [PATCH 7/8] lib: convert process iterator to for_each_process_rcu Message-ID: References: <20260904083001.553587-1-ye.liu@linux.dev> <20260904083001.553587-8-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=us-ascii Content-Disposition: inline In-Reply-To: <20260904083001.553587-8-ye.liu@linux.dev> On Fri 04-09-26 16:29:59, Ye Liu wrote: > From: Ye Liu > > Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined > with for_each_process() loop in lib/ with for_each_process_rcu(). > > No functional change. > > Signed-off-by: Ye Liu > --- > lib/is_single_threaded.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/lib/is_single_threaded.c b/lib/is_single_threaded.c > index 8c98b20bfc41..0682dc87bcdf 100644 > --- a/lib/is_single_threaded.c > +++ b/lib/is_single_threaded.c > @@ -26,8 +26,7 @@ bool current_is_single_threaded(void) > return true; > > ret = false; > - rcu_read_lock(); > - for_each_process(p) { > + for_each_process_rcu(p) { > if (unlikely(p->flags & PF_KTHREAD)) > continue; > if (unlikely(p == task->group_leader)) > @@ -48,7 +47,5 @@ bool current_is_single_threaded(void) > } > ret = true; > found: > - rcu_read_unlock(); > - > return ret; This can be slightly simplified as below. Anyway Acked-by: Michal Hocko --- diff --git a/lib/is_single_threaded.c b/lib/is_single_threaded.c index 8c98b20bfc41..4f7620481066 100644 --- a/lib/is_single_threaded.c +++ b/lib/is_single_threaded.c @@ -17,7 +17,6 @@ bool current_is_single_threaded(void) struct task_struct *task = current; struct mm_struct *mm = task->mm; struct task_struct *p, *t; - bool ret; if (atomic_read(&task->signal->live) != 1) return false; @@ -25,9 +24,7 @@ bool current_is_single_threaded(void) if (atomic_read(&mm->mm_users) == 1) return true; - ret = false; - rcu_read_lock(); - for_each_process(p) { + for_each_process_rcu(p) { if (unlikely(p->flags & PF_KTHREAD)) continue; if (unlikely(p == task->group_leader)) @@ -35,7 +32,7 @@ bool current_is_single_threaded(void) for_each_thread(p, t) { if (unlikely(t->mm == mm)) - goto found; + return false if (likely(t->mm)) break; /* @@ -46,9 +43,5 @@ bool current_is_single_threaded(void) smp_rmb(); } } - ret = true; -found: - rcu_read_unlock(); - - return ret; + return true; } -- Michal Hocko SUSE Labs