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Mon, 07 Sep 2026 00:59:19 -0700 (PDT) From: Kunwu Chan X-Google-Original-From: Kunwu Chan To: paulmck@kernel.org, jiangshanlai@gmail.com, josh@joshtriplett.org Cc: rostedt@goodmis.org, mathieu.desnoyers@efficios.com, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, Kunwu Chan Subject: [PATCH 10/13] srcutree: Skip callback scheduling for atomic SRCU grace periods Date: Mon, 7 Sep 2026 15:58:26 +0800 Message-ID: <20260907075829.2073224-11-kunwu.chan@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260907075829.2073224-1-kunwu.chan@linux.dev> References: <20260907075829.2073224-1-kunwu.chan@linux.dev> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Kunwu Chan call_srcu() is forbidden on atomic srcu_struct, so srcu_gp_end() never has callbacks to invoke for them. Yet it schedules callback invocation, which for atomic SRCU's SRCU_SIZE_SMALL state arms the boot CPU's ->delay_work timer every grace period, only for srcu_invoke_callbacks() to find nothing to do. Skip this for atomic SRCU. Signed-off-by: Kunwu Chan --- kernel/rcu/srcutree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 2d2a12f86115..c19f59725706 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1018,10 +1018,10 @@ static void srcu_gp_end(struct srcu_struct *ssp, bool is_atomic) /* Initiate callback invocation as needed. */ ss_state = smp_load_acquire(&sup->srcu_size_state); - if (ss_state < SRCU_SIZE_WAIT_BARRIER) { + if (!is_atomic && ss_state < SRCU_SIZE_WAIT_BARRIER) { srcu_schedule_cbs_sdp(per_cpu_ptr(ssp->sda, get_boot_cpu_id()), cbdelay); - } else { + } else if (!is_atomic) { idx = rcu_seq_ctr(gpseq) % ARRAY_SIZE(snp->srcu_have_cbs); srcu_for_each_node_breadth_first(ssp, snp) { raw_spin_lock_irq_rcu_node(snp); -- 2.43.0