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Thu, 10 Sep 2026 01:46:38 -0700 (PDT) From: Kunwu Chan To: paulmck@kernel.org, jiangshanlai@gmail.com, josh@joshtriplett.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, Kunwu Chan Subject: [PATCH v2] srcutree: Add WARN_ON_ONCE() for atomic SRCU in srcu_gp_end() Date: Thu, 10 Sep 2026 16:46:29 +0800 Message-ID: <20260910084629.3695383-1-kunwu.chan@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Atomic SRCU remain in the small size state, so add a WARN_ON_ONCE() before the transition check to catch any future code path that might violate this invariant. Signed-off-by: Kunwu Chan --- Changes since v1: - Drop the !is_atomic guard from v1 and add WARN_ON_ONCE() instead, per Paul McKenney's suggestion. - v1: https://lore.kernel.org/rcu/20260907075829.2073224-8-kunwu.chan@linux.dev/ --- kernel/rcu/srcutree.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 84c022ec8e09..68441c32cebf 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1074,6 +1074,8 @@ static void srcu_gp_end(struct srcu_struct *ssp, bool is_atomic) } /* Transition to big if needed. */ + WARN_ON_ONCE(ssp->srcu_reader_flavor == SRCU_READ_FLAVOR_ATOMIC && + ss_state != SRCU_SIZE_SMALL); if (ss_state != SRCU_SIZE_SMALL && ss_state != SRCU_SIZE_BIG) { if (ss_state == SRCU_SIZE_ALLOC) init_srcu_struct_nodes(ssp, GFP_KERNEL); -- 2.43.0