From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com,
rostedt@goodmis.org, Kunwu Chan <kunwu.chan@gmail.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
Bradley Morgan <brads@mainlining.org>
Subject: [PATCH v2 17/21] srcutree: Don't transition atomic SRCU to big in srcu_gp_end()
Date: Wed, 7 Oct 2026 13:59:20 -0700 [thread overview]
Message-ID: <20261007205924.1983367-17-paulmck@kernel.org> (raw)
In-Reply-To: <546c81a7-f677-4d8e-a304-746b227058b0@paulmck-laptop>
From: Kunwu Chan <kunwu.chan@gmail.com>
Atomic SRCU must remain in the small size state. Warn if this
invariant is violated and avoid transitioning to big in that case.
[ paulmck: Folded "if" onto one line for 100-character limit. ]
Signed-off-by: Kunwu Chan <kunwu.chan@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Bradley Morgan <brads@mainlining.org>
---
kernel/rcu/srcutree.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 4e9a0b8ea3449..6a05bd8a6f390 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -1073,8 +1073,10 @@ static void srcu_gp_end(struct srcu_struct *ssp, bool is_atomic)
raw_spin_unlock_irq_rcu_node(sup);
}
- /* Transition to big if needed. */
- if (ss_state != SRCU_SIZE_SMALL && ss_state != SRCU_SIZE_BIG) {
+ /* Transition to big if needed, but never for atomic SRCU. */
+ if (ssp->srcu_reader_flavor == SRCU_READ_FLAVOR_ATOMIC && ss_state != SRCU_SIZE_SMALL) {
+ WARN_ON_ONCE(1);
+ } else if (ss_state != SRCU_SIZE_SMALL && ss_state != SRCU_SIZE_BIG) {
if (ss_state == SRCU_SIZE_ALLOC)
init_srcu_struct_nodes(ssp, GFP_KERNEL);
else
--
2.40.1
next prev parent reply other threads:[~2026-10-07 20:59 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-07 20:59 [PATCH v2 0/21] Add atomic SRCU &c for v7.4 Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 01/21] srcutiny: Make a Tiny SRCU grace period imply an RCU grace period Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 02/21] srcutree: Suppress srcu_advance_state() mutex_lock in atomic Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 03/21] srcutree: Suppress to-big transition for atomic SRCU Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 04/21] srcutree: Add an atomic Tree SRCU Paul E. McKenney
2026-10-08 7:39 ` David Woodhouse
2026-10-07 20:59 ` [PATCH v2 05/21] srcutiny: Add an atomic Tiny SRCU Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 06/21] rcutorture: Add support for testing synchronize_srcu_atomic() Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 07/21] srcutree: Disable preemption across synchronize_srcu_atomic() Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 08/21] srcu: Use IRQ_WORK_INIT_HARD for srcu's irq_work Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 09/21] srcutree: Warn if Tiny SRCU readers are preempted Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 10/21] srcutree: Explicitly note DEFINE_SRCU() needs for srcu_barrier() Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 11/21] rcutorture: Add atomic-SRCU support to torture.sh Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 12/21] srcutree: Add reader-free fastpath to synchronize_srcu_atomic() Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 13/21] srcutree: Skip callback scheduling for atomic SRCU grace periods Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 14/21] srcutree: Remove srcu_barrier() sleep for atomic SRCU Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 15/21] srcu: Restrict atomic-SRCU non_block annotation to task context Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 16/21] srcutree: Make init_srcu_struct_atomic() prevent transition to big Paul E. McKenney
2026-10-07 20:59 ` Paul E. McKenney [this message]
2026-10-07 20:59 ` [PATCH v2 18/21] srcutree: Skip torture to-big transition for atomic SRCU Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 19/21] srcutree: Add lockdep and early-boot checks to synchronize_srcu_atomic() Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 20/21] srcutiny: " Paul E. McKenney
2026-10-07 20:59 ` [PATCH v2 21/21] srcutree: Preserve IRQ state in synchronize_srcu_atomic() callchain Paul E. McKenney
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