Re: [PATCH v2] wireguard: queueing: simplify wg_cpumask_next_online()
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: 2025-06-30 17:25:00
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On Thu, Jun 19, 2025 at 10:54:59AM -0400, Yury Norov wrote:
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From: Yury Norov [NVIDIA] <yury.norov@gmail.com> wg_cpumask_choose_online() opencodes cpumask_nth(). Use it and make the function significantly simpler. While there, fix opencoded cpu_online() too. Signed-off-by: Yury Norov [NVIDIA] <yury.norov@gmail.com> --- v1: https://lore.kernel.org/all/20250604233656.41896-1-yury.norov@gmail.com/ (local) v2: - fix 'cpu' undeclared; - change subject (Jason); - keep the original function structure (Jason); drivers/net/wireguard/queueing.h | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-)diff --git a/drivers/net/wireguard/queueing.h b/drivers/net/wireguard/queueing.h index 7eb76724b3ed..56314f98b6ba 100644 --- a/drivers/net/wireguard/queueing.h +++ b/drivers/net/wireguard/queueing.h@@ -104,16 +104,11 @@ static inline void wg_reset_packet(struct sk_buff *skb, bool encapsulating) static inline int wg_cpumask_choose_online(int *stored_cpu, unsigned int id) { - unsigned int cpu = *stored_cpu, cpu_index, i; + unsigned int cpu = *stored_cpu; + + if (unlikely(cpu >= nr_cpu_ids || !cpu_online(cpu))) + cpu = *stored_cpu = cpumask_nth(id % num_online_cpus(), cpu_online_mask);
I was about to apply this but then it occurred to me: what happens if cpu_online_mask changes (shrinks) after num_online_cpus() is evaluated? cpumask_nth() will then return nr_cpu_ids? Jason