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[2003:dc:6f46:c100:230:64ff:fe74:809]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ad1894c025esm28889966b.114.2025.05.02.03.39.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 May 2025 03:39:08 -0700 (PDT) From: Max Kellermann To: akpm@linux-foundation.org, song@kernel.org, joel.granados@kernel.org, dianders@chromium.org, cminyard@mvista.com, linux-kernel@vger.kernel.org Cc: Max Kellermann Subject: [PATCH 2/2] kernel/rcu/tree_stall: add /sys/kernel/rcu_stall_count Date: Fri, 2 May 2025 12:39:05 +0200 Message-ID: <20250502103905.3995477-2-max.kellermann@ionos.com> X-Mailer: git-send-email 2.47.2 In-Reply-To: <20250502103905.3995477-1-max.kellermann@ionos.com> References: <20250502103905.3995477-1-max.kellermann@ionos.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Exposing a simple counter to userspace for monitoring tools. Signed-off-by: Max Kellermann --- kernel/rcu/tree_stall.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 925fcdad5dea..158330524795 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -20,6 +20,28 @@ int sysctl_panic_on_rcu_stall __read_mostly; int sysctl_max_rcu_stall_to_panic __read_mostly; +#ifdef CONFIG_SYSFS + +static unsigned int rcu_stall_count; + +static ssize_t rcu_stall_count_show(struct kobject *kobj, struct kobj_attribute *attr, + char *page) +{ + return sysfs_emit(page, "%u\n", rcu_stall_count); +} + +static struct kobj_attribute rcu_stall_count_attr = __ATTR_RO(rcu_stall_count); + +static __init int kernel_rcu_stall_sysfs_init(void) +{ + sysfs_add_file_to_group(kernel_kobj, &rcu_stall_count_attr.attr, NULL); + return 0; +} + +late_initcall(kernel_rcu_stall_sysfs_init); + +#endif // CONFIG_SYSFS + #ifdef CONFIG_PROVE_RCU #define RCU_STALL_DELAY_DELTA (5 * HZ) #else @@ -784,6 +806,10 @@ static void check_cpu_stall(struct rcu_data *rdp) if (kvm_check_and_clear_guest_paused()) return; +#ifdef CONFIG_SYSFS + ++rcu_stall_count; +#endif + rcu_stall_notifier_call_chain(RCU_STALL_NOTIFY_NORM, (void *)j - gps); if (READ_ONCE(csd_lock_suppress_rcu_stall) && csd_lock_is_stuck()) { pr_err("INFO: %s detected stall, but suppressed full report due to a stuck CSD-lock.\n", rcu_state.name); -- 2.47.2