From patchwork Tue Nov 28 08:00:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Uladzislau Rezki X-Patchwork-Id: 13470586 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="W/PgcouF" Received: from mail-lf1-x12f.google.com (mail-lf1-x12f.google.com [IPv6:2a00:1450:4864:20::12f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3883BCB; Tue, 28 Nov 2023 00:00:44 -0800 (PST) Received: by mail-lf1-x12f.google.com with SMTP id 2adb3069b0e04-50abb83866bso6933036e87.3; Tue, 28 Nov 2023 00:00:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701158442; x=1701763242; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=QQVOvwrmfo1nPfUgIyQbOVsMWsIZrJImgM152q/sqUE=; b=W/PgcouFN/Z8pHWi5vDSGdOT1N5xbMMpc+cYROJFFgVtTK/TtpHatoK3A8HuGvSaSz UHiZCaRUUKegN4wsUoFPGtYo7xXlKolFOtJc0BoQ01aLah0HZCeEyO0Vp+jCcnv8k1Df vwOGTSMTVJjEDS8dz8N90ovwdbMdqHckOJnAIeQKjiQzLLJmbfMzPXvVo9tNWAiHY9qr ryHVY277Dg7evEmo1KConVX6ew7bmAAezkeG7EGxIDSLtJH4tgA5v5G8KHimunS/wyij b0nkPB7WsPFZT+nobrcficgZ/rwcWm7NX+RAqyhzJStnotTOMKS97OT1d/Np9tLafqEZ U6IQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701158442; x=1701763242; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=QQVOvwrmfo1nPfUgIyQbOVsMWsIZrJImgM152q/sqUE=; b=Et/VHFtJzCerm5EgrTn05ATQ5LOHhiXd33ql4/YyvleEn2Tbmypp3+mIizrGXdKZLn +SQY1WoEAUvt/wGiRwJ7a0oAK5AVssHkU0mImXDsmmJZILhTTYIv6ms7JWBhFK1uzQt6 MwgV/+o5G7Q3gERQS54EOV9r2CadaRvZOthBTVpN8fnWtE6vhxsnqke+hO/XMXwnh7Sf OlfukZ01N7kJ/B+IEEjTzJZxVPLoPyCFvmYtBgHOLtor9NiSHDGebe8aFaEMuOzkBDT8 TN4sQncb69IOUCGRYrsV0gDpeCTFW8XiUNJv+7OgiPkMKjo+6coo/TN597oPe9YHcYva AQNw== X-Gm-Message-State: AOJu0Yx0KlAT1C4TKMZSGsOn9kLTw+reYOHT9RqOE3wu4/2DxliT0tPC nu7QHy2lFZMf/+U0CaisV7s= X-Google-Smtp-Source: AGHT+IGpGnDLULRUYULHIiEqENx6drVMGcTjDMRTQ69MqVN/chnP9zQSnV1eWsGowYbRCIcIp5MNkQ== X-Received: by 2002:a19:5506:0:b0:500:b53f:fbc2 with SMTP id n6-20020a195506000000b00500b53ffbc2mr8986246lfe.26.1701158442372; Tue, 28 Nov 2023 00:00:42 -0800 (PST) Received: from pc638.lan ([155.137.26.201]) by smtp.gmail.com with ESMTPSA id o16-20020ac24bd0000000b004fe202a5c7csm1765501lfq.135.2023.11.28.00.00.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Nov 2023 00:00:42 -0800 (PST) From: "Uladzislau Rezki (Sony)" To: "Paul E . McKenney" Cc: RCU , Neeraj upadhyay , Boqun Feng , Hillf Danton , Joel Fernandes , LKML , Uladzislau Rezki , Oleksiy Avramchenko , Frederic Weisbecker Subject: [PATCH v3 7/7] rcu: Add CONFIG_RCU_SR_NORMAL_DEBUG_GP Date: Tue, 28 Nov 2023 09:00:33 +0100 Message-Id: <20231128080033.288050-8-urezki@gmail.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231128080033.288050-1-urezki@gmail.com> References: <20231128080033.288050-1-urezki@gmail.com> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This option enables additional debugging for detecting a grace period incompletion for synchronize_rcu() users. If a GP is not fully passed for any user, the warning message is emitted. Signed-off-by: Uladzislau Rezki (Sony) --- kernel/rcu/Kconfig.debug | 12 ++++++++++++ kernel/rcu/tree.c | 7 +++++-- 2 files changed, 17 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug index 2984de629f74..3d44106ca1f0 100644 --- a/kernel/rcu/Kconfig.debug +++ b/kernel/rcu/Kconfig.debug @@ -143,4 +143,16 @@ config RCU_STRICT_GRACE_PERIOD when looking for certain types of RCU usage bugs, for example, too-short RCU read-side critical sections. +config RCU_SR_NORMAL_DEBUG_GP + bool "Debug synchronize_rcu() callers for a grace period completion" + depends on DEBUG_KERNEL && RCU_EXPERT + default n + help + This option enables additional debugging for detecting a grace + period incompletion for synchronize_rcu() users. If a GP is not + fully passed for any user, the warning message is emitted. + + Say Y here if you want to enable such debugging + Say N if you are unsure. + endmenu # "RCU Debugging" diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index c0d3e46730e8..421bce4b8dd7 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1547,7 +1547,8 @@ static void rcu_sr_normal_complete(struct llist_node *node) (struct rcu_head *) node, struct rcu_synchronize, head); unsigned long oldstate = (unsigned long) rs->head.func; - WARN_ONCE(!rcu_gp_is_expedited() && !poll_state_synchronize_rcu(oldstate), + WARN_ONCE(IS_ENABLED(CONFIG_RCU_SR_NORMAL_DEBUG_GP) && + !poll_state_synchronize_rcu(oldstate), "A full grace period is not passed yet: %lu", rcu_seq_diff(get_state_synchronize_rcu(), oldstate)); @@ -3822,7 +3823,9 @@ static void synchronize_rcu_normal(void) * This code might be preempted, therefore take a GP * snapshot before adding a request. */ - rs.head.func = (void *) get_state_synchronize_rcu(); + if (IS_ENABLED(CONFIG_RCU_SR_NORMAL_DEBUG_GP)) + rs.head.func = (void *) get_state_synchronize_rcu(); + rcu_sr_normal_add_req(&rs); /* Kick a GP and start waiting. */