From patchwork Mon Jul 1 20:56:39 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuan-Wei Chiu X-Patchwork-Id: 13718638 X-Patchwork-Delegate: rjw@sisk.pl Received: from mail-pl1-f178.google.com (mail-pl1-f178.google.com [209.85.214.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9EFF9152179; Mon, 1 Jul 2024 20:56:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719867409; cv=none; b=n6wbxJf9cGqHhAHwsXm6jFjv1EO6IZuO7JqiXXuGMEZrAtdoYZPeHzIftZHS+5IRu8ttXqe6F9PDn4eCG85ohj77DltB0pmjurbEdvBlsNSQLrgPHjHnObtYHsZi6I4liKYa6JJZNfMThNFzuUgu64BQRWWkfpWuTeFMaoL8z9I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719867409; c=relaxed/simple; bh=yivC1wh3WXB0Mkllna8y0JKmSTpJlJbqbl1AdYH3amQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=F0iWLOH4OpKfnvdrTyou03+9eFLXDIl9AbaR2w+2juDq+y7NpHMlKKqCoxF/9DkJXrVZaPegwU4oZKfspuxvHK07Ogfvp2/3djneHrl2G0YmpdsDEbm94OPwMpWccEqM0h07O8lkkHrWvBKzDROI5moqa3K1H2fakDjfYyWfv18= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Tr7LeHmk; arc=none smtp.client-ip=209.85.214.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Tr7LeHmk" Received: by mail-pl1-f178.google.com with SMTP id d9443c01a7336-1f99e2dc8cdso2216875ad.0; Mon, 01 Jul 2024 13:56:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1719867407; x=1720472207; 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=tOUox0A8P7WdAUwxhtPV8qdrltE7pejNVtILSbSQpN4=; b=Tr7LeHmkZ82U7MMBhSOKoNBbF4p/ILq32h2Otp0pQXrbIRUvQZjiNRbTFP+ZR7ZYG8 nbal/ZKIiUkNTd3MeParMNjkKCh2iL0NamHB7YSxghIjaGieqHun8DPYhi8gC7XWOhHB 3Z/6a9aOCg5BRMA0ejHTX5QEoGNRtaTlzv6X0fD3waxmDQE2R31wAaEImInc5mwXSRUD 2zG/dPswYJxGWWcbTGqeufxJvvtKnhPV4YfGw4uAU9oT5DL1iY/R1b16FtqCPyQn+8xK eVcGHO1B8KJcfiPj3JvcobU7dzcp7M8zjsKLv2SfB6BjzJjxkHfkP1Kn2M8pTQI6gfVk 6BZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719867407; x=1720472207; 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=tOUox0A8P7WdAUwxhtPV8qdrltE7pejNVtILSbSQpN4=; b=ebKuRXik2GXU3WTEn4UKY1TTDfei7KVayxxxXEaunDlup1ZOxDNg6w2ZRdx3Jwj4Mg xV9tZ5eLZ/sBzGbIueR0+5iwuIkcIQUY53Qqs8vbp5ga0ubIEAUSQC3sWshzX3CpdwIS cwpVHcsPTnsfCD7R0mpNO7YbGzJskOOxuw39p3PysbXlfE4ex3dxj8JAPZXrpOeTFx0Y dNmzgvnVK4ncR6nZSYKmEYHgAJf+np3EHhkpkAzy26hIPn6aI4f66O617yl6cz2mlg8o sI918DzEjbK58sqyae5HCYdIOsFZi1IBmcm8c/fqjxEUYzRrGROWy0288T86Wdy2/YjY /hSA== X-Forwarded-Encrypted: i=1; AJvYcCWISLuNI9QZXVV5THTJIRy7CqJUZzKHz7t6fjGzerUEER8+0VwxeFGfSm8PwRXohw7GodPAs7sjPjo3t8sYgXg/i+MOAUOUCpXa7tImW20kyAywTykh9z74n6b7ejg7iBJs3nzEl+9/XIJDoBw7OQT2SKwL8G6YJQbmAROXCd8fVg== X-Gm-Message-State: AOJu0YyBbEidqzZRoISkDjEwzQU87/HfYHZj1MJ5C+bXIPHFd8zvFHFG t3E5l3toG/mZ+4fQck3Igm+V9dtsviIjWsrenWscS166vW0Krzqx X-Google-Smtp-Source: AGHT+IFrTruC3H2GBbF3mUj3lqAiD5H9fk9Ju69ci44bdKZ4SKOiR//a/zscmxKXvRePm7RkETeIMg== X-Received: by 2002:a05:6a20:7286:b0:1be:d897:797a with SMTP id adf61e73a8af0-1bef626edbdmr9916444637.5.1719867406736; Mon, 01 Jul 2024 13:56:46 -0700 (PDT) Received: from visitorckw-System-Product-Name.. ([140.113.216.168]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fac15393d1sm69402285ad.157.2024.07.01.13.56.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Jul 2024 13:56:46 -0700 (PDT) From: Kuan-Wei Chiu To: rafael@kernel.org Cc: lenb@kernel.org, mario.limonciello@amd.com, akpm@linux-foundation.org, jserv@ccns.ncku.edu.tw, alexdeucher@gmail.com, belegdol@gmail.com, regressions@leemhuis.info, linux-acpi@vger.kernel.org, regressions@lists.linux.dev, linux-kernel@vger.kernel.org, Kuan-Wei Chiu , stable@vger.kernel.org Subject: [PATCH v4] ACPI: processor_idle: Fix invalid comparison with insertion sort for latency Date: Tue, 2 Jul 2024 04:56:39 +0800 Message-Id: <20240701205639.117194-1-visitorckw@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The acpi_cst_latency_cmp comparison function currently used for sorting C-state latencies does not satisfy transitivity, causing incorrect sorting results. Specifically, if there are two valid acpi_processor_cx elements A and B and one invalid element C, it may occur that A < B, A = C, and B = C. Sorting algorithms assume that if A < B and A = C, then C < B, leading to incorrect ordering. Given the small size of the array (<=8), we replace the library sort function with a simple insertion sort that properly ignores invalid elements and sorts valid ones based on latency. This change ensures correct ordering of the C-state latencies. Fixes: 65ea8f2c6e23 ("ACPI: processor idle: Fix up C-state latency if not ordered") Cc: stable@vger.kernel.org Reported-by: Julian Sikorski Closes: https://lore.kernel.org/lkml/70674dc7-5586-4183-8953-8095567e73df@gmail.com/ Signed-off-by: Kuan-Wei Chiu Tested-by: Julian Sikorski --- v3 -> v4: - Rename the parameter 'arr' to 'states'. - Add empty lines to enhance readability. Note: I only performed a build test and a simple unit test to ensure the latency of valid elements is correctly sorted in the randomly generated data. drivers/acpi/processor_idle.c | 37 +++++++++++++++-------------------- 1 file changed, 16 insertions(+), 21 deletions(-) diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index bd6a7857ce05..831fa4a12159 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -16,7 +16,6 @@ #include #include #include /* need_resched() */ -#include #include #include #include @@ -386,25 +385,24 @@ static void acpi_processor_power_verify_c3(struct acpi_processor *pr, acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_RLD, 1); } -static int acpi_cst_latency_cmp(const void *a, const void *b) +static void acpi_cst_latency_sort(struct acpi_processor_cx *states, size_t length) { - const struct acpi_processor_cx *x = a, *y = b; + int i, j, k; - if (!(x->valid && y->valid)) - return 0; - if (x->latency > y->latency) - return 1; - if (x->latency < y->latency) - return -1; - return 0; -} -static void acpi_cst_latency_swap(void *a, void *b, int n) -{ - struct acpi_processor_cx *x = a, *y = b; + for (i = 1; i < length; i++) { + if (!states[i].valid) + continue; - if (!(x->valid && y->valid)) - return; - swap(x->latency, y->latency); + for (j = i - 1, k = i; j >= 0; j--) { + if (!states[j].valid) + continue; + + if (states[j].latency > states[k].latency) + swap(states[j].latency, states[k].latency); + + k = j; + } + } } static int acpi_processor_power_verify(struct acpi_processor *pr) @@ -449,10 +447,7 @@ static int acpi_processor_power_verify(struct acpi_processor *pr) if (buggy_latency) { pr_notice("FW issue: working around C-state latencies out of order\n"); - sort(&pr->power.states[1], max_cstate, - sizeof(struct acpi_processor_cx), - acpi_cst_latency_cmp, - acpi_cst_latency_swap); + acpi_cst_latency_sort(&pr->power.states[1], max_cstate); } lapic_timer_propagate_broadcast(pr);