From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 727E9FC19; Thu, 25 Jul 2024 14:49:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721918975; cv=none; b=BwQFxC12OOwa7OyNjvictHA5NcJiQ/Y8HQL04gi/p3Cb2hzUPjH+Iu1uG/m/IkD0vtZkB1zlewqKOcGRCXcVyJKSyTBw0MrUcqGXG2db+lcQu1kfTU3QQA4qDK9wzSyrhPaLNlH4MOKicA7+WKYchmoRNbJVqbGBbn04aYxgyUo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721918975; c=relaxed/simple; bh=zyvsEul2POd/gvv2SW5qzc3OIjtv+1XaKdMgfweFXl8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ao1XBSfSuU/HNqNnGRQmlHMbEvw64Pvct0g4hOYPbUZ0x4CUQwv2tSLjw6/2gsqq2IXHpu69oIe8t624K8Xve6sqd1azqB/CZPh5n6o1+WFgVGAxJwLTODCuFeYhxh9kUXKQUND22eOmoyZg8Vei3ZqIaLgjK0RrlvVrmfAByaY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FlhmkIAI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FlhmkIAI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ECFEDC116B1; Thu, 25 Jul 2024 14:49:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1721918975; bh=zyvsEul2POd/gvv2SW5qzc3OIjtv+1XaKdMgfweFXl8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FlhmkIAIBWm90D/r6LqtXMfGoZbD2COCCWOBJDK35na+x3Kn0FEwIdWTt497nAPXH XkADUxYyxEZIB616AF8smvJP7e8CFPL1sKRQ6hUDZHyGaHyc/Olknknfsgq5p+J0HT QCg1PkAW9blYTQS6ybLvsTnl2fWRXoTWexLlZ458= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Julian Sikorski , Kuan-Wei Chiu , "Rafael J. Wysocki" Subject: [PATCH 5.10 45/59] ACPI: processor_idle: Fix invalid comparison with insertion sort for latency Date: Thu, 25 Jul 2024 16:37:35 +0200 Message-ID: <20240725142734.963582984@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240725142733.262322603@linuxfoundation.org> References: <20240725142733.262322603@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuan-Wei Chiu commit 233323f9b9f828cd7cd5145ad811c1990b692542 upstream. 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") 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 Cc: All applicable Link: https://patch.msgid.link/20240701205639.117194-1-visitorckw@gmail.com Signed-off-by: Rafael J. Wysocki Signed-off-by: Kuan-Wei Chiu Signed-off-by: Greg Kroah-Hartman --- drivers/acpi/processor_idle.c | 40 ++++++++++++++++------------------------ 1 file changed, 16 insertions(+), 24 deletions(-) --- 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 @@ -390,28 +389,24 @@ static void acpi_processor_power_verify_ return; } -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; - u32 tmp; + for (i = 1; i < length; i++) { + if (!states[i].valid) + continue; - if (!(x->valid && y->valid)) - return; - tmp = x->latency; - x->latency = y->latency; - y->latency = tmp; + 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) @@ -456,10 +451,7 @@ static int acpi_processor_power_verify(s 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);