From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754054AbcAOX45 (ORCPT ); Fri, 15 Jan 2016 18:56:57 -0500 Received: from v094114.home.net.pl ([79.96.170.134]:61399 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753829AbcAOX4e (ORCPT ); Fri, 15 Jan 2016 18:56:34 -0500 From: "Rafael J. Wysocki" To: Peter Zijlstra Cc: Linux PM list , Linux Kernel Mailing List , Ingo Molnar , Daniel Lezcano , Sudeep Holla Subject: [PATCH 1/2] sched / idle: Drop default_idle_call() fallback from call_cpuidle() Date: Sat, 16 Jan 2016 00:54:53 +0100 Message-ID: <2393290.LAksQzHH19@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.4.0; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1621492.NI2xz9vt7M@vostro.rjw.lan> References: <1621492.NI2xz9vt7M@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki After commit 9c4b2867ed7c (cpuidle: menu: Fix menu_select() for CPUIDLE_DRIVER_STATE_START == 0) it is clear that menu_select() cannot return negative values. Moreover, ladder_select_state() will never return a negative value too, so make find_deepest_state() return non-negative values too and drop the default_idle_call() fallback from call_cpuidle(). This eliminates one branch from the idle loop and makes the governors and find_deepest_state() handle the case when all states have been disabled from sysfs consistently. Signed-off-by: Rafael J. Wysocki --- Note: Commit 9c4b2867ed7c (cpuidle: menu: Fix menu_select() for CPUIDLE_DRIVER_STATE_START == 0) is in linux-next only ATM. --- drivers/cpuidle/cpuidle.c | 6 +++--- kernel/sched/idle.c | 6 ------ 2 files changed, 3 insertions(+), 9 deletions(-) Index: linux-pm/drivers/cpuidle/cpuidle.c =================================================================== --- linux-pm.orig/drivers/cpuidle/cpuidle.c +++ linux-pm/drivers/cpuidle/cpuidle.c @@ -79,9 +79,9 @@ static int find_deepest_state(struct cpu bool freeze) { unsigned int latency_req = 0; - int i, ret = -ENXIO; + int i, ret = 0; - for (i = 0; i < drv->state_count; i++) { + for (i = 1; i < drv->state_count; i++) { struct cpuidle_state *s = &drv->states[i]; struct cpuidle_state_usage *su = &dev->states_usage[i]; @@ -243,7 +243,7 @@ int cpuidle_enter_state(struct cpuidle_d * @drv: the cpuidle driver * @dev: the cpuidle device * - * Returns the index of the idle state. + * Returns the index of the idle state. The return value must not be negative. */ int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) { Index: linux-pm/kernel/sched/idle.c =================================================================== --- linux-pm.orig/kernel/sched/idle.c +++ linux-pm/kernel/sched/idle.c @@ -97,12 +97,6 @@ void default_idle_call(void) static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev, int next_state) { - /* Fall back to the default arch idle method on errors. */ - if (next_state < 0) { - default_idle_call(); - return next_state; - } - /* * The idle task must be scheduled, it is pointless to go to idle, just * update no idle residency and return.