93 lines
3.6 KiB
Diff
93 lines
3.6 KiB
Diff
From 44285722649a364928853647fad5ad2d9be3b488 Mon Sep 17 00:00:00 2001
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Message-Id: <44285722649a364928853647fad5ad2d9be3b488.1507237259.git.Jim.Somerville@windriver.com>
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In-Reply-To: <2a9fb6a58e40e8604d97223603111e869bb774b1.1507237258.git.Jim.Somerville@windriver.com>
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References: <2a9fb6a58e40e8604d97223603111e869bb774b1.1507237258.git.Jim.Somerville@windriver.com>
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From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
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Date: Fri, 24 Feb 2017 13:25:14 +0100
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Subject: [PATCH 22/24] cpuidle: menu: Avoid taking spinlock for accessing QoS
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values
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[commit 6dbf5cea05a7098a69f294c96b6d76f08562cae5 from linux-stable ]
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After commit 9908859acaa9 (cpuidle/menu: add per CPU PM QoS resume
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latency consideration) the cpuidle menu governor calls
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dev_pm_qos_read_value() on CPU devices to read the current resume latency QoS
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constraint values for them. That function takes a spinlock to prevent the
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device's power.qos pointer from becoming NULL during the access which is a
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problem for the RT patchset where spinlocks are converted into mutexes and
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the idle loop stops working.
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However, it is not even necessary for the menu governor to take
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that spinlock, because the power.qos pointer accessed under it
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cannot be modified during the access anyway.
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For this reason, introduce a "raw" routine for accessing device
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QoS resume latency constraints without locking and use it in the
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menu governor.
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Fixes: 9908859acaa9 (cpuidle/menu: add per CPU PM QoS resume latency consideration)
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Acked-by: Alex Shi <alex.shi@linaro.org>
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Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Signed-off-by: Alex Kozyrev <alex.kozyrev@windriver.com>
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Signed-off-by: Jim Somerville <Jim.Somerville@windriver.com>
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---
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drivers/base/power/qos.c | 3 +--
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drivers/cpuidle/governors/menu.c | 2 +-
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include/linux/pm_qos.h | 6 ++++++
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3 files changed, 8 insertions(+), 3 deletions(-)
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diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
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index 2f8ac59..08a4cec 100644
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--- a/drivers/base/power/qos.c
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+++ b/drivers/base/power/qos.c
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@@ -104,8 +104,7 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_flags);
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*/
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s32 __dev_pm_qos_read_value(struct device *dev)
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{
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- return IS_ERR_OR_NULL(dev->power.qos) ?
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- 0 : pm_qos_read_value(&dev->power.qos->latency);
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+ return dev_pm_qos_raw_read_value(dev);
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}
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/**
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diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
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index fe2dcb8..f9861fd 100644
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--- a/drivers/cpuidle/governors/menu.c
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+++ b/drivers/cpuidle/governors/menu.c
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@@ -265,7 +265,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
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int i;
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int multiplier;
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struct timespec t;
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- int resume_latency = dev_pm_qos_read_value(device);
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+ int resume_latency = dev_pm_qos_raw_read_value(device);
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if (data->needs_update) {
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menu_update(drv, dev);
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diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
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index 5281e7f..1d8b629 100644
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--- a/include/linux/pm_qos.h
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+++ b/include/linux/pm_qos.h
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@@ -217,6 +217,11 @@ static inline s32 dev_pm_qos_requested_flags(struct device *dev)
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{
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return dev->power.qos->flags_req->data.flr.flags;
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}
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+static inline s32 dev_pm_qos_raw_read_value(struct device *dev)
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+{
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+ return IS_ERR_OR_NULL(dev->power.qos) ?
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+ 0 : pm_qos_read_value(&dev->power.qos->latency);
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+}
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#else
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static inline int dev_pm_qos_expose_latency_limit(struct device *dev, s32 value)
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{ return 0; }
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@@ -236,6 +241,7 @@ static inline void dev_pm_qos_hide_latency_tolerance(struct device *dev) {}
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static inline s32 dev_pm_qos_requested_latency(struct device *dev) { return 0; }
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static inline s32 dev_pm_qos_requested_flags(struct device *dev) { return 0; }
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+static inline s32 dev_pm_qos_raw_read_value(struct device *dev) { return 0; }
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#endif
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#endif
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--
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1.8.3.1
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