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Date: Sat, 8 Jan 2011 00:29:20 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Len Brown <lenb@...nel.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
"Linux-pm mailing list" <linux-pm@...ts.linux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Thomas Renninger <trenn@...e.de>
Subject: [PATCH] cpuidle: Make cpuidle_enable_device() call poll_idle_init()
From: Rafael J. Wysocki <rjw@...k.pl>
The following scenario is possible with the current cpuidle code and
the ACPI cpuidle driver:
(1) acpi_processor_cst_has_changed() is called,
(2) cpuidle_disable_device() is called,
(3) cpuidle_remove_state_sysfs() is called to remove the (presumably
outdated) states info from sysfs,
(3) acpi_processor_get_power_info() is called, the first entry in the
pr->power.states[] table is filled with zeros,
(4) acpi_processor_setup_cpuidle() is called and it doesn't fill the
first entry in pr->power.states[],
(5) cpuidle_enable_device() is called,
(6) __cpuidle_register_device() is _not_ called, since the device has
already been registered,
(7) Consequently, poll_idle_init() is _not_ called either,
(8) cpuidle_add_state_sysfs() is called to create the sysfs attributes
for the new states and it uses the bogus first table entry from
acpi_processor_get_power_info() for creating state0.
This problem will be avoided if cpuidle_enable_device() calls
poll_idle_init() for dev->registered different from zero.
Reported-by: Len Brown <len.brown@...el.com>
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
drivers/cpuidle/cpuidle.c | 80 +++++++++++++++++++++++-----------------------
1 file changed, 41 insertions(+), 39 deletions(-)
Index: linux-2.6/drivers/cpuidle/cpuidle.c
===================================================================
--- linux-2.6.orig/drivers/cpuidle/cpuidle.c
+++ linux-2.6/drivers/cpuidle/cpuidle.c
@@ -154,6 +154,45 @@ void cpuidle_resume_and_unlock(void)
EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
+#ifdef CONFIG_ARCH_HAS_CPU_RELAX
+static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
+{
+ ktime_t t1, t2;
+ s64 diff;
+ int ret;
+
+ t1 = ktime_get();
+ local_irq_enable();
+ while (!need_resched())
+ cpu_relax();
+
+ t2 = ktime_get();
+ diff = ktime_to_us(ktime_sub(t2, t1));
+ if (diff > INT_MAX)
+ diff = INT_MAX;
+
+ ret = (int) diff;
+ return ret;
+}
+
+static void poll_idle_init(struct cpuidle_device *dev)
+{
+ struct cpuidle_state *state = &dev->states[0];
+
+ cpuidle_set_statedata(state, NULL);
+
+ snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
+ snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
+ state->exit_latency = 0;
+ state->target_residency = 0;
+ state->power_usage = -1;
+ state->flags = CPUIDLE_FLAG_POLL;
+ state->enter = poll_idle;
+}
+#else
+static void poll_idle_init(struct cpuidle_device *dev) {}
+#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
+
/**
* cpuidle_enable_device - enables idle PM for a CPU
* @dev: the CPU
@@ -176,6 +215,8 @@ int cpuidle_enable_device(struct cpuidle
ret = __cpuidle_register_device(dev);
if (ret)
return ret;
+ } else {
+ poll_idle_init(dev);
}
if ((ret = cpuidle_add_state_sysfs(dev)))
@@ -232,45 +273,6 @@ void cpuidle_disable_device(struct cpuid
EXPORT_SYMBOL_GPL(cpuidle_disable_device);
-#ifdef CONFIG_ARCH_HAS_CPU_RELAX
-static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
-{
- ktime_t t1, t2;
- s64 diff;
- int ret;
-
- t1 = ktime_get();
- local_irq_enable();
- while (!need_resched())
- cpu_relax();
-
- t2 = ktime_get();
- diff = ktime_to_us(ktime_sub(t2, t1));
- if (diff > INT_MAX)
- diff = INT_MAX;
-
- ret = (int) diff;
- return ret;
-}
-
-static void poll_idle_init(struct cpuidle_device *dev)
-{
- struct cpuidle_state *state = &dev->states[0];
-
- cpuidle_set_statedata(state, NULL);
-
- snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
- snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
- state->exit_latency = 0;
- state->target_residency = 0;
- state->power_usage = -1;
- state->flags = CPUIDLE_FLAG_POLL;
- state->enter = poll_idle;
-}
-#else
-static void poll_idle_init(struct cpuidle_device *dev) {}
-#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
-
/**
* __cpuidle_register_device - internal register function called before register
* and enable routines
--
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