Merge tag 'pm-4.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fix from Rafael Wysocki:
"This fixes a device power management quality of service (PM QoS)
framework implementation issue causing 'no restriction' requests for
device resume latency, including 'no restriction' set by user space,
to effectively override requests with specific device resume latency
requirements.
It is late in the cycle, but the bug in question is in the 'user space
can trigger unexpected behavior' category and the fix is
stable-candidate, so here it goes"
* tag 'pm-4.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM / QoS: Fix device resume latency PM QoS
diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power
index 676fdf5..5cbb6f0 100644
--- a/Documentation/ABI/testing/sysfs-devices-power
+++ b/Documentation/ABI/testing/sysfs-devices-power
@@ -211,7 +211,9 @@
device, after it has been suspended at run time, from a resume
request to the moment the device will be ready to process I/O,
in microseconds. If it is equal to 0, however, this means that
- the PM QoS resume latency may be arbitrary.
+ the PM QoS resume latency may be arbitrary and the special value
+ "n/a" means that user space cannot accept any resume latency at
+ all for the given device.
Not all drivers support this attribute. If it isn't supported,
it is not present.
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 321cd7b..227bac5 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -377,7 +377,8 @@
per_cpu(cpu_sys_devices, num) = &cpu->dev;
register_cpu_under_node(num, cpu_to_node(num));
- dev_pm_qos_expose_latency_limit(&cpu->dev, 0);
+ dev_pm_qos_expose_latency_limit(&cpu->dev,
+ PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
return 0;
}
diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c
index 281f949..51751cc 100644
--- a/drivers/base/power/domain_governor.c
+++ b/drivers/base/power/domain_governor.c
@@ -14,23 +14,20 @@
static int dev_update_qos_constraint(struct device *dev, void *data)
{
s64 *constraint_ns_p = data;
- s32 constraint_ns = -1;
+ s64 constraint_ns = -1;
if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
- if (constraint_ns < 0) {
+ if (constraint_ns < 0)
constraint_ns = dev_pm_qos_read_value(dev);
- constraint_ns *= NSEC_PER_USEC;
- }
- if (constraint_ns == 0)
+
+ if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
return 0;
- /*
- * constraint_ns cannot be negative here, because the device has been
- * suspended.
- */
- if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
+ constraint_ns *= NSEC_PER_USEC;
+
+ if (constraint_ns < *constraint_ns_p || *constraint_ns_p < 0)
*constraint_ns_p = constraint_ns;
return 0;
@@ -63,10 +60,14 @@
spin_unlock_irqrestore(&dev->power.lock, flags);
- if (constraint_ns < 0)
+ if (constraint_ns == 0)
return false;
- constraint_ns *= NSEC_PER_USEC;
+ if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
+ constraint_ns = -1;
+ else
+ constraint_ns *= NSEC_PER_USEC;
+
/*
* We can walk the children without any additional locking, because
* they all have been suspended at this point and their
@@ -76,14 +77,19 @@
device_for_each_child(dev, &constraint_ns,
dev_update_qos_constraint);
- if (constraint_ns > 0) {
- constraint_ns -= td->suspend_latency_ns +
- td->resume_latency_ns;
- if (constraint_ns == 0)
- return false;
+ if (constraint_ns < 0) {
+ /* The children have no constraints. */
+ td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
+ td->cached_suspend_ok = true;
+ } else {
+ constraint_ns -= td->suspend_latency_ns + td->resume_latency_ns;
+ if (constraint_ns > 0) {
+ td->effective_constraint_ns = constraint_ns;
+ td->cached_suspend_ok = true;
+ } else {
+ td->effective_constraint_ns = 0;
+ }
}
- td->effective_constraint_ns = constraint_ns;
- td->cached_suspend_ok = constraint_ns >= 0;
/*
* The children have been suspended already, so we don't need to take
@@ -145,13 +151,14 @@
td = &to_gpd_data(pdd)->td;
constraint_ns = td->effective_constraint_ns;
/* default_suspend_ok() need not be called before us. */
- if (constraint_ns < 0) {
+ if (constraint_ns < 0)
constraint_ns = dev_pm_qos_read_value(pdd->dev);
- constraint_ns *= NSEC_PER_USEC;
- }
- if (constraint_ns == 0)
+
+ if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
continue;
+ constraint_ns *= NSEC_PER_USEC;
+
/*
* constraint_ns cannot be negative here, because the device has
* been suspended.
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index 277d43a..7d29286 100644
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -189,7 +189,7 @@
plist_head_init(&c->list);
c->target_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
c->default_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
- c->no_constraint_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
+ c->no_constraint_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
c->type = PM_QOS_MIN;
c->notifiers = n;
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 7bcf80f..13e0159 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -253,7 +253,7 @@
|| (dev->power.request_pending
&& dev->power.request == RPM_REQ_RESUME))
retval = -EAGAIN;
- else if (__dev_pm_qos_read_value(dev) < 0)
+ else if (__dev_pm_qos_read_value(dev) == 0)
retval = -EPERM;
else if (dev->power.runtime_status == RPM_SUSPENDED)
retval = 1;
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 156ab57..632077f 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -218,7 +218,14 @@
struct device_attribute *attr,
char *buf)
{
- return sprintf(buf, "%d\n", dev_pm_qos_requested_resume_latency(dev));
+ s32 value = dev_pm_qos_requested_resume_latency(dev);
+
+ if (value == 0)
+ return sprintf(buf, "n/a\n");
+ else if (value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
+ value = 0;
+
+ return sprintf(buf, "%d\n", value);
}
static ssize_t pm_qos_resume_latency_store(struct device *dev,
@@ -228,11 +235,21 @@
s32 value;
int ret;
- if (kstrtos32(buf, 0, &value))
- return -EINVAL;
+ if (!kstrtos32(buf, 0, &value)) {
+ /*
+ * Prevent users from writing negative or "no constraint" values
+ * directly.
+ */
+ if (value < 0 || value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
+ return -EINVAL;
- if (value < 0)
+ if (value == 0)
+ value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
+ } else if (!strcmp(buf, "n/a") || !strcmp(buf, "n/a\n")) {
+ value = 0;
+ } else {
return -EINVAL;
+ }
ret = dev_pm_qos_update_request(dev->power.qos->resume_latency_req,
value);
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 48eaf28..aa39040 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -298,8 +298,8 @@
data->needs_update = 0;
}
- /* resume_latency is 0 means no restriction */
- if (resume_latency && resume_latency < latency_req)
+ if (resume_latency < latency_req &&
+ resume_latency != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
latency_req = resume_latency;
/* Special case when user has set very strict latency requirement */
diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index 032b559..6737a8c 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -27,16 +27,17 @@
PM_QOS_FLAGS_ALL,
};
-#define PM_QOS_DEFAULT_VALUE -1
+#define PM_QOS_DEFAULT_VALUE (-1)
+#define PM_QOS_LATENCY_ANY S32_MAX
#define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
#define PM_QOS_NETWORK_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
#define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0
#define PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE 0
#define PM_QOS_RESUME_LATENCY_DEFAULT_VALUE 0
+#define PM_QOS_RESUME_LATENCY_NO_CONSTRAINT PM_QOS_LATENCY_ANY
#define PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE 0
#define PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT (-1)
-#define PM_QOS_LATENCY_ANY ((s32)(~(__u32)0 >> 1))
#define PM_QOS_FLAG_NO_POWER_OFF (1 << 0)
#define PM_QOS_FLAG_REMOTE_WAKEUP (1 << 1)
