Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
+63
-35
+3
-1
Documentation/ABI/testing/sysfs-devices-power
+3
-1
Documentation/ABI/testing/sysfs-devices-power
···
211
211
device, after it has been suspended at run time, from a resume
212
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request to the moment the device will be ready to process I/O,
213
213
in microseconds. If it is equal to 0, however, this means that
214
-
the PM QoS resume latency may be arbitrary.
214
+
the PM QoS resume latency may be arbitrary and the special value
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+
"n/a" means that user space cannot accept any resume latency at
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+
all for the given device.
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Not all drivers support this attribute. If it isn't supported,
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219
it is not present.
+2
-1
drivers/base/cpu.c
+2
-1
drivers/base/cpu.c
···
377
377
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per_cpu(cpu_sys_devices, num) = &cpu->dev;
379
379
register_cpu_under_node(num, cpu_to_node(num));
380
-
dev_pm_qos_expose_latency_limit(&cpu->dev, 0);
380
+
dev_pm_qos_expose_latency_limit(&cpu->dev,
381
+
PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
381
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return 0;
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384
}
+30
-23
drivers/base/power/domain_governor.c
+30
-23
drivers/base/power/domain_governor.c
···
14
14
static int dev_update_qos_constraint(struct device *dev, void *data)
15
15
{
16
16
s64 *constraint_ns_p = data;
17
-
s32 constraint_ns = -1;
17
+
s64 constraint_ns = -1;
18
18
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if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
20
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constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
21
21
22
-
if (constraint_ns < 0) {
22
+
if (constraint_ns < 0)
23
23
constraint_ns = dev_pm_qos_read_value(dev);
24
-
constraint_ns *= NSEC_PER_USEC;
25
-
}
26
-
if (constraint_ns == 0)
24
+
25
+
if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
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26
return 0;
28
27
29
-
/*
30
-
* constraint_ns cannot be negative here, because the device has been
31
-
* suspended.
32
-
*/
33
-
if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
28
+
constraint_ns *= NSEC_PER_USEC;
29
+
30
+
if (constraint_ns < *constraint_ns_p || *constraint_ns_p < 0)
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31
*constraint_ns_p = constraint_ns;
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32
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33
return 0;
···
60
63
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64
spin_unlock_irqrestore(&dev->power.lock, flags);
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65
63
-
if (constraint_ns < 0)
66
+
if (constraint_ns == 0)
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return false;
65
68
66
-
constraint_ns *= NSEC_PER_USEC;
69
+
if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
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+
constraint_ns = -1;
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+
else
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+
constraint_ns *= NSEC_PER_USEC;
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+
67
74
/*
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* We can walk the children without any additional locking, because
69
76
* they all have been suspended at this point and their
···
77
76
device_for_each_child(dev, &constraint_ns,
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77
dev_update_qos_constraint);
79
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80
-
if (constraint_ns > 0) {
81
-
constraint_ns -= td->suspend_latency_ns +
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-
td->resume_latency_ns;
83
-
if (constraint_ns == 0)
84
-
return false;
79
+
if (constraint_ns < 0) {
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+
/* The children have no constraints. */
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+
td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
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+
td->cached_suspend_ok = true;
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+
} else {
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+
constraint_ns -= td->suspend_latency_ns + td->resume_latency_ns;
85
+
if (constraint_ns > 0) {
86
+
td->effective_constraint_ns = constraint_ns;
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+
td->cached_suspend_ok = true;
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+
} else {
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+
td->effective_constraint_ns = 0;
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+
}
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}
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-
td->effective_constraint_ns = constraint_ns;
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-
td->cached_suspend_ok = constraint_ns >= 0;
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92
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/*
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94
* The children have been suspended already, so we don't need to take
···
151
145
td = &to_gpd_data(pdd)->td;
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constraint_ns = td->effective_constraint_ns;
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147
/* default_suspend_ok() need not be called before us. */
154
-
if (constraint_ns < 0) {
148
+
if (constraint_ns < 0)
155
149
constraint_ns = dev_pm_qos_read_value(pdd->dev);
156
-
constraint_ns *= NSEC_PER_USEC;
157
-
}
158
-
if (constraint_ns == 0)
150
+
151
+
if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
159
152
continue;
153
+
154
+
constraint_ns *= NSEC_PER_USEC;
160
155
161
156
/*
162
157
* constraint_ns cannot be negative here, because the device has
+1
-1
drivers/base/power/qos.c
+1
-1
drivers/base/power/qos.c
···
189
189
plist_head_init(&c->list);
190
190
c->target_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
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191
c->default_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
192
-
c->no_constraint_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
192
+
c->no_constraint_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
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c->type = PM_QOS_MIN;
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c->notifiers = n;
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+1
-1
drivers/base/power/runtime.c
+1
-1
drivers/base/power/runtime.c
···
253
253
|| (dev->power.request_pending
254
254
&& dev->power.request == RPM_REQ_RESUME))
255
255
retval = -EAGAIN;
256
-
else if (__dev_pm_qos_read_value(dev) < 0)
256
+
else if (__dev_pm_qos_read_value(dev) == 0)
257
257
retval = -EPERM;
258
258
else if (dev->power.runtime_status == RPM_SUSPENDED)
259
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retval = 1;
+21
-4
drivers/base/power/sysfs.c
+21
-4
drivers/base/power/sysfs.c
···
218
218
struct device_attribute *attr,
219
219
char *buf)
220
220
{
221
-
return sprintf(buf, "%d\n", dev_pm_qos_requested_resume_latency(dev));
221
+
s32 value = dev_pm_qos_requested_resume_latency(dev);
222
+
223
+
if (value == 0)
224
+
return sprintf(buf, "n/a\n");
225
+
else if (value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
226
+
value = 0;
227
+
228
+
return sprintf(buf, "%d\n", value);
222
229
}
223
230
224
231
static ssize_t pm_qos_resume_latency_store(struct device *dev,
···
235
228
s32 value;
236
229
int ret;
237
230
238
-
if (kstrtos32(buf, 0, &value))
239
-
return -EINVAL;
231
+
if (!kstrtos32(buf, 0, &value)) {
232
+
/*
233
+
* Prevent users from writing negative or "no constraint" values
234
+
* directly.
235
+
*/
236
+
if (value < 0 || value == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)
237
+
return -EINVAL;
240
238
241
-
if (value < 0)
239
+
if (value == 0)
240
+
value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;
241
+
} else if (!strcmp(buf, "n/a") || !strcmp(buf, "n/a\n")) {
242
+
value = 0;
243
+
} else {
242
244
return -EINVAL;
245
+
}
243
246
244
247
ret = dev_pm_qos_update_request(dev->power.qos->resume_latency_req,
245
248
value);
+3
-2
include/linux/pm_qos.h
+3
-2
include/linux/pm_qos.h
···
27
27
PM_QOS_FLAGS_ALL,
28
28
};
29
29
30
-
#define PM_QOS_DEFAULT_VALUE -1
30
+
#define PM_QOS_DEFAULT_VALUE (-1)
31
+
#define PM_QOS_LATENCY_ANY S32_MAX
31
32
32
33
#define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
33
34
#define PM_QOS_NETWORK_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC)
34
35
#define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0
35
36
#define PM_QOS_MEMORY_BANDWIDTH_DEFAULT_VALUE 0
36
37
#define PM_QOS_RESUME_LATENCY_DEFAULT_VALUE 0
38
+
#define PM_QOS_RESUME_LATENCY_NO_CONSTRAINT PM_QOS_LATENCY_ANY
37
39
#define PM_QOS_LATENCY_TOLERANCE_DEFAULT_VALUE 0
38
40
#define PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT (-1)
39
-
#define PM_QOS_LATENCY_ANY ((s32)(~(__u32)0 >> 1))
40
41
41
42
#define PM_QOS_FLAG_NO_POWER_OFF (1 << 0)
42
43
#define PM_QOS_FLAG_REMOTE_WAKEUP (1 << 1)