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on-ac-power: rework logic

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History of the function:
96788d2aa4f4b0b49874b4a240ce47d9e8485d1b assume system is running on AC power when no battery found
795e86b4f1e8a1fd440f8c817621779c6aedbdb5 ignore USB-C ports in power source mode when detecting system is running on AC power
c19a51bec40ae5e5073464e72411e7920d05d683 invert ac_power() source type check
6d89003462484c8656b698e07b9cf0a337e3818e assume ac when /sys/class/power_supply is missing
240dbaa44f8e5ad51775c776fc3ce9cd2f19f037 add ConditionACPower=

Interestingly, the return condition 'on_ac_power == found_online || !found_offline'
was there from the very beginning, and even Yu's latest change doesn't change this,
but only extends it to 'on_ac_power == found_online || !found_offline || !found_battery'.
This means that any system with no AC power supply will be unconditionally classified
as on_ac_power.

Let's change the logic: if we have an online AC supply, answer is "yes". If no
supplies, but we have a battery, answer is "no". Otherwise, assume "yes", based
on the assumption that presense of a battery would at least be always reported,
even if an AC power supply might not be.

Fixes #24407. It also shouldn't impact previous fixes: assume ac when
/sys/class/power_supply is missing, ignore USB-C ports in power source mode,
assume system is running on AC power when no battery found.

(cherry picked from commit 4a52514b371bf8013e89c421dfc2405a443feef8)
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2022-08-23 16:30:05 +02:00
parent 1fc74d251e
commit 9886011356
1 changed files with 26 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
src/shared/udev-util.c
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@ -648,7 +648,7 @@ static int device_is_power_sink(sd_device *device) {
int on_ac_power(void) {
_cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
bool found_offline = false, found_online = false, found_battery = false;
bool found_ac_online = false, found_battery = false;
sd_device *d;
int r;
@ -665,22 +665,15 @@ int on_ac_power(void) {
return r;
FOREACH_DEVICE(e, d) {
const char *val;
unsigned v;
r = sd_device_get_sysattr_value(d, "type", &val);
if (r < 0) {
log_device_debug_errno(d, r, "Failed to read 'type' sysfs attribute, ignoring device: %m");
continue;
}
/* We assume every power source is AC, except for batteries. See
/* See
* https://github.com/torvalds/linux/blob/4eef766b7d4d88f0b984781bc1bcb574a6eafdc7/include/linux/power_supply.h#L176
* for defined power source types. Also see:
* https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-class-power */
if (streq(val, "Battery")) {
found_battery = true;
log_device_debug(d, "The power supply is battery, ignoring device.");
const char *val;
r = sd_device_get_sysattr_value(d, "type", &val);
if (r < 0) {
log_device_debug_errno(d, r, "Failed to read 'type' sysfs attribute, ignoring device: %m");
continue;
}
@ -696,36 +689,33 @@ int on_ac_power(void) {
}
}
r = sd_device_get_sysattr_value(d, "online", &val);
if (r < 0) {
log_device_debug_errno(d, r, "Failed to read 'online' sysfs attribute, ignoring device: %m");
bool is_battery = streq(val, "Battery");
if (is_battery) {
found_battery = true;
log_device_debug(d, "The power supply is battery.");
continue;
}
r = safe_atou(val, &v);
r = device_get_sysattr_unsigned(d, "online", NULL);
if (r < 0) {
log_device_debug_errno(d, r, "Failed to parse 'online' attribute, ignoring device: %m");
log_device_debug_errno(d, r, "Failed to query 'online' sysfs attribute: %m");
continue;
}
} else if (r > 0) /* At least 1 and 2 are defined as different types of 'online' */
found_ac_online = true;
if (v > 0) /* At least 1 and 2 are defined as different types of 'online' */
found_online = true;
else
found_offline = true;
log_device_debug(d, "The power supply is currently %s.", v > 0 ? "online" : "offline");
log_device_debug(d, "The power supply is currently %s.", r > 0 ? "online" : "offline");
}
if (found_online)
log_debug("Found at least one online non-battery power supply, system is running on AC power.");
else if (!found_offline)
log_debug("Found no offline non-battery power supply, assuming system is running on AC power.");
else if (!found_battery)
log_debug("Found no battery, assuming system is running on AC power.");
else
log_debug("All non-battery power supplies are offline, assuming system is running with battery.");
return found_online || !found_offline || !found_battery;
if (found_ac_online) {
log_debug("Found at least one online non-battery power supply, system is running on AC.");
return true;
} else if (found_battery) {
log_debug("Found battery and no online power sources, assuming system is running from battery.");
return false;
} else {
log_debug("No power supply reported online and no battery, assuming system is running on AC.");
return true;
}
}
bool udev_available(void) {