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shared/hibernate-util: drop support for kernels lacking /sys/power/resume_offset

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The current fallback path is actually unreliable, given
the kernel *supports* setting the resume offset through
cmdline after all, but just not exposed under /sys/.
For v258 let's drop it hence.

I didn't bump the baseline to 4.17, but merely documented
new requirement in README, because there's certainly more
compat stuff to drop between 4.3 and 4.17, and README is
a useful list for things to kill. We'll get to 5.4 eventually.
This commit is contained in:
Mike Yuan 2025-01-02 04:32:00 +01:00
parent 733bc1aee8
commit de69879b62
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GPG Key ID: 417471C0A40F58B3
2 changed files with 14 additions and 32 deletions
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2
README
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@ -36,7 +36,7 @@ REQUIREMENTS:
≥ 4.10 for cgroup-bpf egress and ingress hooks
≥ 4.11 for nsfs
≥ 4.15 for cgroup-bpf device hook and cpu controller in cgroup v2
≥ 4.17 for cgroup-bpf socket address hooks
≥ 4.17 for cgroup-bpf socket address hooks and /sys/power/resume_offset
≥ 4.20 for PSI (used by systemd-oomd)
≥ 5.2 for cgroup freezer
≥ 5.3 for bounded loops in BPF program

44
src/shared/hibernate-util.c
View File

@ -146,19 +146,14 @@ static int read_resume_config(dev_t *ret_devno, uint64_t *ret_offset) {
return log_debug_errno(r, "Failed to parse /sys/power/resume devno '%s': %m", devno_str);
r = read_one_line_file("/sys/power/resume_offset", &offset_str);
if (r == -ENOENT) {
log_debug_errno(r, "Kernel does not expose resume_offset, skipping.");
offset = UINT64_MAX;
} else if (r < 0)
if (r < 0)
return log_debug_errno(r, "Failed to read /sys/power/resume_offset: %m");
else {
r = safe_atou64(offset_str, &offset);
if (r < 0)
return log_debug_errno(r,
"Failed to parse /sys/power/resume_offset '%s': %m", offset_str);
}
if (devno == 0 && offset > 0 && offset != UINT64_MAX)
r = safe_atou64(offset_str, &offset);
if (r < 0)
return log_debug_errno(r, "Failed to parse /sys/power/resume_offset '%s': %m", offset_str);
if (devno == 0 && offset > 0)
return log_debug_errno(SYNTHETIC_ERRNO(ENOMEDIUM),
"Found populated /sys/power/resume_offset (%" PRIu64 ") but /sys/power/resume is not set, refusing.",
offset);
@ -375,10 +370,9 @@ int find_suitable_hibernation_device_full(HibernationDevice *ret_device, uint64_
if (resume_config_devno > 0) {
if (swap->devno == resume_config_devno &&
(!swap->swapfile || resume_config_offset == UINT64_MAX || swap->offset == resume_config_offset)) {
(!swap->swapfile || swap->offset == resume_config_offset)) {
/* /sys/power/resume (resume=) is set, and the calculated swap file offset
* matches with /sys/power/resume_offset. If /sys/power/resume_offset is not
* exposed, we can't do proper check anyway, so use the found swap file too. */
* matches with /sys/power/resume_offset. */
entry = swap;
break;
}
@ -496,28 +490,16 @@ int write_resume_config(dev_t devno, uint64_t offset, const char *device) {
devno_str = FORMAT_DEVNUM(devno);
xsprintf(offset_str, "%" PRIu64, offset);
/* We write the offset first since it's safer. Note that this file is only available in 4.17+, so
* fail gracefully if it doesn't exist and we're only overwriting it with 0. */
r = write_string_file("/sys/power/resume_offset", offset_str, WRITE_STRING_FILE_DISABLE_BUFFER);
if (r == -ENOENT) {
if (offset != 0)
return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
"Can't configure swap file offset %s, kernel does not support /sys/power/resume_offset. Refusing.",
offset_str);
log_warning_errno(r, "/sys/power/resume_offset is unavailable, skipping writing swap file offset.");
} else if (r < 0)
return log_error_errno(r,
"Failed to write swap file offset %s to /sys/power/resume_offset for device '%s': %m",
if (r < 0)
return log_error_errno(r, "Failed to write swap file offset %s to /sys/power/resume_offset for device '%s': %m",
offset_str, device);
else
log_debug("Wrote resume_offset=%s for device '%s' to /sys/power/resume_offset.",
offset_str, device);
log_debug("Wrote resume_offset=%s for device '%s' to /sys/power/resume_offset.",
offset_str, device);
r = write_string_file("/sys/power/resume", devno_str, WRITE_STRING_FILE_DISABLE_BUFFER);
if (r < 0)
return log_error_errno(r,
"Failed to write device '%s' (%s) to /sys/power/resume: %m",
return log_error_errno(r, "Failed to write device '%s' (%s) to /sys/power/resume: %m",
device, devno_str);
log_debug("Wrote resume=%s for device '%s' to /sys/power/resume.", devno_str, device);