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psi-util: fix error handling

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We checked ERRNO_IS_NOT_SUPPORTED on a possible positive non-error code,
which isn't right.

Fix that. Also add caching, since we are about to call this more often.

(cherry picked from commit 90ec8ebe33)
(cherry picked from commit 5ee19fdfa0)
This commit is contained in:
Lennart Poettering 2023-02-27 19:02:41 +01:00 committed by Zbigniew Jędrzejewski-Szmek
parent 30eae23c4a
commit 8e6234064d
1 changed files with 15 additions and 9 deletions
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24
src/shared/psi-util.c
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@ -106,18 +106,24 @@ int read_resource_pressure(const char *path, PressureType type, ResourcePressure
}
int is_pressure_supported(void) {
/* The pressure files, both under /proc and in cgroups, will exist
* even if the kernel has PSI support disabled; we have to read
* the file to make sure it doesn't return -EOPNOTSUPP */
FOREACH_STRING(p, "/proc/pressure/cpu", "/proc/pressure/io", "/proc/pressure/memory") {
int r;
static thread_local int cached = -1;
int r;
/* The pressure files, both under /proc/ and in cgroups, will exist even if the kernel has PSI
* support disabled; we have to read the file to make sure it doesn't return -EOPNOTSUPP */
if (cached >= 0)
return cached;
FOREACH_STRING(p, "/proc/pressure/cpu", "/proc/pressure/io", "/proc/pressure/memory") {
r = read_virtual_file(p, 0, NULL, NULL);
if (r == -ENOENT || ERRNO_IS_NOT_SUPPORTED(r))
return 0;
if (r < 0)
if (r < 0) {
if (r == -ENOENT || ERRNO_IS_NOT_SUPPORTED(r))
return (cached = false);
return r;
}
}
return 1;
return (cached = true);
}