core: refactor cpu shares/blockio weight cgroup logic

Let's stop using the "unsigned long" type for weights/shares, and let's
just use uint64_t for this, as that's what we expose on the bus.

Unify parsers, and always validate the range for these fields.

Correct the default blockio weight to 500, since that's what the kernel
actually uses.

When parsing the weight/shares settings from unit files accept the empty
string as a way to reset the weight/shares value. When getting it via
the bus, uniformly map (uint64_t) -1 to unset.

Open up StartupCPUShares= and StartupBlockIOWeight= to transient units.

2 files changed, 67 insertions, 0 deletions

diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c
index 6099dc8721..4bf08cfe03 100644
--- a/src/basic/cgroup-util.c
+++ b/src/basic/cgroup-util.c
@@ -2207,6 +2207,46 @@ bool cg_is_legacy_wanted(void) {
         return !cg_is_unified_wanted();
 }
 
+int cg_cpu_shares_parse(const char *s, uint64_t *ret) {
+        uint64_t u;
+        int r;
+
+        if (isempty(s)) {
+                *ret = CGROUP_CPU_SHARES_INVALID;
+                return 0;
+        }
+
+        r = safe_atou64(s, &u);
+        if (r < 0)
+                return r;
+
+        if (u < CGROUP_CPU_SHARES_MIN || u > CGROUP_CPU_SHARES_MAX)
+                return -ERANGE;
+
+        *ret = u;
+        return 0;
+}
+
+int cg_blkio_weight_parse(const char *s, uint64_t *ret) {
+        uint64_t u;
+        int r;
+
+        if (isempty(s)) {
+                *ret = CGROUP_BLKIO_WEIGHT_INVALID;
+                return 0;
+        }
+
+        r = safe_atou64(s, &u);
+        if (r < 0)
+                return r;
+
+        if (u < CGROUP_BLKIO_WEIGHT_MIN || u > CGROUP_BLKIO_WEIGHT_MAX)
+                return -ERANGE;
+
+        *ret = u;
+        return 0;
+}
+
 static const char *cgroup_controller_table[_CGROUP_CONTROLLER_MAX] = {
         [CGROUP_CONTROLLER_CPU] = "cpu",
         [CGROUP_CONTROLLER_CPUACCT] = "cpuacct",
diff --git a/src/basic/cgroup-util.h b/src/basic/cgroup-util.h
index 7e1b4f9c72..33ca28cab7 100644
--- a/src/basic/cgroup-util.h
+++ b/src/basic/cgroup-util.h
@@ -53,6 +53,30 @@ typedef enum CGroupMask {
         _CGROUP_MASK_ALL = CGROUP_CONTROLLER_TO_MASK(_CGROUP_CONTROLLER_MAX) - 1
 } CGroupMask;
 
+/* Special values for the cpu.shares attribute */
+#define CGROUP_CPU_SHARES_INVALID ((uint64_t) -1)
+#define CGROUP_CPU_SHARES_MIN UINT64_C(2)
+#define CGROUP_CPU_SHARES_MAX UINT64_C(262144)
+#define CGROUP_CPU_SHARES_DEFAULT UINT64_C(1024)
+
+static inline bool CGROUP_CPU_SHARES_IS_OK(uint64_t x) {
+        return
+            x == CGROUP_CPU_SHARES_INVALID ||
+            (x >= CGROUP_CPU_SHARES_MIN && x <= CGROUP_CPU_SHARES_MAX);
+}
+
+/* Special values for the blkio.weight attribute */
+#define CGROUP_BLKIO_WEIGHT_INVALID ((uint64_t) -1)
+#define CGROUP_BLKIO_WEIGHT_MIN UINT64_C(10)
+#define CGROUP_BLKIO_WEIGHT_MAX UINT64_C(1000)
+#define CGROUP_BLKIO_WEIGHT_DEFAULT UINT64_C(500)
+
+static inline bool CGROUP_BLKIO_WEIGHT_IS_OK(uint64_t x) {
+        return
+            x == CGROUP_BLKIO_WEIGHT_INVALID ||
+            (x >= CGROUP_BLKIO_WEIGHT_MIN && x <= CGROUP_BLKIO_WEIGHT_MAX);
+}
+
 /*
  * General rules:
  *
@@ -161,3 +185,6 @@ bool cg_is_legacy_wanted(void);
 
 const char* cgroup_controller_to_string(CGroupController c) _const_;
 CGroupController cgroup_controller_from_string(const char *s) _pure_;
+
+int cg_cpu_shares_parse(const char *s, uint64_t *ret);
+int cg_blkio_weight_parse(const char *s, uint64_t *ret);