cgroupv2: fix CPUQuota parsing

CPUQuota can return "max PERIOD", in this case, we detect "max"
and return `-1, nil`, which for the current usecase of detecting
cpu-num from quota should be sufficient.

Signed-off-by: Daniel Dao <dqminh89@gmail.com>

runsc/cgroup/cgroup_v2.go

@@ -234,11 +234,21 @@ func (c *cgroupV2) CPUQuota() (float64, error) {
 	if err != nil {
 		return -1, err
 	}
-	data := strings.SplitN(cpuMax, " ", 2)
+
+	return parseCPUQuota(cpuMax)
+}
+
+func parseCPUQuota(cpuMax string) (float64, error) {
+	data := strings.SplitN(strings.TrimSpace(cpuMax), " ", 2)
 	if len(data) != 2 {
 		return -1, fmt.Errorf("invalid cpu.max data %q", cpuMax)
 	}
 
+	// no cpu limit if quota is max
+	if data[0] == "max" {
+		return -1, nil
+	}
+
 	quota, err := strconv.ParseInt(data[0], 10, 64)
 	if err != nil {
 		return -1, err
@@ -253,6 +263,7 @@ func (c *cgroupV2) CPUQuota() (float64, error) {
 		return -1, err
 	}
 	return float64(quota) / float64(period), nil
+
 }
 
 // CPUUsage returns the total CPU usage of the cgroup.

runsc/cgroup/cgroup_v2_test.go

@@ -197,3 +197,46 @@ func TestConvertMemorySwapToCgroupV2Value(t *testing.T) {
 		}
 	}
 }
+
+func TestParseCPUQuota(t *testing.T) {
+	cases := []struct {
+		quota    string
+		expected float64
+		expErr   bool
+	}{
+		{
+			quota:    "max 100000\n",
+			expected: -1,
+		},
+		{
+			quota:    "10000 100000",
+			expected: 0.1,
+		},
+		{
+			quota:    "20000 100000\n",
+			expected: 0.2,
+		},
+
+		{
+			quota:    "-1",
+			expected: -1,
+			expErr:   true,
+		},
+	}
+
+	for _, c := range cases {
+		res, err := parseCPUQuota(c.quota)
+		if c.expErr {
+			if err == nil {
+				t.Errorf("quota: %q, expected error, got %.2f, nil", c.quota, res)
+			}
+			continue
+		}
+		if err != nil {
+			t.Errorf("quota: %q, expected success, got error %s", c.quota, err)
+		}
+		if res != c.expected {
+			t.Errorf("quota: %q, expected %.2f, got error %.2f", c.quota, c.expected, res)
+		}
+	}
+}

runsc/sandbox/sandbox.go

@@ -777,7 +777,7 @@ func (s *Sandbox) createSandboxProcess(conf *config.Config, args *Args, startSyn
 
 			quota, err := s.CgroupJSON.Cgroup.CPUQuota()
 			if err != nil {
-				return fmt.Errorf("getting cpu qouta from cgroups: %v", err)
+				return fmt.Errorf("getting cpu quota from cgroups: %v", err)
 			}
 			if n := int(math.Ceil(quota)); n > 0 {
 				if n < minCPUs {