8197408: Bad pointer comparison and small cleanup in os_linux.cpp

Reviewed-by: bobv, stuefe

src/hotspot/os/linux/osContainer_linux.cpp

@@ -414,9 +414,9 @@ void OSContainer::init() {
 
 }
 
-char * OSContainer::container_type() {
+const char * OSContainer::container_type() {
   if (is_containerized()) {
-    return (char *)"cgroupv1";
+    return "cgroupv1";
   } else {
     return NULL;
   }

src/hotspot/os/linux/osContainer_linux.hpp

@@ -40,7 +40,7 @@ class OSContainer: AllStatic {
  public:
   static void init();
   static inline bool is_containerized();
-  static char * container_type();
+  static const char * container_type();
 
   static jlong memory_limit_in_bytes();
   static jlong memory_and_swap_limit_in_bytes();

src/hotspot/os/linux/os_linux.cpp

@@ -177,20 +177,17 @@ julong os::Linux::available_memory() {
 
   if (OSContainer::is_containerized()) {
     jlong mem_limit, mem_usage;
-    if ((mem_limit = OSContainer::memory_limit_in_bytes()) > 0) {
-      if ((mem_usage = OSContainer::memory_usage_in_bytes()) > 0) {
-        if (mem_limit > mem_usage) {
-          avail_mem = (julong)mem_limit - (julong)mem_usage;
-        } else {
-          avail_mem = 0;
+    if ((mem_limit = OSContainer::memory_limit_in_bytes()) < 1) {
+      log_debug(os, container)("container memory limit %s: " JLONG_FORMAT ", using host value",
+                             mem_limit == OSCONTAINER_ERROR ? "failed" : "unlimited", mem_limit);
     }
+    if (mem_limit > 0 && (mem_usage = OSContainer::memory_usage_in_bytes()) < 1) {
+      log_debug(os, container)("container memory usage failed: " JLONG_FORMAT ", using host value", mem_usage);
+    }
+    if (mem_limit > 0 && mem_usage > 0 ) {
+      avail_mem = mem_limit > mem_usage ? (julong)mem_limit - (julong)mem_usage : 0;
       log_trace(os)("available container memory: " JULONG_FORMAT, avail_mem);
       return avail_mem;
-      } else {
-        log_debug(os,container)("container memory usage call failed: " JLONG_FORMAT, mem_usage);
-      }
-    } else {
-      log_debug(os,container)("container memory unlimited or failed: " JLONG_FORMAT, mem_limit);
     }
   }
 
@@ -201,22 +198,18 @@ julong os::Linux::available_memory() {
 }
 
 julong os::physical_memory() {
+  jlong phys_mem = 0;
   if (OSContainer::is_containerized()) {
     jlong mem_limit;
     if ((mem_limit = OSContainer::memory_limit_in_bytes()) > 0) {
       log_trace(os)("total container memory: " JLONG_FORMAT, mem_limit);
-      return (julong)mem_limit;
-    } else {
-      if (mem_limit == OSCONTAINER_ERROR) {
-        log_debug(os,container)("container memory limit call failed");
-      }
-      if (mem_limit == -1) {
-        log_debug(os,container)("container memory unlimited, using host value");
-      }
+      return phys_mem;
     }
+    log_debug(os, container)("container memory limit %s: " JLONG_FORMAT ", using host value",
+                            mem_limit == OSCONTAINER_ERROR ? "failed" : "unlimited", mem_limit);
   }
 
-  jlong phys_mem = Linux::physical_memory();
+  phys_mem = Linux::physical_memory();
   log_trace(os)("total system memory: " JLONG_FORMAT, phys_mem);
   return phys_mem;
 }
@@ -2135,37 +2128,29 @@ void os::Linux::print_full_memory_info(outputStream* st) {
 }
 
 void os::Linux::print_container_info(outputStream* st) {
-  if (OSContainer::is_containerized()) {
+  if (!OSContainer::is_containerized()) {
+    return;
+  }
+
   st->print("container (cgroup) information:\n");
 
-    char *p = OSContainer::container_type();
-    if (p == NULL)
-      st->print("container_type() failed\n");
-    else {
-      st->print("container_type: %s\n", p);
-    }
+  const char *p_ct = OSContainer::container_type();
+  st->print("container_type: %s\n", p_ct != NULL ? p_ct : "failed");
 
-    p = OSContainer::cpu_cpuset_cpus();
-    if (p == NULL)
-      st->print("cpu_cpuset_cpus() failed\n");
-    else {
-      st->print("cpu_cpuset_cpus: %s\n", p);
+  char *p = OSContainer::cpu_cpuset_cpus();
+  st->print("cpu_cpuset_cpus: %s\n", p != NULL ? p : "failed");
   free(p);
-    }
 
   p = OSContainer::cpu_cpuset_memory_nodes();
-    if (p < 0)
-      st->print("cpu_memory_nodes() failed\n");
-    else {
-      st->print("cpu_memory_nodes: %s\n", p);
+  st->print("cpu_memory_nodes: %s\n", p != NULL ? p : "failed");
   free(p);
-    }
 
   int i = OSContainer::active_processor_count();
-    if (i < 0)
-      st->print("active_processor_count() failed\n");
-    else
+  if (i > 0) {
     st->print("active_processor_count: %d\n", i);
+  } else {
+    st->print("active_processor_count: failed\n");
+  }
 
   i = OSContainer::cpu_quota();
   st->print("cpu_quota: %d\n", i);
@@ -2192,7 +2177,6 @@ void os::Linux::print_container_info(outputStream* st) {
   st->print("memory_max_usage_in_bytes: " JLONG_FORMAT "\n", j);
   st->cr();
 }
-}
 
 void os::print_memory_info(outputStream* st) {
 

test/hotspot/jtreg/runtime/containers/cgroup/PlainRead.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test PlainRead
+ * @requires os.family == "linux"
+ * @library /testlibrary /test/lib
+ * @build sun.hotspot.WhiteBox
+ * @run driver ClassFileInstaller sun.hotspot.WhiteBox
+ *                              sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI PlainRead
+ */
+
+import jdk.test.lib.process.ProcessTools;
+import jdk.test.lib.process.OutputAnalyzer;
+import jdk.test.lib.Platform;
+import sun.hotspot.WhiteBox;
+
+public class PlainRead {
+
+    static public void match(OutputAnalyzer oa, String what, String value) {
+       oa.shouldMatch("^.*" + what + " *" + value + ".*$");
+    }
+
+    static public void noMatch(OutputAnalyzer oa, String what, String value) {
+       oa.shouldNotMatch("^.*" + what + " *" + value + ".*$");
+    }
+
+    static final String good_value = "(\\d+|-1|Unlimited)";
+    static final String bad_value = "(failed)";
+
+    static final String[] variables = {"Memory Limit is:", "CPU Shares is:", "CPU Quota is:", "CPU Period is:", "active_processor_count:"};
+
+    static public void isContainer(OutputAnalyzer oa) {
+        for (String v: variables) {
+            match(oa, v, good_value);
+        }
+        for (String v: variables) {
+            noMatch(oa, v, bad_value);
+        }
+    }
+
+    static public void isNotContainer(OutputAnalyzer oa) {
+       oa.shouldMatch("^.*Can't open /proc/self/mountinfo.*$");
+    }
+
+    public static void main(String[] args) throws Exception {
+        WhiteBox wb = WhiteBox.getWhiteBox();
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder("-Xlog:os+container=trace", "-version");
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+
+        if (wb.isContainerized()) {
+            System.out.println("Inside a cgroup, testing...");
+            isContainer(output);
+        } else {
+            System.out.println("Not in a cgroup, testing...");
+            isNotContainer(output);
+        }
+    }
+}