[libvirt] [PATCHv6 14/18] util: Add function for checking if monitor is running

[Wang Huaqiang]

Check whether monitor is running by checking the monitor's PIDs status.

Monitor is looked as running normally if the vcpu PID list matches with
the content of monitor's 'tasks' file.

Signed-off-by: Wang Huaqiang <huaqiang.wang at intel.com>
---
 src/libvirt_private.syms |   1 +
 src/util/virresctrl.c    | 102 ++++++++++++++++++++++++++++++++++++++++++++++-
 src/util/virresctrl.h    |   3 ++
 3 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 239b979..cbc86ce 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -2684,6 +2684,7 @@ virResctrlMonitorAddPID;
 virResctrlMonitorCreate;
 virResctrlMonitorDeterminePath;
 virResctrlMonitorGetID;
+virResctrlMonitorIsRunning;
 virResctrlMonitorNew;
 virResctrlMonitorRemove;
 virResctrlMonitorSetAlloc;
diff --git a/src/util/virresctrl.c b/src/util/virresctrl.c
index b4b63b6..fa4c05e 100644
--- a/src/util/virresctrl.c
+++ b/src/util/virresctrl.c
@@ -359,6 +359,9 @@ struct _virResctrlMonitor {
     /* libvirt-generated path in /sys/fs/resctrl for this particular
      * monitor */
     char *path;
+    /* Tracking the tasks' PID associated with this monitor */
+    pid_t *pids;
+    size_t npids;
 };
 
 
@@ -418,6 +421,7 @@ virResctrlMonitorDispose(void *obj)
     virObjectUnref(monitor->alloc);
     VIR_FREE(monitor->id);
     VIR_FREE(monitor->path);
+    VIR_FREE(monitor->pids);
 }
 
 
@@ -2537,7 +2541,20 @@ int
 virResctrlMonitorAddPID(virResctrlMonitorPtr monitor,
                         pid_t pid)
 {
-    return virResctrlAddPID(monitor->path, pid);
+    size_t i = 0;
+
+    if (virResctrlAddPID(monitor->path, pid) < 0)
+        return -1;
+
+    for (i = 0; i < monitor->npids; i++) {
+        if (pid == monitor->pids[i])
+            return 0;
+    }
+
+    if (VIR_APPEND_ELEMENT(monitor->pids, monitor->npids, pid) < 0)
+        return -1;
+
+    return 0;
 }
 
 
@@ -2610,3 +2627,86 @@ virResctrlMonitorRemove(virResctrlMonitorPtr monitor)
 
     return ret;
 }
+
+
+static int
+virResctrlPIDSorter(const void *pida, const void *pidb)
+{
+    return *(pid_t*)pida - *(pid_t*)pidb;
+}
+
+
+bool
+virResctrlMonitorIsRunning(virResctrlMonitorPtr monitor)
+{
+    char *pidstr = NULL;
+    char **spids = NULL;
+    size_t nspids = 0;
+    pid_t *pids = NULL;
+    size_t npids = 0;
+    size_t i = 0;
+    int rv = -1;
+    bool ret = false;
+
+    /* path is not determined yet, monitor is not running*/
+    if (!monitor->path)
+        return false;
+
+    /* No vcpu PID filled, regard monitor as not running */
+    if (monitor->npids == 0)
+        return false;
+
+    /* If no 'tasks' file found, underlying resctrl directory is not
+     * ready, regard monitor as not running */
+    rv = virFileReadValueString(&pidstr, "%s/tasks", monitor->path);
+    if (rv < 0)
+        goto cleanup;
+
+    /* no PID in task file, monitor is not running */
+    if (!*pidstr)
+        goto cleanup;
+
+    /* The tracking monitor PID list is not identical to the
+     * list in current resctrl directory. monitor is corrupted,
+     * report error and un-running state */
+    spids = virStringSplitCount(pidstr, "\n", 0, &nspids);
+    if (nspids != monitor->npids) {
+        VIR_ERROR(_("Monitor %s PID list mismatch in length"), monitor->path);
+        goto cleanup;
+    }
+
+    for (i = 0; i < nspids; i++) {
+        unsigned int val = 0;
+        pid_t pid = 0;
+
+        if (virStrToLong_uip(spids[i], NULL, 0, &val) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Monitor %s failed in parse PID list"),
+                           monitor->path);
+            goto cleanup;
+        }
+
+        pid = (pid_t)val;
+
+        if (VIR_APPEND_ELEMENT(pids, npids, pid) < 0)
+            goto cleanup;
+    }
+
+    qsort(pids, npids, sizeof(pid_t), virResctrlPIDSorter);
+    qsort(monitor->pids, monitor->npids, sizeof(pid_t), virResctrlPIDSorter);
+
+    for (i = 0; i < monitor->npids; i++) {
+        if (monitor->pids[i] != pids[i]) {
+            VIR_ERROR(_("Monitor %s PID list corrupted"), monitor->path);
+            goto cleanup;
+        }
+    }
+
+    ret = true;
+ cleanup:
+    virStringListFree(spids);
+    VIR_FREE(pids);
+    VIR_FREE(pidstr);
+
+    return ret;
+}
diff --git a/src/util/virresctrl.h b/src/util/virresctrl.h
index 804d6f5..8d8fdc2 100644
--- a/src/util/virresctrl.h
+++ b/src/util/virresctrl.h
@@ -219,4 +219,7 @@ virResctrlMonitorSetAlloc(virResctrlMonitorPtr monitor,
 
 int
 virResctrlMonitorRemove(virResctrlMonitorPtr monitor);
+
+bool
+virResctrlMonitorIsRunning(virResctrlMonitorPtr monitor);
 #endif /*  __VIR_RESCTRL_H__ */
-- 
2.7.4