[libvirt] [PATCHv5 14/19] Util: Add function for checking if monitor is running

[Wang, Huaqiang]

> -----Original Message-----
> From: John Ferlan [mailto:jferlan at redhat.com]
> Sent: Thursday, October 11, 2018 4:58 AM
> To: Wang, Huaqiang <huaqiang.wang at intel.com>; libvir-list at redhat.com
> Cc: Feng, Shaohe <shaohe.feng at intel.com>; Niu, Bing <bing.niu at intel.com>;
> Ding, Jian-feng <jian-feng.ding at intel.com>; Zang, Rui <rui.zang at intel.com>
> Subject: Re: [libvirt] [PATCHv5 14/19] Util: Add function for checking if monitor
> is running
> 
> 
> 
> On 10/9/18 6:30 AM, Wang Huaqiang wrote:
> > Check monitor status by checking the PIDs are in file 'task'
> > or not.
> >
> > Signed-off-by: Wang Huaqiang <huaqiang.wang at intel.com>
> > ---
> >  src/libvirt_private.syms |  1 +
> >  src/util/virresctrl.c    | 84
> +++++++++++++++++++++++++++++++++++++++++++++++-
> >  src/util/virresctrl.h    |  4 +++
> >  3 files changed, 88 insertions(+), 1 deletion(-)
> >
> > diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index
> > 4b22ed4..c90e48a 100644
> > --- a/src/libvirt_private.syms
> > +++ b/src/libvirt_private.syms
> > @@ -2686,6 +2686,7 @@ virResctrlMonitorDeterminePath;
> > virResctrlMonitorGetCacheLevel;  virResctrlMonitorGetCacheOccupancy;
> >  virResctrlMonitorGetID;
> > +virResctrlMonitorIsRunning;
> >  virResctrlMonitorNew;
> >  virResctrlMonitorRemove;
> >  virResctrlMonitorSetCacheLevel;
> > diff --git a/src/util/virresctrl.c b/src/util/virresctrl.c index
> > 41e8d48..67dfbb8 100644
> > --- a/src/util/virresctrl.c
> > +++ b/src/util/virresctrl.c
> > @@ -364,6 +364,9 @@ struct _virResctrlMonitor {
> >      char *path;
> >      /* Boolean flag for default monitor */
> >      bool default_monitor;
> > +    /* Tracking the tasks' PID associated with this monitor */
> > +    pid_t *pids;
> > +    size_t npids;
> >      /* The cache 'level', special for cache monitor */
> >      unsigned int cache_level;
> >  };
> > @@ -425,6 +428,7 @@ virResctrlMonitorDispose(void *obj)
> >      virObjectUnref(monitor->alloc);
> >      VIR_FREE(monitor->id);
> >      VIR_FREE(monitor->path);
> > +    VIR_FREE(monitor->pids);
> >  }
> >
> >
> > @@ -2491,7 +2495,13 @@ int
> >  virResctrlMonitorAddPID(virResctrlMonitorPtr monitor,
> >                          pid_t pid)
> >  {
> > -    return virResctrlAddPID(monitor->path, pid);
> > +    if (virResctrlAddPID(monitor->path, pid) < 0)
> > +        return -1;
> > +
> > +    if (VIR_APPEND_ELEMENT(monitor->pids, monitor->npids, pid) < 0)
> > +        return -1;
> > +
> > +    return 0;
> >  }
> >
> >
> > @@ -2762,3 +2772,75 @@
> > virResctrlMonitorSetDefault(virResctrlMonitorPtr monitor)  {
> >      monitor->default_monitor = true;
> >  }
> > +
> > +
> > +static int
> > +virResctrlPIDCompare(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;
> > +
> > +    if (!monitor->path)
> > +        return false;
> > +
> > +    if (monitor->npids == 0)
> > +        return false;
> > +
> > +    rv = virFileReadValueString(&pidstr, "%s/tasks", monitor->path);
> > +    if (rv == -2)
> > +        virReportError(VIR_ERR_INTERNAL_ERROR,
> > +                       _("Task file '%s/tasks' does not exist"),
> > +                       monitor->path);
> > +    if (rv < 0)
> > +        goto cleanup;
> > +
> > +    /* no PID in task file */
> > +    if (!*pidstr)
> > +        goto cleanup;
> > +
> > +    spids = virStringSplitCount(pidstr, "\n", 0, &nspids);
> > +    if (nspids != monitor->npids)
> > +        return false;
> 
> This will cause a leak...  "goto cleanup;"

My bad. Will be corrected.

> 
> > +
> > +    for (i = 0; i < nspids; i++) {
> > +        unsigned int val = 0;
> > +        pid_t pid = 0;
> > +
> > +        if (virStrToLong_uip(spids[i], NULL, 0, &val) < 0)
> > +            goto cleanup;
> > +
> > +        pid = (pid_t)val;
> > +
> > +        if (VIR_APPEND_ELEMENT(pids, npids, pid) < 0)
> > +            goto cleanup;
> > +    }
> > +
> > +    qsort(pids, npids, sizeof(pid_t), virResctrlPIDCompare);
> > +    qsort(monitor->pids, monitor->npids, sizeof(pid_t),
> > + virResctrlPIDCompare);
> > +
> > +    for (i = 0; i < monitor->npids; i++) {
> > +        if (monitor->pids[i] != pids[i])
> > +            goto cleanup;
> > +    }
> > +
> > +    ret = true;
> > + cleanup:
> 
> NB: Any place where you get here without an error message, but w/ ret = false
> may cause "issues" for the caller especially since some of the ways to get here
> w/ @false do set an error message.

Got.
Will add some comments for each return and each 'goto cleanup', and will
refine the error message.

> 
> John
> 


Thanks for review.
Huaqiang


> > +    virStringListFree(spids);
> > +    VIR_FREE(pids);
> > +    VIR_FREE(pidstr);
> > +
> > +    return ret;
> > +}
> > diff --git a/src/util/virresctrl.h b/src/util/virresctrl.h index
> > 371df8a..c5794cb 100644
> > --- a/src/util/virresctrl.h
> > +++ b/src/util/virresctrl.h
> > @@ -230,4 +230,8 @@
> virResctrlMonitorGetCacheOccupancy(virResctrlMonitorPtr monitor,
> >                                     unsigned int **bankcaches);  void
> > virResctrlMonitorSetDefault(virResctrlMonitorPtr monitor);
> > +
> > +bool
> > +virResctrlMonitorIsRunning(virResctrlMonitorPtr monitor);
> > +
> >  #endif /*  __VIR_RESCTRL_H__ */
> >