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[libvirt] [PATCH 4/5] rpc: avoid crashing in pre-exec if no workers are present

Daniel P. Berrangé posted 5 patches 7 years, 2 months ago
[libvirt] [PATCH 4/5] rpc: avoid crashing in pre-exec if no workers are present
Posted by Daniel P. Berrangé 7 years, 2 months ago 
If max_workers is set to zero, then the worker thread pool won't be
created, so when serializing state for pre-exec we must set various
parameters to zero.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 src/rpc/virnetserver.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/rpc/virnetserver.c b/src/rpc/virnetserver.c
index 7a1376bf49..3ce21a8f53 100644
--- a/src/rpc/virnetserver.c
+++ b/src/rpc/virnetserver.c
@@ -580,18 +580,21 @@ virJSONValuePtr virNetServerPreExecRestart(virNetServerPtr srv)
         goto error;
 
     if (virJSONValueObjectAppendNumberUint(object, "min_workers",
+                                           srv->workers == NULL ? 0 :
                                            virThreadPoolGetMinWorkers(srv->workers)) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("Cannot set min_workers data in JSON document"));
         goto error;
     }
     if (virJSONValueObjectAppendNumberUint(object, "max_workers",
+                                           srv->workers == NULL ? 0 :
                                            virThreadPoolGetMaxWorkers(srv->workers)) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("Cannot set max_workers data in JSON document"));
         goto error;
     }
     if (virJSONValueObjectAppendNumberUint(object, "priority_workers",
+                                           srv->workers == NULL ? 0 :
                                            virThreadPoolGetPriorityWorkers(srv->workers)) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("Cannot set priority_workers data in JSON document"));
-- 
2.14.3

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Re: [libvirt] [PATCH 4/5] rpc: avoid crashing in pre-exec if no workers are present
Posted by John Ferlan 7 years, 2 months ago 

On 03/06/2018 12:58 PM, Daniel P. Berrangé wrote:
> If max_workers is set to zero, then the worker thread pool won't be
> created, so when serializing state for pre-exec we must set various
> parameters to zero.
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  src/rpc/virnetserver.c | 3 +++
>  1 file changed, 3 insertions(+)
> 

Alternatively, the various virThreadPoolGet* API's could check :

    if (!pool)
        return 0;

and we don't run into the same problem for other callers for all the API's.

This works, but for this limited case of data being fetched.

It'd be a weak R-b at best.

John

> diff --git a/src/rpc/virnetserver.c b/src/rpc/virnetserver.c
> index 7a1376bf49..3ce21a8f53 100644
> --- a/src/rpc/virnetserver.c
> +++ b/src/rpc/virnetserver.c
> @@ -580,18 +580,21 @@ virJSONValuePtr virNetServerPreExecRestart(virNetServerPtr srv)
>          goto error;
>  
>      if (virJSONValueObjectAppendNumberUint(object, "min_workers",
> +                                           srv->workers == NULL ? 0 :
>                                             virThreadPoolGetMinWorkers(srv->workers)) < 0) {
>          virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                         _("Cannot set min_workers data in JSON document"));
>          goto error;
>      }
>      if (virJSONValueObjectAppendNumberUint(object, "max_workers",
> +                                           srv->workers == NULL ? 0 :
>                                             virThreadPoolGetMaxWorkers(srv->workers)) < 0) {
>          virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                         _("Cannot set max_workers data in JSON document"));
>          goto error;
>      }
>      if (virJSONValueObjectAppendNumberUint(object, "priority_workers",
> +                                           srv->workers == NULL ? 0 :
>                                             virThreadPoolGetPriorityWorkers(srv->workers)) < 0) {
>          virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                         _("Cannot set priority_workers data in JSON document"));
> 

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Re: [libvirt] [PATCH 4/5] rpc: avoid crashing in pre-exec if no workers are present
Posted by Daniel P. Berrangé 7 years, 2 months ago 
On Wed, Mar 07, 2018 at 06:50:09PM -0500, John Ferlan wrote:
> 
> 
> On 03/06/2018 12:58 PM, Daniel P. Berrangé wrote:
> > If max_workers is set to zero, then the worker thread pool won't be
> > created, so when serializing state for pre-exec we must set various
> > parameters to zero.
> > 
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> > ---
> >  src/rpc/virnetserver.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> 
> Alternatively, the various virThreadPoolGet* API's could check :
> 
>     if (!pool)
>         return 0;
> 
> and we don't run into the same problem for other callers for all the API's.

My general opinion is that code should never knowingly pass NULL into
object methods, so I prefer to handle this in callers.

> 
> This works, but for this limited case of data being fetched.
> 
> It'd be a weak R-b at best.
> 
> John
> 
> > diff --git a/src/rpc/virnetserver.c b/src/rpc/virnetserver.c
> > index 7a1376bf49..3ce21a8f53 100644
> > --- a/src/rpc/virnetserver.c
> > +++ b/src/rpc/virnetserver.c
> > @@ -580,18 +580,21 @@ virJSONValuePtr virNetServerPreExecRestart(virNetServerPtr srv)
> >          goto error;
> >  
> >      if (virJSONValueObjectAppendNumberUint(object, "min_workers",
> > +                                           srv->workers == NULL ? 0 :
> >                                             virThreadPoolGetMinWorkers(srv->workers)) < 0) {
> >          virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> >                         _("Cannot set min_workers data in JSON document"));
> >          goto error;
> >      }
> >      if (virJSONValueObjectAppendNumberUint(object, "max_workers",
> > +                                           srv->workers == NULL ? 0 :
> >                                             virThreadPoolGetMaxWorkers(srv->workers)) < 0) {
> >          virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> >                         _("Cannot set max_workers data in JSON document"));
> >          goto error;
> >      }
> >      if (virJSONValueObjectAppendNumberUint(object, "priority_workers",
> > +                                           srv->workers == NULL ? 0 :
> >                                             virThreadPoolGetPriorityWorkers(srv->workers)) < 0) {
> >          virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> >                         _("Cannot set priority_workers data in JSON document"));
> > 

Regards,
Daniel
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Re: [libvirt] [PATCH 4/5] rpc: avoid crashing in pre-exec if no workers are present
Posted by Jim Fehlig 7 years, 2 months ago 
On 03/06/2018 10:58 AM, Daniel P. Berrangé wrote:
> If max_workers is set to zero, then the worker thread pool won't be
> created, so when serializing state for pre-exec we must set various
> parameters to zero.
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>   src/rpc/virnetserver.c | 3 +++
>   1 file changed, 3 insertions(+)

Reviewed-by: Jim Fehlig <jfehlig@suse.com>

Regards,
Jim

> 
> diff --git a/src/rpc/virnetserver.c b/src/rpc/virnetserver.c
> index 7a1376bf49..3ce21a8f53 100644
> --- a/src/rpc/virnetserver.c
> +++ b/src/rpc/virnetserver.c
> @@ -580,18 +580,21 @@ virJSONValuePtr virNetServerPreExecRestart(virNetServerPtr srv)
>           goto error;
>   
>       if (virJSONValueObjectAppendNumberUint(object, "min_workers",
> +                                           srv->workers == NULL ? 0 :
>                                              virThreadPoolGetMinWorkers(srv->workers)) < 0) {
>           virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                          _("Cannot set min_workers data in JSON document"));
>           goto error;
>       }
>       if (virJSONValueObjectAppendNumberUint(object, "max_workers",
> +                                           srv->workers == NULL ? 0 :
>                                              virThreadPoolGetMaxWorkers(srv->workers)) < 0) {
>           virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                          _("Cannot set max_workers data in JSON document"));
>           goto error;
>       }
>       if (virJSONValueObjectAppendNumberUint(object, "priority_workers",
> +                                           srv->workers == NULL ? 0 :
>                                              virThreadPoolGetPriorityWorkers(srv->workers)) < 0) {
>           virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                          _("Cannot set priority_workers data in JSON document"));
> 

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