On Mon, Jun 18, 2018 at 09:47 AM +0200, Erik Skultety <eskultet@redhat.com> wrote:
On Fri, Jun 15, 2018 at 03:31:34PM +0200, Marc Hartmayer wrote:
On Fri, Jun 15, 2018 at 01:39 PM +0200, Marc Hartmayer <mhartmay@linux.ibm.com> wrote:
If srv->workers is a NULL pointer, as it is the case if there are no workers, then don't try to dereference it.
Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com> Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com> --- src/rpc/virnetserver.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/src/rpc/virnetserver.c b/src/rpc/virnetserver.c index 5ae809e372..be6f610880 100644 --- a/src/rpc/virnetserver.c +++ b/src/rpc/virnetserver.c @@ -933,13 +933,21 @@ virNetServerGetThreadPoolParameters(virNetServerPtr srv, size_t *jobQueueDepth) { virObjectLock(srv); - - *minWorkers = virThreadPoolGetMinWorkers(srv->workers); - *maxWorkers = virThreadPoolGetMaxWorkers(srv->workers); - *freeWorkers = virThreadPoolGetFreeWorkers(srv->workers); - *nWorkers = virThreadPoolGetCurrentWorkers(srv->workers); - *nPrioWorkers = virThreadPoolGetPriorityWorkers(srv->workers); - *jobQueueDepth = virThreadPoolGetJobQueueDepth(srv->workers); + if (srv->workers) { + *minWorkers = virThreadPoolGetMinWorkers(srv->workers); + *maxWorkers = virThreadPoolGetMaxWorkers(srv->workers); + *freeWorkers = virThreadPoolGetFreeWorkers(srv->workers); + *nWorkers = virThreadPoolGetCurrentWorkers(srv->workers); + *nPrioWorkers = virThreadPoolGetPriorityWorkers(srv->workers); + *jobQueueDepth = virThreadPoolGetJobQueueDepth(srv->workers); + } else { + *minWorkers = 0; + *maxWorkers = 0; + *freeWorkers = 0; + *nWorkers = 0; + *nPrioWorkers = 0; + *jobQueueDepth = 0; + }
virObjectUnlock(srv); return 0; -- 2.13.6
After thinking again it probably makes more sense (and the code more beautiful) to initialize the worker pool even for maxworker=0 (within
I don't understand why should we do that. We don't even initialize it for libvirtd server - the implications are clear - you don't have workers, you don't get to process a job.
virNetServerNew) (=> we'll have to adapt virNetServerDispatchNewMessage as well). BTW, there is also a segmentation fault in virThreadPoolSetParameters… And currently it’s not possible to start with maxworkers set to 0 and then increase it via
Do I assume correctly that virNetServerDispatchNewMessage would allocate a new worker if there was a request to process but the threadpool was empty? If so, I don't see a reason to do that, why would anyone want to run with no workers? They don't consume any resources, since they're waiting on a condition. However, any segfaults or deadlocks must be fixed, I'll have a look at the series as is, unless you've got a compelling reason why it's beneficial to run with no workers at all.
Another problem/inconsistency in the current implementation is that if you start with maxworkers=5 and then set the value to 0 via virThreadPoolSetParameters (e.g. 'virt-admin server-threadpool-set --min-workers 0 --max-workers 0 --priority-workers 0 libvirtd') srv->workers still remains a non NULL value and the “thread pool memory struct” still remains allocated and virNetServerDispatchNewMessage will try to request a job… :)
Thanks, Erik
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