[libvirt] [PATCH 3/9] lxc: Use atomic ops for driver->nactive
Daniel P. Berrange
berrange at redhat.com
Thu Jul 18 10:12:59 UTC 2013
On Wed, Jul 17, 2013 at 03:04:20PM +0200, Michal Privoznik wrote:
> ---
> src/lxc/lxc_conf.h | 2 +-
> src/lxc/lxc_process.c | 10 ++++------
> 2 files changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/src/lxc/lxc_conf.h b/src/lxc/lxc_conf.h
> index 6ca6198..f9a3e53 100644
> --- a/src/lxc/lxc_conf.h
> +++ b/src/lxc/lxc_conf.h
> @@ -77,7 +77,7 @@ struct _virLXCDriver {
>
> virSysinfoDefPtr hostsysinfo;
>
> - size_t nactive;
> + unsigned int nactive;
>
> virStateInhibitCallback inhibitCallback;
> void *inhibitOpaque;
> diff --git a/src/lxc/lxc_process.c b/src/lxc/lxc_process.c
> index 1024576..4b83729 100644
> --- a/src/lxc/lxc_process.c
> +++ b/src/lxc/lxc_process.c
> @@ -48,6 +48,7 @@
> #include "lxc_hostdev.h"
> #include "virhook.h"
> #include "virstring.h"
> +#include "viratomic.h"
>
> #define VIR_FROM_THIS VIR_FROM_LXC
>
> @@ -256,8 +257,7 @@ static void virLXCProcessCleanup(virLXCDriverPtr driver,
> vm->pid = -1;
> vm->def->id = -1;
>
> - driver->nactive--;
> - if (!driver->nactive && driver->inhibitCallback)
> + if (virAtomicIntDecAndTest(&driver->nactive) && driver->inhibitCallback)
> driver->inhibitCallback(false, driver->inhibitOpaque);
>
> virLXCDomainReAttachHostDevices(driver, vm->def);
> @@ -1273,9 +1273,8 @@ int virLXCProcessStart(virConnectPtr conn,
> virDomainObjSetState(vm, VIR_DOMAIN_RUNNING, reason);
> priv->doneStopEvent = false;
>
> - if (!driver->nactive && driver->inhibitCallback)
> + if (virAtomicIntInc(&driver->nactive) && driver->inhibitCallback)
> driver->inhibitCallback(true, driver->inhibitOpaque);
> - driver->nactive++;
I think you need virAtomicIntInc() == 1 here, otherwise this will
execute on every single VM start, instead of only the first.
>
> if (lxcContainerWaitForContinue(handshakefds[0]) < 0) {
> char out[1024];
> @@ -1458,9 +1457,8 @@ virLXCProcessReconnectDomain(virDomainObjPtr vm,
> virDomainObjSetState(vm, VIR_DOMAIN_RUNNING,
> VIR_DOMAIN_RUNNING_UNKNOWN);
>
> - if (!driver->nactive && driver->inhibitCallback)
> + if (virAtomicIntInc(&driver->nactive) && driver->inhibitCallback)
> driver->inhibitCallback(true, driver->inhibitOpaque);
> - driver->nactive++;
Again here, we want == 1.
virAtomicIntInc() == 1, is the pattern the QEMU driver uses for this
code.
Daniel
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