[libvirt] [PATCH] qemu: Use atomic ops for driver->nactive

Daniel P. Berrange berrange at redhat.com
Tue Feb 19 14:20:14 UTC 2013


On Tue, Feb 19, 2013 at 02:58:30PM +0100, Jiri Denemark wrote:
> ---
>  src/qemu/qemu_conf.h    |  2 +-
>  src/qemu/qemu_process.c | 13 +++++--------
>  2 files changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
> index b5a3281..a6bd527 100644
> --- a/src/qemu/qemu_conf.h
> +++ b/src/qemu/qemu_conf.h
> @@ -168,7 +168,7 @@ struct _virQEMUDriver {
>      virCgroupPtr cgroup;
>  
>      /* Atomic inc/dec only */
> -    size_t nactive;
> +    unsigned int nactive;
>  
>      /* Immutable pointers. Caller must provide locking */
>      virStateInhibitCallback inhibitCallback;
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 74406a6..b612d72 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -69,6 +69,7 @@
>  #include "virtime.h"
>  #include "virnetdevtap.h"
>  #include "virbitmap.h"
> +#include "viratomic.h"
>  
>  #define VIR_FROM_THIS VIR_FROM_QEMU
>  
> @@ -3300,9 +3301,8 @@ qemuProcessReconnect(void *opaque)
>              goto error;
>      }
>  
> -    if (!driver->nactive && driver->inhibitCallback)
> +    if (virAtomicIntInc(&driver->nactive) == 1 && driver->inhibitCallback)
>          driver->inhibitCallback(true, driver->inhibitOpaque);
> -    driver->nactive++;
>  
>  endjob:
>      if (!qemuDomainObjEndJob(driver, obj))
> @@ -3589,9 +3589,8 @@ int qemuProcessStart(virConnectPtr conn,
>      qemuDomainSetFakeReboot(driver, vm, false);
>      virDomainObjSetState(vm, VIR_DOMAIN_SHUTOFF, VIR_DOMAIN_SHUTOFF_UNKNOWN);
>  
> -    if (!driver->nactive && driver->inhibitCallback)
> +    if (virAtomicIntInc(&driver->nactive) == 1 && driver->inhibitCallback)
>          driver->inhibitCallback(true, driver->inhibitOpaque);
> -    driver->nactive++;
>  
>      /* Run an early hook to set-up missing devices */
>      if (virHookPresent(VIR_HOOK_DRIVER_QEMU)) {
> @@ -4188,8 +4187,7 @@ void qemuProcessStop(virQEMUDriverPtr driver,
>       */
>      vm->def->id = -1;
>  
> -    driver->nactive--;
> -    if (!driver->nactive && driver->inhibitCallback)
> +    if (virAtomicIntDecAndTest(&driver->nactive) && driver->inhibitCallback)
>          driver->inhibitCallback(false, driver->inhibitOpaque);
>  
>      if ((logfile = qemuDomainCreateLog(driver, vm, true)) < 0) {
> @@ -4443,9 +4441,8 @@ int qemuProcessAttach(virConnectPtr conn ATTRIBUTE_UNUSED,
>  
>      vm->def->id = qemuDriverAllocateID(driver);
>  
> -    if (!driver->nactive && driver->inhibitCallback)
> +    if (virAtomicIntInc(&driver->nactive) == 1 && driver->inhibitCallback)
>          driver->inhibitCallback(true, driver->inhibitOpaque);
> -    driver->nactive++;
>  
>      if (virFileMakePath(cfg->logDir) < 0) {
>          virReportSystemError(errno,

ACK

This is something I had done already but lost in a rebase merge :-(

Daniel
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