Re: [libvirt] PATCH: 4/5: Locking in the LXC driver
On Fri, Oct 17, 2008 at 07:53:06AM -0700, Dan Smith wrote:
DB> @@ -104,8 +117,12 @@ static virDomainPtr lxcDomainLookupByID(
DB> int id)
DB> {
DB> lxc_driver_t *driver = (lxc_driver_t *)conn->privateData;
DB> - virDomainObjPtr vm = virDomainFindByID(&driver->domains, id);
DB> + virDomainObjPtr vm;
DB> virDomainPtr dom;
DB> +
DB> + lxcDriverLock(driver);
DB> + vm = virDomainFindByID(&driver->domains, id);
DB> + lxcDriverUnlock(driver);
DB> if (!vm) {
DB> lxcError(conn, NULL, VIR_ERR_NO_DOMAIN, NULL);
DB> @@ -117,6 +134,7 @@ static virDomainPtr lxcDomainLookupByID(
dom-> id = vm->def->id;
DB> }
DB> + virDomainUnlock(vm);
DB> return dom;
DB> }
Can you explain why you're unlocking the vm in all of these functions
without first the corresponding lock operation?
You didn't read the previous mail in this sequence :-P
http://www.redhat.com/archives/libvir-list/2008-October/msg00419.html
[quote]
* Domain lookup methods
virDomainObjPtr virDomainFindByID(const virDomainObjListPtr doms,
int id);
virDomainObjPtr virDomainFindByUUID(const virDomainObjListPtr doms,
const unsigned char *uuid);
virDomainObjPtr virDomainFindByName(const virDomainObjListPtr doms,
const char *name);
The driver must hold its global lock to protect the virDomainObjListPtr
object. The returned virDomainObjPtr instance will be locked at which
point the driver can optionall release its global lock
[/quote]
DB> @@ -1091,17 +1230,20 @@ static int lxcShutdown(void)
DB> */
DB> static int
DB> lxcActive(void) {
DB> - unsigned int i;
DB> + unsigned int i, active = 0;
DB> if (lxc_driver == NULL)
DB> return(0);
DB> - for (i = 0 ; i < lxc_driver->domains.count ; i++)
DB> + lxcDriverLock(lxc_driver);
DB> + for (i = 0 ; i < lxc_driver->domains.count ; i++) {
DB> + virDomainLock(lxc_driver->domains.objs[i]);
DB> if (virDomainIsActive(lxc_driver->domains.objs[i]))
DB> - return 1;
DB> + active = 1;
DB> + virDomainUnlock(lxc_driver->domains.objs[i]);
DB> + }
DB> - /* Otherwise we're happy to deal with a shutdown */
DB> - return 0;
DB> + return active;
DB> }
It looks to me like you're taking the driver lock and not releasing it
on exit.
Yes, well spotted.
Daniel
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