On 03/09/18 18:01, Wei Liu wrote: > On Mon, Sep 03, 2018 at 05:58:02PM +0100, Andrew Cooper wrote: >> On 03/09/18 17:54, Wei Liu wrote: >>> On Mon, Sep 03, 2018 at 03:46:57PM +0100, Andrew Cooper wrote: >>>> This is the first step in making the destroy path idepotent, and using it >>>> in >>> "idempotent". >>> >>>> place of the ad-hoc cleanup paths in the create path. >>>> >>>> To begin with, the trivial free operations are broken out. The rest of the >>>> cleanup code will be moved as it is demonstrated (or made) to be >>>> idempotent. >>>> >>>> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com> >>>> --- >>>> CC: Jan Beulich <jbeul...@suse.com> >>>> CC: Wei Liu <wei.l...@citrix.com> >>>> CC: Roger Pau Monné <roger....@citrix.com> >>>> CC: Stefano Stabellini <sstabell...@kernel.org> >>>> CC: Julien Grall <julien.gr...@arm.com> >>>> --- >>>> xen/common/domain.c | 29 ++++++++++++++++++++++------- >>>> 1 file changed, 22 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/xen/common/domain.c b/xen/common/domain.c >>>> index 43ab926..2253c2d 100644 >>>> --- a/xen/common/domain.c >>>> +++ b/xen/common/domain.c >>>> @@ -260,6 +260,23 @@ static int __init parse_extra_guest_irqs(const char >>>> *s) >>>> } >>>> custom_param("extra_guest_irqs", parse_extra_guest_irqs); >>>> >>>> +/* >>>> + * Destroy a domain once all references to it have been dropped. Used >>>> either >>>> + * from the RCU path, or from the domain_create() error path before the >>>> domain >>>> + * is inserted into the domlist. >>>> + */ >>>> +static void __domain_destroy(struct domain *d) >>>> +{ >>>> + BUG_ON(!d->is_dying); >>>> + BUG_ON(atomic_read(&d->refcnt) != DOMAIN_DESTROYED); >>>> + >>>> + xfree(d->pbuf); >>> With this changed to XFREE here: >> This is the one place where it doesn't matter. d goes fully out of >> scope before the end of this function. > That's fair enough. > >>> Reviewed-by: Wei Liu <wei.l...@citrix.com> >>> >>>> + >>>> + free_cpumask_var(d->dirty_cpumask); >>> On making things idempotent: this function seems to be a candidate. >> I don't understand. One implementation is xfree() under the hood, and >> the other is a no-op because no allocation took place. > I mean it would probably be useful to make free_cpumask_var idempotent > by using XFREE so multiple calls to it will not free dangling pointer.
Ah - that's complicated because of the (lack of) indirection of the parameter. There is FREE_CPUMASK_VAR() which DTRT, but see above for why it isn't used. (There is a similar FREE_XENHEAP_PAGE helper). ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel