svn commit: r333968 - in head/sys: netinet netinet6
Marko Zec
zec at fer.hr
Mon May 21 08:54:23 UTC 2018
On Mon, 21 May 2018 08:34:10 +0000
Matt Macy <mmacy at freebsd.org> wrote:
> Author: mmacy
> Date: Mon May 21 08:34:10 2018
> New Revision: 333968
> URL: https://svnweb.freebsd.org/changeset/base/333968
>
> Log:
> in(6)_mcast: Expand out vnet set / restore macro so that they work
> in a conditional block
> Reported by: zec at fer.hr
>
> Modified:
> head/sys/netinet/in_mcast.c
> head/sys/netinet6/in6_mcast.c
>
> Modified: head/sys/netinet/in_mcast.c
> ==============================================================================
> --- head/sys/netinet/in_mcast.c Mon May 21 07:12:06
> 2018 (r333967) +++ head/sys/netinet/in_mcast.c Mon May
> 21 08:34:10 2018 (r333968) @@ -653,6 +653,7 @@
> inm_release(struct in_multi *inm) {
> struct ifmultiaddr *ifma;
> struct ifnet *ifp;
> + struct vnet *saved_vnet;
>
> CTR2(KTR_IGMPV3, "%s: refcount is %d", __func__,
> inm->inm_refcount); MPASS(inm->inm_refcount == 0);
> @@ -663,14 +664,16 @@ inm_release(struct in_multi *inm)
>
> /* XXX this access is not covered by IF_ADDR_LOCK */
> CTR2(KTR_IGMPV3, "%s: purging ifma %p", __func__, ifma);
> - if (ifp)
> - CURVNET_SET(ifp->if_vnet);
> + if (ifp) {
> + saved_vnet = curvnet;
> + curvnet = ifp->if_vnet;
> + }
Uhmm... please don't do this, for at least two reasons:
1) so far we could identify all VNET context switches by tracking
CURVNET_SET / _RESTORE macros. With this change a non-standard hack is
introduced, opening the door for more alternative / creative variations
to come, thus increasing the entropy
2) CURVNET_* macros provide elementary capability of tracking vnet
recursions, and much more importantly, forgotten or missed context
restores. Your change breaks this tracking chain.
Is there a reason one could not extend struct in_multi with a struct
vnet *inm_vnet entry, populate it on struct in_multi creation, and be
done with all curvnet woes in a clean way?
Marko
> inm_purge(inm);
> free(inm, M_IPMADDR);
>
> if_delmulti_ifma_flags(ifma, 1);
> if (ifp) {
> - CURVNET_RESTORE();
> + curvnet = saved_vnet;
> if_rele(ifp);
> }
> }
> @@ -1666,6 +1669,7 @@ inp_gcmoptions(epoch_context_t ctx)
> struct in_mfilter *imf;
> struct in_multi *inm;
> struct ifnet *ifp;
> + struct vnet *saved_vnet;
> size_t idx, nmships;
>
> imo = __containerof(ctx, struct ip_moptions, imo_epoch_ctx);
> @@ -1677,11 +1681,13 @@ inp_gcmoptions(epoch_context_t ctx)
> imf_leave(imf);
> inm = imo->imo_membership[idx];
> ifp = inm->inm_ifp;
> - if (ifp)
> - CURVNET_SET(ifp->if_vnet);
> + if (ifp) {
> + saved_vnet = curvnet;
> + curvnet = ifp->if_vnet;
> + }
> (void)in_leavegroup(inm, imf);
> if (ifp)
> - CURVNET_RESTORE();
> + curvnet = saved_vnet;
> if (imf)
> imf_purge(imf);
> }
>
> Modified: head/sys/netinet6/in6_mcast.c
> ==============================================================================
> --- head/sys/netinet6/in6_mcast.c Mon May 21 07:12:06
> 2018 (r333967) +++ head/sys/netinet6/in6_mcast.c Mon
> May 21 08:34:10 2018 (r333968) @@ -524,6 +524,7 @@
> in6m_release(struct in6_multi *inm) {
> struct ifmultiaddr *ifma;
> struct ifnet *ifp;
> + struct vnet *saved_vnet;
>
> CTR2(KTR_MLD, "%s: refcount is %d", __func__,
> inm->in6m_refcount);
> @@ -539,14 +540,16 @@ in6m_release(struct in6_multi *inm)
> KASSERT(ifma->ifma_protospec == NULL,
> ("%s: ifma_protospec != NULL", __func__));
>
> - if (ifp)
> - CURVNET_SET(ifp->if_vnet);
> + if (ifp) {
> + saved_vnet = curvnet;
> + curvnet = ifp->if_vnet;
> + }
> in6m_purge(inm);
> free(inm, M_IP6MADDR);
>
> if_delmulti_ifma_flags(ifma, 1);
> if (ifp) {
> - CURVNET_RESTORE();
> + curvnet = saved_vnet;
> if_rele(ifp);
> }
> }
> @@ -1628,6 +1631,7 @@ inp_gcmoptions(epoch_context_t ctx)
> struct in6_mfilter *imf;
> struct in6_multi *inm;
> struct ifnet *ifp;
> + struct vnet *saved_vnet;
> size_t idx, nmships;
>
> imo = __containerof(ctx, struct ip6_moptions,
> imo6_epoch_ctx); @@ -1639,11 +1643,13 @@
> inp_gcmoptions(epoch_context_t ctx) im6f_leave(imf);
> inm = imo->im6o_membership[idx];
> ifp = inm->in6m_ifp;
> - if (ifp)
> - CURVNET_SET(ifp->if_vnet);
> + if (ifp) {
> + saved_vnet = curvnet;
> + curvnet = ifp->if_vnet;
> + }
> (void)in6_leavegroup(inm, imf);
> if (ifp)
> - CURVNET_RESTORE();
> + curvnet = saved_vnet;
> if (imf)
> im6f_purge(imf);
> }
>
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