The data size of PCB for IPv4 increased because of the merge of
struct in6pcb. The change decreases the size to the original size by
separating struct inpcb (again). struct in4pcb and in6pcb that embed
struct inpcb are introduced.
Even after the separation, users don't need to realize the separation
and only have to use some macros to access dedicated data. For example,
inp->inp_laddr is now accessed through in4p_laddr(inp).
Data structures of network protocol control blocks (PCBs), i.e.,
struct inpcb, in6pcb and inpcb_hdr, are not organized well. Users of
the data structures have to handle them separately and thus the code
is cluttered and duplicated.
The commit integrates the data structures into one, struct inpcb. As a
result, users of PCBs only have to handle just one data structure, so
the code becomes simple.
One drawback is that the data size of PCB for IPv4 increases by 40 bytes
(from 248 bytes to 288 bytes).
Some routing daemons require such routing message to keep coherency.
If we want to let kernel send such message, set net.inet.icmp.dynamic_rt_msg=1
for IPv4, net.inet6.icmp6.dynamic_rt_msg=1 for IPv6.
Default(=0) is the same as before, that is, not send such routing message.
These comments are added with IFNET_LOCK by in_pcb.c:r1.180 and
in6_pcb.c:r1.162. And then, IFNET_LOCK codes are removed in
in_pcb.c:r1.183 and in6_pcb.c:r1.166, however the comments have
remained.
You should always be able to bind to the unspecified address even if
no addresses have been configured on any interface.
For example, a DHCP client could be started before the loopback interface
has been fully configured.
The IFNET_LOCK was added to avoid data races on if_flags for IFF_ALLMULTI.
Unfortunatetly it caused a deadlock instead. A known scenario causing a
deadlock is to occur the following two operations concurrently: (a) a removal of
an IP adddres assigned to an interface and (b) a manipulation of multicast
groups to the interface. The resource dependency graph is like this:
softnet_lock => IFNET_LOCK => psref_target_destroy => softint => softnet_lock
Thanks to the previous commit that avoids data races on if_flags for
IFF_ALLMULTI by another approach, we can remove IFNET_LOCK and defuse the
deadlock.
PR kern/54189
ipsec4_get_policy and ipsec6_get_policy
ipsec4_delete_pcbpolicy and ipsec6_delete_pcbpolicy
The already-existing ipsec_get_policy() function is inlined in the new
one.
2) Change the IP_RECVPKTINFO option to control the generation of
IP_PKTINFO control messages, the way it's done in Solaris.
3) Remove the superfluous IP_RECVPKTINFO control message.
4) Change the IP_PKTINFO option to do different things depending on
the parameter it's supplied with:
- If it's sizeof(int), assume it's being used as in Linux:
- If it's non-zero, turn on the IP_RECVPKTINFO option.
- If it's zero, turn off the IP_RECVPKTINFO option.
- If it's sizeof(struct in_pktinfo), assume it's being used as in
Solaris, to set a default for the source interface and/or
source address for outgoing packets on the socket.
5) Return what Linux or Solaris compatible code expects, depending
on data size, and just added a fallback to a Linux (and current NetBSD)
compatible value if the size is unknown (as it is now), or,
in the future, if the calling application specifies a receiving
buffer that doesn't match either data item.
From: Tom Ivar Helbekkmo
The source address or output interface can be specified by adding IP_PKTINFO
to the control part of the message on a SOCK_DGRAM or SOCK_RAW socket.
Reviewed by ozaki-r@ and christos@. thanks.
See the following descriptions for details.
Proposed on tech-kern and tech-net
Overview
--------
We protect the routing table with a rwock and protect
rtcaches with another rwlock. Each rtentry is protected
from being freed or updated via reference counting and psref.
Global rwlocks
--------------
There are two rwlocks; one for the routing table (rt_lock) and
the other for rtcaches (rtcache_lock). rtcache_lock covers
all existing rtcaches; there may have room for optimizations
(future work).
The locking order is rtcache_lock first and rt_lock is next.
rtentry references
------------------
References to an rtentry is managed with reference counting
and psref. Either of the two mechanisms is used depending on
where a rtentry is obtained. Reference counting is used when
we obtain a rtentry from the routing table directly via
rtalloc1 and rtrequest{,1} while psref is used when we obtain
a rtentry from a rtcache via rtcache_* APIs. In both cases,
a caller can sleep/block with holding an obtained rtentry.
The reasons why we use two different mechanisms are (i) only
using reference counting hurts the performance due to atomic
instructions (rtcache case) (ii) ease of implementation;
applying psref to APIs such rtaloc1 and rtrequest{,1} requires
additional works (adding a local variable and an argument).
We will finally migrate to use only psref but we can do it
when we have a lockless routing table alternative.
Reference counting for rtentry
------------------------------
rt_refcnt now doesn't count permanent references such as for
rt_timers and rtcaches, instead it is used only for temporal
references when obtaining a rtentry via rtalloc1 and rtrequest{,1}.
We can do so because destroying a rtentry always involves
removing references of rt_timers and rtcaches to the rtentry
and we don't need to track such references. This also makes
it easy to wait for readers to release references on deleting
or updating a rtentry, i.e., we can simply wait until the
reference counter is 0 or 1. (If there are permanent references
the counter can be arbitrary.)
rt_ref increments a reference counter of a rtentry and rt_unref
decrements it. rt_ref is called inside APIs (rtalloc1 and
rtrequest{,1} so users don't need to care about it while
users must call rt_unref to an obtained rtentry after using it.
rtfree is removed and we use rt_unref and rt_free instead.
rt_unref now just decrements the counter of a given rtentry
and rt_free just tries to destroy a given rtentry.
See the next section for destructions of rtentries by rt_free.
Destructions of rtentries
-------------------------
We destroy a rtentry only when we call rtrequst{,1}(RTM_DELETE);
the original implementation can destroy in any rtfree where it's
the last reference. If we use reference counting or psref, it's
easy to understand if the place that a rtentry is destroyed is
fixed.
rt_free waits for references to a given rtentry to be released
before actually destroying the rtentry. rt_free uses a condition
variable (cv_wait) (and psref_target_destroy for psref) to wait.
Unfortunately rtrequst{,1}(RTM_DELETE) can be called in softint
that we cannot use cv_wait. In that case, we have to defer the
destruction to a workqueue.
rtentry#rt_cv, rtentry#rt_psref and global variables
(see rt_free_global) are added to conduct the procedure.
Updates of rtentries
--------------------
One difficulty to use refcnt/psref instead of rwlock for rtentry
is updates of rtentries. We need an additional mechanism to
prevent readers from seeing inconsistency of a rtentry being
updated.
We introduce RTF_UPDATING flag to rtentries that are updating.
While the flag is set to a rtentry, users cannot acquire the
rtentry. By doing so, we avoid users to see inconsistent
rtentries.
There are two options when a user tries to acquire a rtentry
with the RTF_UPDATING flag; if a user runs in softint context
the user fails to acquire a rtentry (NULL is returned).
Otherwise a user waits until the update completes by waiting
on cv.
The procedure of a updater is simpler to destruction of
a rtentry. Wait on cv (and psref) and after all readers left,
proceed with the update.
Global variables (see rt_update_global) are added to conduct
the procedure.
Currently we apply the mechanism to only RTM_CHANGE in
rtsock.c. We would have to apply other codes. See
"Known issues" section.
psref for rtentry
-----------------
When we obtain a rtentry from a rtcache via rtcache_* APIs,
psref is used to reference to the rtentry.
rtcache_ref acquires a reference to a rtentry with psref
and rtcache_unref releases the reference after using it.
rtcache_ref is called inside rtcache_* APIs and users don't
need to take care of it while users must call rtcache_unref
to release the reference.
struct psref and int bound that is needed for psref is
embedded into struct route. By doing so we don't need to
add local variables and additional argument to APIs.
However this adds another constraint to psref other than
reference counting one's; holding a reference of an rtentry
via a rtcache is allowed by just one caller at the same time.
So we must not acquire a rtentry via a rtcache twice and
avoid a recursive use of a rtcache. And also a rtcache must
be arranged to be used by a LWP/softint at the same time
somehow. For IP forwarding case, we have per-CPU rtcaches
used in softint so the constraint is guaranteed. For a h
rtcache of a PCB case, the constraint is guaranteed by the
solock of each PCB. Any other cases (pf, ipf, stf and ipsec)
are currently guaranteed by only the existence of the global
locks (softnet_lock and/or KERNEL_LOCK). If we've found the
cases that we cannot guarantee the constraint, we would need
to introduce other rtcache APIs that use simple reference
counting.
psref of rtcache is created with IPL_SOFTNET and so rtcache
shouldn't used at an IPL higher than IPL_SOFTNET.
Note that rtcache_free is used to invalidate a given rtcache.
We don't need another care by my change; just keep them as
they are.
Performance impact
------------------
When NET_MPSAFE is disabled the performance drop is 3% while
when it's enabled the drop is increased to 11%. The difference
comes from that currently we don't take any global locks and
don't use psref if NET_MPSAFE is disabled.
We can optimize the performance of the case of NET_MPSAFE
on by reducing lookups of rtcache that uses psref;
currently we do two lookups but we should be able to trim
one of two. This is a future work.
Known issues
------------
There are two known issues to be solved; one is that
a caller of rtrequest(RTM_ADD) may change rtentry (see rtinit).
We need to prevent new references during the update. Or
we may be able to remove the code (perhaps, need more
investigations).
The other is rtredirect that updates a rtentry. We need
to apply our update mechanism, however it's not easy because
rtredirect is called in softint and we cannot apply our
mechanism simply. One solution is to defer rtredirect to
a workqueue but it requires some code restructuring.
In the MP-safe world, a rtentry stemming from a rtcache can be freed at any
points. So we need to protect rtentries somehow say by reference couting or
passive references. Regardless of the method, we need to call some release
function of a rtentry after using it.
The change adds a new function rtcache_unref to release a rtentry. At this
point, this function does nothing because for now we don't add a reference
to a rtentry when we get one from a rtcache. We will add something useful
in a further commit.
This change is a part of changes for MP-safe routing table. It is separated
to avoid one big change that makes difficult to debug by bisecting.
This change makes struct ifaddr and its variants (in_ifaddr and in6_ifaddr)
MP-safe by using pserialize and psref. At this moment, pserialize_perform
and psref_target_destroy are disabled because (1) we don't need them
because of softnet_lock (2) they cause a deadlock because of softnet_lock.
So we'll enable them when we remove softnet_lock in the future.
Note that we leave the old list just in case; it seems there are some
kvm(3) users accessing the list. We can remove it later if we confirmed
nobody does actually.
The motivation is the same as the mbuf's rcvif case; avoid having a pointer
of an ifnet object in ip_moptions and ip6_moptions, which is not MP-safe.
ip_moptions and ip6_moptions can be stored in a PCB for inet or inet6
that's life time is different from ifnet one and so an ifnet object can be
disappeared anytime we get it via them. Thus we need to look up an ifnet
object by if_index every time for safe.
converting protocol user requests to accept sockaddr instead of mbufs.
remove tcp_input copy in to mbuf from sockaddr and just copy to sockaddr
to make it possible for the transitional functions to go away.
no version bump since these functions only existed for a short time and
were commented as adapters (they appeared in 7.99.15).
nam parameter type from buf * to sockaddr *.
final commit for parameter type changes to protocol user requests
* bump kernel version to 7.99.15 for parameter type changes to pr_{send,connect}
IN_IFF_DETATCHED to mimic the IPv6 address behaviour.
Add SIOCGIFAFLAG_IN ioctl to retrieve the address flag via the
ifreq structure.
Add IPv4 DAD detection via the ARP methods described in RFC 5227.
Add sysctls net.inet.ip.dad_count and net.inet.arp.debug.
Discussed on tech-net@
pr_{accept,sockname,peername} nam parameter type from mbuf * to sockaddr *.
* retained use of mbuftypes[MT_SONAME] for now.
* bump to netbsd version 7.99.12 for parameter type change.
patch posted to tech-net@ 2015/04/19
* update protocol bind implementations to use/expect sockaddr *
instead of mbuf *
* introduce sockaddr_big struct for storage of addr data passed via
sys_bind; sockaddr_big is of sufficient size and alignment to
accommodate all addr data sizes received.
* modify sys_bind to allocate sockaddr_big instead of using an mbuf.
* bump kernel version to 7.99.9 for change to pr_bind() parameter type.
Patch posted to tech-net@
http://mail-index.netbsd.org/tech-net/2015/03/15/msg005004.html
The choice to use a new structure sockaddr_big has been retained since
changing sockaddr_storage size would lead to unnecessary ABI change. The
use of the new structure does not preclude future work that increases
the size of sockaddr_storage and at that time sockaddr_big may be
trivially replaced.
Tested by mrg@ and myself, discussed with rmind@, posted to tech-net@
(v4 multicast options off v4 mapped v6 socket) on interface destruction. The
code to clean this up in a true v4 socket was moved to its own function
which is now also called in the corresponding place for v6 sockets on
interface destruction.
ozaki-r