Commit Graph

395 Commits

Author SHA1 Message Date
Mike Karels
2fdbcbea76 Fix NULL-pointer bug from r361228.
Note that in_pcb_lport and in_pcb_lport_dest can be called with a NULL
local address for IPv6 sockets; handle it.  Found by syzkaller.

Reported by:	cem
MFC after:	1 month
2020-05-19 01:05:13 +00:00
Mike Karels
2510235150 Allow TCP to reuse local port with different destinations
Previously, tcp_connect() would bind a local port before connecting,
forcing the local port to be unique across all outgoing TCP connections
for the address family. Instead, choose a local port after selecting
the destination and the local address, requiring only that the tuple
is unique and does not match a wildcard binding.

Reviewed by:	tuexen (rscheff, rrs previous version)
MFC after:	1 month
Sponsored by:	Forcepoint LLC
Differential Revision:	https://reviews.freebsd.org/D24781
2020-05-18 22:53:12 +00:00
Alexander V. Chernikov
9ac7c6cfed Convert IP/IPv6 forwarding, ICMP processing and IP PCB laddr selection to
the new routing KPI.

Reviewed by:	ae
Differential Revision:	https://reviews.freebsd.org/D24245
2020-04-14 23:06:25 +00:00
Andrew Gallatin
98085bae8c make lacp's use_numa hashing aware of send tags
When I did the use_numa support, I missed the fact that there is
a separate hash function for send tag nic selection. So when
use_numa is enabled, ktls offload does not work properly, as it
does not reliably allocate a send tag on the proper egress nic
since different egress nics are selected for send-tag allocation
and packet transmit. To fix this, this change:

- refectors lacp_select_tx_port_by_hash() and
     lacp_select_tx_port() to make lacp_select_tx_port_by_hash()
     always called by lacp_select_tx_port()

-   pre-shifts flowids to convert them to hashes when calling lacp_select_tx_port_by_hash()

-   adds a numa_domain field to if_snd_tag_alloc_params

-   plumbs the numa domain into places where we allocate send tags

In testing with NIC TLS setup on a NUMA machine, I see thousands
of output errors before the change when enabling
kern.ipc.tls.ifnet.permitted=1. After the change, I see no
errors, and I see the NIC sysctl counters showing active TLS
offload sessions.

Reviewed by:	rrs, hselasky, jhb
Sponsored by:	Netflix
2020-03-09 13:44:51 +00:00
Pawel Biernacki
7029da5c36 Mark more nodes as CTLFLAG_MPSAFE or CTLFLAG_NEEDGIANT (17 of many)
r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.

This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.

Mark all obvious cases as MPSAFE.  All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT

Approved by:	kib (mentor, blanket)
Commented by:	kib, gallatin, melifaro
Differential Revision:	https://reviews.freebsd.org/D23718
2020-02-26 14:26:36 +00:00
Randall Stewart
481be5de9d White space cleanup -- remove trailing tab's or spaces
from any line.

Sponsored by:	Netflix Inc.
2020-02-12 13:31:36 +00:00
Gleb Smirnoff
c1604fe4d2 Make in_pcbladdr() require network epoch entered by its callers. Together
with this widen network epoch coverage up to tcp_connect() and udp_connect().

Revisions from r356974 and up to this revision cover D23187.

Differential Revision:	https://reviews.freebsd.org/D23187
2020-01-22 06:10:41 +00:00
Gleb Smirnoff
5c722e2ad3 The network epoch changes in the TCP stack combined with old r286227,
actually make removal of a PCB not needing ipi_lock in any form.  The
ipi_list_lock is sufficient.
2020-01-22 06:03:45 +00:00
Gleb Smirnoff
6a2954a17d Relax locking requirements for in_pcballoc(). All pcbinfo fields
modified by this function are protected by the PCB list lock that is
acquired inside the function.

This could have been done even before epoch changes, after r286227.
2020-01-22 05:58:29 +00:00
Gleb Smirnoff
2a4bd982d0 Introduce NET_EPOCH_CALL() macro and use it everywhere where we free
data based on the network epoch.   The macro reverses the argument
order of epoch_call(9) - first function, then its argument. NFC
2020-01-15 06:05:20 +00:00
Michael Tuexen
fe1274ee39 Fix race when accepting TCP connections.
When expanding a SYN-cache entry to a socket/inp a two step approach was
taken:
1) The local address was filled in, then the inp was added to the hash
   table.
2) The remote address was filled in and the inp was relocated in the
   hash table.
Before the epoch changes, a write lock was held when this happens and
the code looking up entries was holding a corresponding read lock.
Since the read lock is gone away after the introduction of the
epochs, the half populated inp was found during lookup.
This resulted in processing TCP segments in the context of the wrong
TCP connection.
This patch changes the above procedure in a way that the inp is fully
populated before inserted into the hash table.

Thanks to Paul <devgs@ukr.net> for reporting the issue on the net@
mailing list and for testing the patch!

Reviewed by:		rrs@
MFC after:		1 week
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D22971
2020-01-12 17:52:32 +00:00
Gleb Smirnoff
d797164a86 Since r353292 on input path we are always in network epoch, when
we lookup PCBs.  Thus, do not enter epoch recursively in
in_pcblookup_hash() and in6_pcblookup_hash().  Same applies to
tcp_ctlinput() and tcp6_ctlinput().

This leaves several sysctl(9) handlers that return PCB credentials
unprotected.  Add epoch enter/exit to all of them.

Differential Revision:	https://reviews.freebsd.org/D22197
2019-11-07 20:49:56 +00:00
Gleb Smirnoff
1a49612526 Mechanically convert INP_INFO_RLOCK() to NET_EPOCH_ENTER().
Remove few outdated comments and extraneous assertions.  No
functional change here.
2019-11-07 00:08:34 +00:00
Xin LI
903c4ee6ec Fix !INET build. 2019-08-02 22:43:09 +00:00
Randall Stewart
20abea6663 This adds the third step in getting BBR into the tree. BBR and
an updated rack depend on having access to the new
ratelimit api in this commit.

Sponsored by:	Netflix Inc.
Differential Revision:	https://reviews.freebsd.org/D20953
2019-08-01 14:17:31 +00:00
Hans Petter Selasky
59854ecf55 Convert all IPv4 and IPv6 multicast memberships into using a STAILQ
instead of a linear array.

The multicast memberships for the inpcb structure are protected by a
non-sleepable lock, INP_WLOCK(), which needs to be dropped when
calling the underlying possibly sleeping if_ioctl() method. When using
a linear array to keep track of multicast memberships, the computed
memory location of the multicast filter may suddenly change, due to
concurrent insertion or removal of elements in the linear array. This
in turn leads to various invalid memory access issues and kernel
panics.

To avoid this problem, put all multicast memberships on a STAILQ based
list. Then the memory location of the IPv4 and IPv6 multicast filters
become fixed during their lifetime and use after free and memory leak
issues are easier to track, for example by: vmstat -m | grep multi

All list manipulation has been factored into inline functions
including some macros, to easily allow for a future hash-list
implementation, if needed.

This patch has been tested by pho@ .

Differential Revision: https://reviews.freebsd.org/D20080
Reviewed by:	markj @
MFC after:	1 week
Sponsored by:	Mellanox Technologies
2019-06-25 11:54:41 +00:00
John Baldwin
fb3bc59600 Restructure mbuf send tags to provide stronger guarantees.
- Perform ifp mismatch checks (to determine if a send tag is allocated
  for a different ifp than the one the packet is being output on), in
  ip_output() and ip6_output().  This avoids sending packets with send
  tags to ifnet drivers that don't support send tags.

  Since we are now checking for ifp mismatches before invoking
  if_output, we can now try to allocate a new tag before invoking
  if_output sending the original packet on the new tag if allocation
  succeeds.

  To avoid code duplication for the fragment and unfragmented cases,
  add ip_output_send() and ip6_output_send() as wrappers around
  if_output and nd6_output_ifp, respectively.  All of the logic for
  setting send tags and dealing with send tag-related errors is done
  in these wrapper functions.

  For pseudo interfaces that wrap other network interfaces (vlan and
  lagg), wrapper send tags are now allocated so that ip*_output see
  the wrapper ifp as the ifp in the send tag.  The if_transmit
  routines rewrite the send tags after performing an ifp mismatch
  check.  If an ifp mismatch is detected, the transmit routines fail
  with EAGAIN.

- To provide clearer life cycle management of send tags, especially
  in the presence of vlan and lagg wrapper tags, add a reference count
  to send tags managed via m_snd_tag_ref() and m_snd_tag_rele().
  Provide a helper function (m_snd_tag_init()) for use by drivers
  supporting send tags.  m_snd_tag_init() takes care of the if_ref
  on the ifp meaning that code alloating send tags via if_snd_tag_alloc
  no longer has to manage that manually.  Similarly, m_snd_tag_rele
  drops the refcount on the ifp after invoking if_snd_tag_free when
  the last reference to a send tag is dropped.

  This also closes use after free races if there are pending packets in
  driver tx rings after the socket is closed (e.g. from tcpdrop).

  In order for m_free to work reliably, add a new CSUM_SND_TAG flag in
  csum_flags to indicate 'snd_tag' is set (rather than 'rcvif').
  Drivers now also check this flag instead of checking snd_tag against
  NULL.  This avoids false positive matches when a forwarded packet
  has a non-NULL rcvif that was treated as a send tag.

- cxgbe was relying on snd_tag_free being called when the inp was
  detached so that it could kick the firmware to flush any pending
  work on the flow.  This is because the driver doesn't require ACK
  messages from the firmware for every request, but instead does a
  kind of manual interrupt coalescing by only setting a flag to
  request a completion on a subset of requests.  If all of the
  in-flight requests don't have the flag when the tag is detached from
  the inp, the flow might never return the credits.  The current
  snd_tag_free command issues a flush command to force the credits to
  return.  However, the credit return is what also frees the mbufs,
  and since those mbufs now hold references on the tag, this meant
  that snd_tag_free would never be called.

  To fix, explicitly drop the mbuf's reference on the snd tag when the
  mbuf is queued in the firmware work queue.  This means that once the
  inp's reference on the tag goes away and all in-flight mbufs have
  been queued to the firmware, tag's refcount will drop to zero and
  snd_tag_free will kick in and send the flush request.  Note that we
  need to avoid doing this in the middle of ethofld_tx(), so the
  driver grabs a temporary reference on the tag around that loop to
  defer the free to the end of the function in case it sends the last
  mbuf to the queue after the inp has dropped its reference on the
  tag.

- mlx5 preallocates send tags and was using the ifp pointer even when
  the send tag wasn't in use.  Explicitly use the ifp from other data
  structures instead.

- Sprinkle some assertions in various places to assert that received
  packets don't have a send tag, and that other places that overwrite
  rcvif (e.g. 802.11 transmit) don't clobber a send tag pointer.

Reviewed by:	gallatin, hselasky, rgrimes, ae
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D20117
2019-05-24 22:30:40 +00:00
Andrew Gallatin
50575ce11c Track TCP connection's NUMA domain in the inpcb
Drivers can now pass up numa domain information via the
mbuf numa domain field.  This information is then used
by TCP syncache_socket() to associate that information
with the inpcb. The domain information is then fed back
into transmitted mbufs in ip{6}_output(). This mechanism
is nearly identical to what is done to track RSS hash values
in the inp_flowid.

Follow on changes will use this information for lacp egress
port selection, binding TCP pacers to the appropriate NUMA
domain, etc.

Reviewed by:	markj, kib, slavash, bz, scottl, jtl, tuexen
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D20028
2019-04-25 15:37:28 +00:00
John Baldwin
43b65e3c98 Don't check the inp socket pointer in in_pcboutput_eagain.
Reviewed by:	hps (by saying it was ok to be removed)
MFC after:	1 month
Sponsored by:	Netflix
2019-03-29 19:47:42 +00:00
Andrey V. Elsukov
c7ee62fcd5 In r335015 PCB destroing was made deferred using epoch_call().
But ipsec_delete_pcbpolicy() uses some VNET-virtualized variables,
and thus it needs VNET context, that is missing during gtaskqueue
executing. Use inp_vnet context to set curvnet in in_pcbfree_deferred().

PR:		235684
MFC after:	1 week
2019-02-13 15:46:05 +00:00
Gleb Smirnoff
a68cc38879 Mechanical cleanup of epoch(9) usage in network stack.
- Remove macros that covertly create epoch_tracker on thread stack. Such
  macros a quite unsafe, e.g. will produce a buggy code if same macro is
  used in embedded scopes. Explicitly declare epoch_tracker always.

- Unmask interface list IFNET_RLOCK_NOSLEEP(), interface address list
  IF_ADDR_RLOCK() and interface AF specific data IF_AFDATA_RLOCK() read
  locking macros to what they actually are - the net_epoch.
  Keeping them as is is very misleading. They all are named FOO_RLOCK(),
  while they no longer have lock semantics. Now they allow recursion and
  what's more important they now no longer guarantee protection against
  their companion WLOCK macros.
  Note: INP_HASH_RLOCK() has same problems, but not touched by this commit.

This is non functional mechanical change. The only functionally changed
functions are ni6_addrs() and ni6_store_addrs(), where we no longer enter
epoch recursively.

Discussed with:	jtl, gallatin
2019-01-09 01:11:19 +00:00
Mateusz Guzik
cc426dd319 Remove unused argument to priv_check_cred.
Patch mostly generated with cocinnelle:

@@
expression E1,E2;
@@

- priv_check_cred(E1,E2,0)
+ priv_check_cred(E1,E2)

Sponsored by:	The FreeBSD Foundation
2018-12-11 19:32:16 +00:00
Mark Johnston
9d2877fc3d Clamp the INPCB port hash tables to IPPORT_MAX + 1 chains.
Memory beyond that limit was previously unused, wasting roughly 1MB per
8GB of RAM.  Also retire INP_PCBLBGROUP_PORTHASH, which was identical to
INP_PCBPORTHASH.

Reviewed by:	glebius
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D17803
2018-12-05 17:06:00 +00:00
Mark Johnston
79db6fe7aa Plug some networking sysctl leaks.
Various network protocol sysctl handlers were not zero-filling their
output buffers and thus would export uninitialized stack memory to
userland.  Fix a number of such handlers.

Reported by:	Thomas Barabosch, Fraunhofer FKIE
Reviewed by:	tuexen
MFC after:	3 days
Security:	kernel memory disclosure
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D18301
2018-11-22 20:49:41 +00:00
Mark Johnston
d9ff5789be Remove redundant checks for a NULL lbgroup table.
No functional change intended.

MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17108
2018-11-01 15:52:49 +00:00
Mark Johnston
79ee680b65 Improve style in in_pcbinslbgrouphash() and related subroutines.
No functional change intended.

MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17107
2018-11-01 15:51:49 +00:00
Mark Johnston
54af3d0dac Fix synchronization of LB group access.
Lookups are protected by an epoch section, so the LB group linkage must
be a CK_LIST rather than a plain LIST.  Furthermore, we were not
deferring LB group frees, so in_pcbremlbgrouphash() could race with
readers and cause a use-after-free.

Reviewed by:	sbruno, Johannes Lundberg <johalun0@gmail.com>
Tested by:	gallatin
Approved by:	re (gjb)
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17031
2018-09-10 19:00:29 +00:00
Mark Johnston
a7026c7fd9 Use ratecheck(9) in in_pcbinslbgrouphash().
Reviewed by:	bz, Johannes Lundberg <johalun0@gmail.com>
Approved by:	re (kib)
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D17065
2018-09-07 21:11:41 +00:00
Mark Johnston
8be02ee4da Fix style bugs in in_pcblookup_lbgroup().
No functional change intended.

Reviewed by:	bz, Johannes Lundberg <johalun0@gmail.com>
Approved by:	re (rgrimes)
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17030
2018-09-05 15:04:11 +00:00
Mark Johnston
73ad0b6abf Use the correct malloc type in in_pcblbgroup_free().
Approved by:	re (kib)
Sponsored by:	The FreeBSD Foundation
2018-09-03 17:39:09 +00:00
Matt Macy
f9be038601 Fix in6_multi double free
This is actually several different bugs:
- The code is not designed to handle inpcb deletion after interface deletion
  - add reference for inpcb membership
- The multicast address has to be removed from interface lists when the refcount
  goes to zero OR when the interface goes away
  - decouple list disconnect from refcount (v6 only for now)
- ifmultiaddr can exist past being on interface lists
  - add flag for tracking whether or not it's enqueued
- deferring freeing moptions makes the incpb cleanup code simpler but opens the
  door wider still to races
  - call inp_gcmoptions synchronously after dropping the the inpcb lock

Fundamentally multicast needs a rewrite - but keep applying band-aids for now.

Tested by: kp
Reported by: novel, kp, lwhsu
2018-08-15 20:23:08 +00:00
Andrew Turner
5f901c92a8 Use the new VNET_DEFINE_STATIC macro when we are defining static VNET
variables.

Reviewed by:	bz
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D16147
2018-07-24 16:35:52 +00:00
Brooks Davis
3a20f06a1c Use uintptr_t alone when assigning to kvaddr_t variables.
Suggested by:	jhb
2018-07-10 13:03:06 +00:00
Brooks Davis
7524b4c14b Correct breakage on 32-bit platforms from r335979. 2018-07-06 10:03:33 +00:00
Brooks Davis
f38b68ae8a Make struct xinpcb and friends word-size independent.
Replace size_t members with ksize_t (uint64_t) and pointer members
(never used as pointers in userspace, but instead as unique
idenitifiers) with kvaddr_t (uint64_t). This makes the structs
identical between 32-bit and 64-bit ABIs.

On 64-bit bit systems, the ABI is maintained. On 32-bit systems,
this is an ABI breaking change. The ABI of most of these structs
was previously broken in r315662.  This also imposes a small API
change on userspace consumers who must handle kernel pointers
becoming virtual addresses.

PR:		228301 (exp-run by antoine)
Reviewed by:	jtl, kib, rwatson (various versions)
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D15386
2018-07-05 13:13:48 +00:00
Matt Macy
6573d7580b epoch(9): allow preemptible epochs to compose
- Add tracker argument to preemptible epochs
- Inline epoch read path in kernel and tied modules
- Change in_epoch to take an epoch as argument
- Simplify tfb_tcp_do_segment to not take a ti_locked argument,
  there's no longer any benefit to dropping the pcbinfo lock
  and trying to do so just adds an error prone branchfest to
  these functions
- Remove cases of same function recursion on the epoch as
  recursing is no longer free.
- Remove the the TAILQ_ENTRY and epoch_section from struct
  thread as the tracker field is now stack or heap allocated
  as appropriate.

Tested by: pho and Limelight Networks
Reviewed by: kbowling at llnw dot com
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D16066
2018-07-04 02:47:16 +00:00
Sean Bruno
45fc0718d8 Reap unused variable and assignment that had no effect. Noted by cross
compiling with gcc on mips.

Reviewed by:	mmacy
2018-06-24 21:36:37 +00:00
Matt Macy
3d348772e7 in_pcblookup_hash: validate inp before return
Post r335356 it is possible to have an inpcb on the hash lists that is
partially torn down. Validate before using. Also as a side effect of this
change the lock ordering issue between hash lock and inpcb no longer exists
allowing some simplification.

Reported by:	pho@
2018-06-21 18:40:15 +00:00
Matt Macy
feeef8509b Fix PCBGROUPS build post CK conversion of pcbinfo 2018-06-13 23:19:54 +00:00
Matt Macy
483305b99c Handle INP_FREED when looking up an inpcb
When hash table lookups are not serialized with in_pcbfree it will be
possible for callers to find an inpcb that has been marked free. We
need to check for this and return NULL.
2018-06-13 04:23:49 +00:00
Matt Macy
700e893c34 Defer inpcbport free in in_pcbremlists as well 2018-06-12 23:26:25 +00:00
Matt Macy
f09ee4fc01 Defer inpcbport free until after a grace period has elapsed
This is a dependency for inpcbinfo rlock conversion to epoch
2018-06-12 22:18:27 +00:00
Matt Macy
b872626dbe mechanical CK macro conversion of inpcbinfo lists
This is a dependency for converting the inpcbinfo hash and info rlocks
to epoch.
2018-06-12 22:18:20 +00:00
Matt Macy
addf2b2009 Defer inpcb deletion until after a grace period has elapsed
Deferring the actual free of the inpcb until after a grace
period has elapsed will allow us to convert the inpcbinfo
info and hash read locks to epoch.

Reviewed by: gallatin, jtl
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D15510
2018-06-12 22:18:15 +00:00
Sean Bruno
1a43cff92a Load balance sockets with new SO_REUSEPORT_LB option.
This patch adds a new socket option, SO_REUSEPORT_LB, which allow multiple
programs or threads to bind to the same port and incoming connections will be
load balanced using a hash function.

Most of the code was copied from a similar patch for DragonflyBSD.

However, in DragonflyBSD, load balancing is a global on/off setting and can not
be set per socket. This patch allows for simultaneous use of both the current
SO_REUSEPORT and the new SO_REUSEPORT_LB options on the same system.

Required changes to structures:
Globally change so_options from 16 to 32 bit value to allow for more options.
Add hashtable in pcbinfo to hold all SO_REUSEPORT_LB sockets.

Limitations:
As DragonflyBSD, a load balance group is limited to 256 pcbs (256 programs or
threads sharing the same socket).

This is a substantially different contribution as compared to its original
incarnation at svn r332894 and reverted at svn r332967.  Thanks to rwatson@
for the substantive feedback that is included in this commit.

Submitted by:	Johannes Lundberg <johalun0@gmail.com>
Obtained from:	DragonflyBSD
Relnotes:	Yes
Sponsored by:	Limelight Networks
Differential Revision:	https://reviews.freebsd.org/D11003
2018-06-06 15:45:57 +00:00
Matt Macy
62d733a11d in_pcbladdr: remove debug code that snuck in with ifa epoch conversion r334118 2018-05-27 06:47:09 +00:00
Matt Macy
4f6c66cc9c UDP: further performance improvements on tx
Cumulative throughput while running 64
  netperf -H $DUT -t UDP_STREAM -- -m 1
on a 2x8x2 SKL went from 1.1Mpps to 2.5Mpps

Single stream throughput increases from 910kpps to 1.18Mpps

Baseline:
https://people.freebsd.org/~mmacy/2018.05.11/udpsender2.svg

- Protect read access to global ifnet list with epoch
https://people.freebsd.org/~mmacy/2018.05.11/udpsender3.svg

- Protect short lived ifaddr references with epoch
https://people.freebsd.org/~mmacy/2018.05.11/udpsender4.svg

- Convert if_afdata read lock path to epoch
https://people.freebsd.org/~mmacy/2018.05.11/udpsender5.svg

A fix for the inpcbhash contention is pending sufficient time
on a canary at LLNW.

Reviewed by:	gallatin
Sponsored by:	Limelight Networks
Differential Revision:	https://reviews.freebsd.org/D15409
2018-05-23 21:02:14 +00:00
Matt Macy
f42a83f2a6 inpcb: revert deferred inpcb free pending further review 2018-05-21 16:13:43 +00:00
Matt Macy
1a3d880c26 in(s)_moptions: free before tearing down inpcb 2018-05-20 20:08:21 +00:00
Matt Macy
47d2a58560 inpcb: defer destruction of inpcb until after a grace period has elapsed
in_pcbfree will remove the incpb from the list and release the rtentry
while the vnet is set, but the actual destruction will be deferred
until any threads in a (not yet used) epoch section, no longer potentially
have references.
2018-05-20 04:38:04 +00:00