Kyle Evans [Wed, 20 Jan 2021 17:53:05 +0000 (11:53 -0600)]
504ebd612ec: kern: sonewconn: set so_options before pru_attach()
Protocol attachment has historically been able to observe and modify
so->so_options as needed, and it still can for newly created sockets. 779f106aa169 moved this to after pru_attach() when we re-acquire the
lock on the listening socket.
Restore the historical behavior so that pru_attach implementations can
consistently use it. Note that some pru_attach() do currently rely on
this, though that may change in the future. D28265 contains a change to
remove the use in TCP and IB/SDP bits, as resetting the requested linger
time on incoming connections seems questionable at best.
This does move the assignment out from under the head's listen lock, but
glebius notes that head won't be going away and applications cannot
assume any specific ordering with a race between a connection coming in
and the application changing socket options anyways.
TCP_LINGERTIME can be traced back to BSD 4.4 Lite and perhaps beyond, in
exactly the same form that it appears here modulo slightly different
context. It used to be the case that there was a single pr_usrreq
method with requests dispatched to it; these exact two lines appeared in
tcp_usrreq's PRU_ATTACH handling.
The only purpose of this that I can find is to cause surprising behavior
on accepted connections. Newly-created sockets will never hit these
paths as one cannot set SO_LINGER prior to socket(2). If SO_LINGER is
set on a listening socket and inherited, one would expect the timeout to
be inherited rather than changed arbitrarily like this -- noting that
SO_LINGER is nonsense on a listening socket beyond inheritance, since
they cannot be 'connected' by definition.
Neither Illumos nor Linux reset the timer like this based on testing and
inspection of Illumos, and testing of Linux.
Fix divide-by-zero panic when ASLR is enabled and superpages disabled
When locating the anonymous memory region for a vm_map with ASLR
enabled, we try to keep the slid base address aligned on a superpage
boundary to minimize pagetable fragmentation and maximize the potential
usage of superpage mappings. We can't (portably) do this if superpages
have been disabled by loader tunable and pagesizes[1] is 0, and it
would be less beneficial in that case anyway.
hkbd: Fix handling of keyboard ErrorRollOver reports
Ignore fantom keyboard state reports entirelly rather than ignore
RollOver states for each key separatelly. Latter results in spurious
release/push pairs of events on each fantom keyboard state report.
Reported by: Jan Martin Mikkelsen <janm_AT_transactionware_DOT_com>
Submitted by: Jan Martin Mikkelsen (initial version)
PR: 253249
MFC after: 1 week
ukbd: Fix handling of keyboard ErrorRollOver reports
Ignore fantom keyboard state reports entirelly rather than ignore
RollOver states for each key separatelly. Latter results in spurious
release/push pairs of events on each fantom keyboard state report.
Reported by: Jan Martin Mikkelsen <janm_AT_transactionware_DOT_com>
Submitted by: Jan Martin Mikkelsen (initial version)
PR: 253249
MFC after: 1 week
hidraw: Make HIDIOCGRDESCSIZE ioctl return report descriptor size
defined by hardware rather than cached one to match HIDIOCGRDESC ioctl.
This fixes errors reported by hid-tools being run against /dev/hidraw#
device node belonging to driver which overloads report descriptor.
ofwfb: fix incorrect colors on powerpc* and add new tunable parameters
- Implements little-endian support (powerpc64le)
- Adds 'hw.ofwfb.physaddr' kernel parameter so user can manually
provide correct address if it's not detected correctly
- Adds 'hw.ofwfb.argb32_pixel' so user can set it manually if
colors are inverted due to incorrect pixel format (default = 1)
- Automatically selects RGBA32 pixel format if NVidia graphic adapter
is detected (sets hw.ofwfb.argb32_pixel=0)
Machines equipped with NVidia graphic adapters tend to use RGBA32
pixel format. By default ARGB32 pixel format is used, proved to work
on machines equipped with ATI graphic adapter and the onboard adapter
used on Talos II and Blackbird machines from Raptor Computing Systems.
Mitchell Horne [Wed, 20 Jan 2021 15:07:53 +0000 (11:07 -0400)]
cgem: improve usage of busdma(9) KPI
BUS_DMA_NOCACHE should only be used when one needs to guarantee the
created mapping has uncached memory attributes, usually as a result
of buggy hardware. Normal use cases should pass BUS_DMA_COHERENT, to
create an appropriate mapping based on the flags passed to
bus_dma_tag_create().
This should have no functional change, since the DMA tags in this driver
are created without the BUS_DMA_COHERENT flag.
Reported by: mmel
Reviewed by: mmel, Thomas Skibo <thomas-bsd@skibo.net>
Thomas Skibo [Mon, 11 Jan 2021 20:58:12 +0000 (16:58 -0400)]
ddb: fix show devmap output on 32-bit arm
The output has been broken since 1b6dd6d772ca. Casting to uintmax_t
before the call to printf is necessary to ensure that 32-bit addresses
are interpreted correctly.
Yannis Planus [Thu, 28 Jan 2021 13:59:07 +0000 (14:59 +0100)]
pf: duplicate frames only once when using dup-to pf rule
When using DUP-TO rule, frames are duplicated 3 times on both output
interfaces and duplication interface. Add a flag to not duplicate a
duplicated frame.
Inspired by a patch from MiĆosz Kaniewski milosz.kaniewski at gmail.com
https://lists.freebsd.org/pipermail/freebsd-pf/2015-November/007886.html
Toomas Soome [Thu, 28 Jan 2021 07:45:47 +0000 (09:45 +0200)]
loader: unload command should reset tg_kernel_supported in gfx_state
While loading kernel, we check if vt/vbe backend support is included in
kernel and set the tg_kernel_supported flag in gfx_state. unload
command needs to reset this flag to allow next load to perform
this check with new kernel.
Dimitry Andric [Wed, 27 Jan 2021 21:28:43 +0000 (22:28 +0100)]
Fix loader detection of vbefb support on !amd64
On i386, after 6c7a932d0b8baaaee16eca0ba061bfa6e0e57bfd, the vbefb vt
driver was no longer detected by the loader, if any kernel module was
loaded after the kernel itself.
This was caused by the parse_vt_drv_set() function being called multiple
times, resetting the detection flag. (It was called multiple times,
becuase i386 .ko files are shared objects like the kernel proper, while
this is not the case on amd64.)
Fix this by skipping the set_vt_drv_set lookup if vbefb was already
detected.
Mark Johnston [Tue, 16 Feb 2021 14:30:21 +0000 (09:30 -0500)]
linux: Unmap the VDSO page when unloading
linux_shared_page_init() creates an object and grabs and maps a single
page to back the VDSO. When destroying the VDSO object, we failed to
destroy the mapping and free KVA. Fix this.
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D28696
xen-blkback: fix leak of grant maps on ring setup failure
Multi page rings are mapped using a single hypercall that gets passed
an array of grants to map. One of the grants in the array failing to
map would lead to the failure of the whole ring setup operation, but
there was no cleanup of the rest of the grant maps in the array that
could have likely been created as a result of the hypercall.
Add proper cleanup on the failure path during ring setup to unmap any
grants that could have been created.
Alexander Motin [Sun, 24 Jan 2021 19:23:04 +0000 (14:23 -0500)]
Exclude reserved iSCSI Initiator Task Tag.
RFC 7143 (11.2.1.8):
An ITT value of 0xffffffff is reserved and MUST NOT be assigned for a
task by the initiator. The only instance in which it may be seen on
the wire is in a target-initiated NOP-In PDU (Section 11.19) and in
the initiator response to that PDU, if necessary.
Alexander Motin [Sun, 24 Jan 2021 18:58:29 +0000 (13:58 -0500)]
Exclude reserved iSCSI Target Transfer Tag.
RFC 7143 (11.7.4):
The Target Transfer Tag values are not specified by this protocol,
except that the value 0xffffffff is reserved and means that the
Target Transfer Tag is not supplied.
Alexander Motin [Wed, 17 Feb 2021 02:15:28 +0000 (21:15 -0500)]
cxgbe(4): Save proper zone index on low memory in refill_fl().
When refill_fl() fails to allocate large (9/16KB) mbuf cluster, it
falls back to safe (4KB) ones. But it still saved into sd->zidx
the original fl->zidx instead of fl->safe_zidx. It caused problems
with the later use of that cluster, including memory and/or data
corruption.
While there, make refill_fl() to use the safe zone for all following
clusters for the call, since it is unlikely that large succeed.
MFC after: 3 days
Sponsored by: iXsystems, Inc.
Reviewed by: np, jhb
Differential Revision: https://reviews.freebsd.org/D28716
Jung-uk Kim [Wed, 17 Feb 2021 07:22:47 +0000 (02:22 -0500)]
lex: Do not let input() return 0 when end-of-file is reached
Importing flex 2.6.4 has introduced a regression: input() now returns 0
instead of EOF to indicate that the end of input was reached, just like
traditional AT&T and POSIX lex. Note the behavior contradicts flex(1).
See "INCOMPATIBILITIES WITH LEX AND POSIX" section for information.
This incompatibility traces back to the original version and documented
in its manual page by the Vern Paxson.
Apparently, it has been reported in a few places, e.g.,
Unfortunately, this also breaks the scanner used by libdtrace and
dtrace is unable to resolve some probe argument types as a result. See
PR253440 for more information.
Note the regression was introduced by the following upstream commit
without any explanation or documentation change:
Now we restore the traditional flex behavior unless lex-compatibility
mode is set with "-l" option because I believe the author originally
wanted to make it more lex and POSIX compatible.
Martin Matuska [Mon, 22 Feb 2021 17:37:47 +0000 (18:37 +0100)]
zfs: disable use of hardware crypto offload drivers
From openzfs-master e7adccf7f commit message:
First, the crypto request completion handler contains a bug in that it
fails to reset fs_done correctly after the request is completed. This
is only a problem for asynchronous drivers. Second, some hardware
drivers have input constraints which ZFS does not satisfy. For
instance, ccp(4) apparently requires the AAD length for AES-GCM to be a
multiple of the cipher block size, and with qat(4) the AES-GCM AAD
length may not be longer than 240 bytes. FreeBSD's generic crypto
framework doesn't have a mechanism to automatically fall back to a
software implementation if a hardware driver cannot process a request,
and ZFS does not tolerate such errors.
Martin Matuska [Mon, 22 Feb 2021 17:05:07 +0000 (18:05 +0100)]
zfs: fix panic if scrubbing after removing a slog device
From openzfs-master 11f2e9a4 commit message:
vdev_ops: don't try to call vdev_op_hold or vdev_op_rele when NULL
This prevents a panic after a SLOG add/removal on the root pool followed
by a zpool scrub.
When a SLOG is removed, a hole takes its place - the vdev_ops for a hole
is vdev_hole_ops, which defines the handler functions of vdev_op_hold
and vdev_op_rele as NULL.
Patch Author: Patrick Mooney <pmooney@pfmooney.com>
Michal Krawczyk [Thu, 18 Feb 2021 09:00:58 +0000 (10:00 +0100)]
MFC 1c808fcd859f: Allocate BAR for ENA MSIx vector table
In the new ENA-based instances like c6gn, the vector table moved to a
new PCIe bar - BAR1. Previously it was always located on the BAR0, so
the resources were already allocated together with the registers.
As the FreeBSD isn't doing any resource allocation behind the scenes,
the driver is responsible to allocate them explicitly, before other
parts of the OS (like the PCI code allocating MSIx) will be able to
access them.
To determine dynamically BAR on which the MSIx vector table is present
the pci_msix_table_bar() is being used and the new BAR is allocated if
needed.
Stefan EĂer [Wed, 17 Feb 2021 21:56:16 +0000 (22:56 +0100)]
bc: Upgrade to version 3.3.0
This update changes the behavior of "-e" or "-f" in BC_ENV_ARGS:
Use of these options on the command line makes bc exit after executing
the given commands. These options will not cause bc to exit when
passed via the environment (but EOF in STDIN or -e or -f on the
command line will make bc exit as before).
The same applies to DC_ENV_ARGS with regard to the dc program.
Lutz Donnerhacke [Wed, 10 Feb 2021 10:47:38 +0000 (11:47 +0100)]
netgraph/ng_bridge: Add counters for the first link, too
For broadcast, multicast and unknown unicast, the replication loop
sends a copy of the packet to each link, beside the first one. This
special path is handled later, but the counters are not updated.
Factor out the common send and count actions as a function.
netgraph/ng_bridge: Document staleness in multithreaded operation
In the data path of ng_bridge(4), the only value of the host struct,
which needs to be modified, is the staleness, which is reset every
time a frame is received. It's save to leave the code as it is.
This patch is part of a series to make ng_bridge(4) multithreaded.
In a earlier version of ng_bridge(4) the exernal visible host entry
structure was a strict subset of the internal one. So internal view
was a direct annotation of the external structure. This strict
inheritance was lost many versions ago. There is no need to
encapsulate a part of the internal represntation as a separate
structure.
This patch is a preparation to make the internal structure read only
in the data path in order to make ng_bridge(4) multithreaded.
Lutz Donnerhacke [Wed, 13 Jan 2021 22:18:55 +0000 (23:18 +0100)]
netgraph/ng_bridge: Make simple internal functions read-only
The data path in netgraph is designed to work on an read only state of
the whole netgraph network. Currently this is achived by convention,
there is no technical enforcment. In the case of NETGRAPH_DEBUG all
nodes can be annotated for debugging purposes, so the strict
enforcment needs to be lifted for this purpose.
This patch is part of a series to make ng_bridge multithreaded, which
is done by rewrite the data path to operate on const.
netgraph/ng_bridge: Derive forwarding mode from first attached hook
Handling of unknown MACs on an bridge with incomplete learning
capabilites (aka uplink ports) can be defined in different ways.
The classical approach is to broadcast unicast frames send to an
unknown MAC, because the unknown devices can be everywhere. This mode
is default for ng_bridge(4).
In the case of dedicated uplink ports, which prohibit learning of MAC
addresses in order to save memory and CPU cycles, the broadcast
approach is dangerous. All traffic to the uplink port is broadcasted
to every downlink port, too. In this case, it's better to restrict the
distribution of frames to unknown MAC to the uplink ports only.
In order to keep the chance small and the handling as natural as
possible, the first attached link is used to determine the behaviour
of the bridge: If it is an "uplink" port, then the bridge switch from
classical mode to restricted mode.
netgraph/ng_bridge: Introduce "uplink" ports without MAC learning
The ng_bridge(4) node is designed to work in moderately small
environments. Connecting such a node to a larger network rapidly fills
the MAC table for no reason. It even become complicated to obtain data
from the gettable message, because the result is too large to
transmit.
This patch introduces, two new functionality bits on the hooks:
- Allow or disallow MAC address learning for incoming patckets.
- Allow or disallow sending unknown MACs through this hook.
Uplinks are characterized by denied learing while sending out
unknowns. Normal links are charaterized by allowed learning and
sending out unknowns.
Jamie Gritton [Fri, 19 Feb 2021 22:13:35 +0000 (14:13 -0800)]
MFC jail: Change both root and working directories in jail_attach(2)
jail_attach(2) performs an internal chroot operation, leaving it up to
the calling process to assure the working directory is inside the jail.
Add a matching internal chdir operation to the jail's root. Also
ignore kern.chroot_allow_open_directories, and always disallow the
operation if there are any directory descriptors open.
Guangyuan Yang [Mon, 15 Feb 2021 22:03:37 +0000 (22:03 +0000)]
pxeboot(8): remove antiquated information
While I was there:
- Fix some typos
- Fix an excessive argument "indent" reported by mandoc -Tlint
- Replace a dead link with the one suggested by
https://www.uefi.org/uefi
Revert 3c4fd2463bb2 since upstream libcxxrt fixed it in another way
In 0ee0dbfb0d26cf4bc37f24f12e76c7f532b0f368 I imported a more recent
libcxxrt snapshot, which includes an upstream fix for the padding of
struct _Unwind_Exception:
Since having both fixes makes the struct too large again, it leads to
SIGBUSes when throwing exceptions on amd64 (or other LP64 arches). This
is most easily tested by running kyua without any arguments.
It looks like our fix is no longer needed now, so revert it to reduce
diffs against upstream.
Ravi Pokala [Tue, 16 Feb 2021 08:03:32 +0000 (00:03 -0800)]
nvdimm(4): Export NVDIMM health flags via sysctl
The ACPI NFIT specification defines a set of "NVDIMM State Flags". These
flags are already reported by `acpidump -t', but this change makes them
available on a per-device basis, in a format that is more easily parsed.
To simplify this, introduce acpi_nfit_get_memory_maps_by_dimm(), which
locates the (ACPI_NFIT_MEMORY_MAP)s associated with a given
(nfit_handle_t).
Reviewed by: mav, cem
Tested by: mav, rpokala (version for stable/12)
MFC after: 3 days
Sponsored by: Panasas
Differential Revision: https://reviews.freebsd.org/D28700
Dimitry Andric [Fri, 19 Feb 2021 18:18:22 +0000 (19:18 +0100)]
Revert 3c4fd2463bb2 since upstream libcxxrt fixed it in another way
In 0ee0dbfb0d26cf4bc37f24f12e76c7f532b0f368 I imported a more recent
libcxxrt snapshot, which includes an upstream fix for the padding of
struct _Unwind_Exception:
Since having both fixes makes the struct too large again, it leads to
SIGBUSes when throwing exceptions on amd64 (or other LP64 arches). This
is most easily tested by running kyua without any arguments.
It looks like our fix is no longer needed now, so revert it to reduce
diffs against upstream.
Kyle Evans [Fri, 12 Feb 2021 00:58:27 +0000 (18:58 -0600)]
pkg(7): address minor nits (mostly clang-analyze complaints)
- One (1) spurious whitespace.
- One (1) occurrence of "random(3) bad, arc4random(3)" good.
- Three (3) writes that will never be seen.
The latter two points are complaints from clang-analyze. Switching to
arc4random(3) is decidedly a good idea because we weren't doing any kind
of PRNG seeding anyways. The discarded assignments are arguably good
for future-proofing, but it's better to improve the S/N ratio from
clang-analyze.
Kyle Evans [Fri, 12 Feb 2021 00:58:26 +0000 (18:58 -0600)]
pkg(7): add an -r reponame option for bootstrap and add
This is limited to bootstrap/add because some real pkg(8) commands
have -r flags with an incompatible meaning/usage, e.g., pkg-audit.
pkg(7) will still commence the search as it has, but it will ignore any
repo objects without the given name so that overrides and whatnot still
work as expected.
The use of it for add is noted in the manpage; notably, that the
signature config for that repository will be used over global config if
it's specified. i.e., pkg(7) should assume that the given pkg did come
from that repository and treat it appropriately.
Mark Johnston [Sat, 20 Feb 2021 02:44:20 +0000 (21:44 -0500)]
libdtrace: Trivial style fixes to force dt_lex.c to be regenerated
After commit 8ba333e02e ("libdtrace: Stop relying on lex
compatibility"), there have been several reports of incremental
buildworlds failing since make does not know that dt_lex.c needs to be
regenerated, and I want to avoid this when merging to stable/13.
Mark Johnston [Wed, 17 Feb 2021 15:49:38 +0000 (10:49 -0500)]
libdtrace: Stop relying on lex compatibility
It does not appear to be required, and as of commit 6b7e592c215f
("lex: Do not let input() return 0 when end-of-file is reached") it
causes input to return 0 instead of EOF when end-of-input is reached.
Alan Somers [Mon, 15 Feb 2021 22:51:31 +0000 (15:51 -0700)]
libpmc: fix linking with C programs
Revision r334749 Added some C++ code to libpmc. It didn't change the ABI,
but it did introduce a dependency on libc++. Nobody noticed because every
program that in the base system that uses libpmc is also C++.
Reported-by: Dom Dwyer <dom@itsallbroken.com>
Reviewed By: vangyzen
Differential Revision: https://reviews.freebsd.org/D28550
Allan Jude [Sun, 14 Feb 2021 18:39:09 +0000 (18:39 +0000)]
Use iflib_if_init_locked() during media change instead of iflib_init_locked().
iflib_init_locked() assumes that iflib_stop() has been called, however,
it is not called for media changes.
iflib_if_init_locked() calls stop then init, so fixes the problem.
PR: 253473
Sponsored by: Juniper Networks, Inc., Klara, Inc.
Jamie Gritton [Tue, 16 Feb 2021 19:19:13 +0000 (11:19 -0800)]
MFC jail: Handle a possible race between jail_remove(2) and fork(2)
jail_remove(2) includes a loop that sends SIGKILL to all processes
in a jail, but skips processes in PRS_NEW state. Thus it is possible
the a process in mid-fork(2) during jail removal can survive the jail
being removed.
Add a prison flag PR_REMOVE, which is checked before the new process
returns. If the jail is being removed, the process will then exit.
Also check this flag in jail_attach(2) which has a similar issue.
NOTE 1: There is no need to dump and reload repositories, and the
working copy format is still the same as Subversion 1.8 through 1.13.
NOTE 2: The upstream release also contains a fix for a security issue in
mod_dav_svn (CVE-2020-17525), but since we do not build or use any
Apache modules, it is not an issue for the FreeBSD base system.
Dimitry Andric [Wed, 10 Feb 2021 22:28:43 +0000 (23:28 +0100)]
Fix incorrect hypotl(3) result with subnormal numbers
This adjusts the factor used to scale the subnormal numbers, so it
becomes the right value after adjusting its exponent. Thanks to Steve
Kargl for finding the most elegant fix.
Also enable the hypot tests, and add a test case for this bug.
Fix lib/msun/test builds on platforms without 80-bit long doubles
After d3338f3355a612cf385632291f46c5777bba8d18, the lib/msun test case
'hypotl_near_underflow' would fail to compile on platforms where long
doubles weren't 80 bit, like on x86. Disable this particular test on
such platforms for now.
MFC 12148d4300db:
Fix for locking order reversal in USB audio driver, when using mmap().
Locking the second lock which causes the LOR, can be skipped because
the code updating the shared variables is always executing from the
same USB thread.
lock order reversal:
1st 0xfffff80005cc3840 pcm7:play:dsp7.p0 (pcm play channel, sleep mutex)
@ usb_transfer.c:2342
2nd 0xfffff80005cc3860 pcm7:record:dsp7.r0 (pcm record channel, sleep mutex)
@ uaudio.c:2317
lock order pcm record channel -> pcm play channel established at:
witness_checkorder+0x461
__mtx_lock_flags+0x98
dsp_mmap_single+0x151
vm_mmap_cdev+0x65
devfs_mmap_f+0x143
kern_mmap_req+0x594
sys_mmap+0x46
amd64_syscall+0x12e
fast_syscall_common+0xf8
lock order pcm play channel -> pcm record channel attempted at:
witness_checkorder+0xd82
__mtx_lock_flags+0x98
uaudio_chan_play_callback+0xeb
usbd_callback_wrapper+0x7ec
usb_command_wrapper+0x7e
usb_callback_proc+0x8e
usb_process+0xf3
fork_exit+0x80
fork_trampoline+0xe
Found by: Stefan Ehmann <shoesoft@gmx.net>
Sponsored by: Mellanox Technologies // NVIDIA Networking
Martin Matuska [Mon, 15 Feb 2021 08:10:01 +0000 (09:10 +0100)]
zfs: Avoid updating the L2ARC device header unnecessarily
From openzfs-master 0ae184a6b commit message:
If we do not write any buffers to the cache device and the evict hand
has not advanced do not update the cache device header.
Martin Matuska [Mon, 15 Feb 2021 07:40:27 +0000 (08:40 +0100)]
zfs: fix RAIDZ2/3 not healing parity with 2+ bad disks
From openzfs-master 62d4287f2 commit message:
When scrubbing, (non-sequential) resilvering, or correcting a checksum
error using RAIDZ parity, ZFS should heal any incorrect RAIDZ parity by
overwriting it. For example, if P disks are silently corrupted (P being
the number of failures tolerated; e.g. RAIDZ2 has P=2), `zpool scrub`
should detect and heal all the bad state on these disks, including
parity. This way if there is a subsequent failure we are fully
protected.
With RAIDZ2 or RAIDZ3, a block can have silent damage to a parity
sector, and also damage (silent or known) to a data sector. In this
case the parity should be healed but it is not.
Neel Chauhan [Tue, 2 Feb 2021 21:24:17 +0000 (13:24 -0800)]
Allow setting alias port ranges in libalias and ipfw.
This will allow a system to be a true RFC 6598 NAT444 setup, where each
network segment (e.g. user, subnet) can have their own dedicated port
aliasing ranges.
Kristof Provost [Mon, 8 Feb 2021 09:04:27 +0000 (10:04 +0100)]
Widen ifnet_detach_sxlock coverage
Widen the ifnet_detach_sxlock to cover the entire vnet sysuninit code.
This ensures that we can't end up having the vnet_sysuninit free the UDP
pcb while the detach code is running and trying to purge the UDP pcb.