Due to a weakness in the TLS 1.0 protocol, OpenSSL will periodically
send empty TLS records ("empty fragments"). These TLS records have no
payload (and thus a page count of zero). m_uiotombuf_nomap() was
returning NULL instead of an empty mbuf, and a few places needed to be
updated to treat an empty TLS record as having a page count of "1" as
0 means "no work to do" (e.g. nothing to encrypt, or nothing to mark
ready via sbready()).
Reviewed by: gallatin
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D26729
Allow TLS records to be decrypted in the kernel after being received
by a NIC. At a high level this is somewhat similar to software KTLS
for the transmit path except in reverse. Protocols enqueue mbufs
containing encrypted TLS records (or portions of records) into the
tail of a socket buffer and the KTLS layer decrypts those records
before returning them to userland applications. However, there is an
important difference:
- In the transmit case, the socket buffer is always a single "record"
holding a chain of mbufs. Not-yet-encrypted mbufs are marked not
ready (M_NOTREADY) and released to protocols for transmit by marking
mbufs ready once their data is encrypted.
- In the receive case, incoming (encrypted) data appended to the
socket buffer is still a single stream of data from the protocol,
but decrypted TLS records are stored as separate records in the
socket buffer and read individually via recvmsg().
Initially I tried to make this work by marking incoming mbufs as
M_NOTREADY, but there didn't seemed to be a non-gross way to deal with
picking a portion of the mbuf chain and turning it into a new record
in the socket buffer after decrypting the TLS record it contained
(along with prepending a control message). Also, such mbufs would
also need to be "pinned" in some way while they are being decrypted
such that a concurrent sbcut() wouldn't free them out from under the
thread performing decryption.
As such, I settled on the following solution:
- Socket buffers now contain an additional chain of mbufs (sb_mtls,
sb_mtlstail, and sb_tlscc) containing encrypted mbufs appended by
the protocol layer. These mbufs are still marked M_NOTREADY, but
soreceive*() generally don't know about them (except that they will
block waiting for data to be decrypted for a blocking read).
- Each time a new mbuf is appended to this TLS mbuf chain, the socket
buffer peeks at the TLS record header at the head of the chain to
determine the encrypted record's length. If enough data is queued
for the TLS record, the socket is placed on a per-CPU TLS workqueue
(reusing the existing KTLS workqueues and worker threads).
- The worker thread loops over the TLS mbuf chain decrypting records
until it runs out of data. Each record is detached from the TLS
mbuf chain while it is being decrypted to keep the mbufs "pinned".
However, a new sb_dtlscc field tracks the character count of the
detached record and sbcut()/sbdrop() is updated to account for the
detached record. After the record is decrypted, the worker thread
first checks to see if sbcut() dropped the record. If so, it is
freed (can happen when a socket is closed with pending data).
Otherwise, the header and trailer are stripped from the original
mbufs, a control message is created holding the decrypted TLS
header, and the decrypted TLS record is appended to the "normal"
socket buffer chain.
(Side note: the SBCHECK() infrastucture was very useful as I was
able to add assertions there about the TLS chain that caught several
bugs during development.)
Tested by: rmacklem (various versions)
Relnotes: yes
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D24628
They have more differencies than similarities. For now there is lots
of code that would check for M_EXT only and work correctly on M_EXTPG
buffers, so still carry M_EXT bit together with M_EXTPG. However,
prepare some code for explicit check for M_EXTPG.
Reviewed by: gallatin
Differential Revision: https://reviews.freebsd.org/D24598
While the original implementation of unmapped mbufs was a large
step forward in terms of reducing cache misses by enabling mbufs
to carry more than a single page for sendfile, they are rather
cache unfriendly when accessing the ext_pgs metadata and
data. This is because the ext_pgs part of the mbuf is allocated
separately, and almost guaranteed to be cold in cache.
This change takes advantage of the fact that unmapped mbufs
are never used at the same time as pkthdr mbufs. Given this
fact, we can overlap the ext_pgs metadata with the mbuf
pkthdr, and carry the ext_pgs meta directly in the mbuf itself.
Similarly, we can carry the ext_pgs data (TLS hdr/trailer/array
of pages) directly after the existing m_ext.
In order to be able to carry 5 pages (which is the minimum
required for a 16K TLS record which is not perfectly aligned) on
LP64, I've had to steal ext_arg2. The only user of this in the
xmit path is sendfile, and I've adjusted it to use arg1 when
using unmapped mbufs.
This change is almost entirely mechanical, except that we
change mb_alloc_ext_pgs() to no longer allow allocating
pkthdrs, the change to avoid ext_arg2 as mentioned above,
and the removal of the ext_pgs zone,
This change saves roughly 2% "raw" CPU (~59% -> 57%), or over
3% "scaled" CPU on a Netflix 100% software kTLS workload at
90+ Gb/s on Broadwell Xeons.
In a follow-on commit, I plan to remove some hacks to avoid
access ext_pgs fields of mbufs, since they will now be in
cache.
Many thanks to glebius for helping to make this better in
the Netflix tree.
Reviewed by: hselasky, jhb, rrs, glebius (early version)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D24213
If LOCAL_CREDS is set on a unix socket and sendfile() is called,
sendfile will call uipc_send(PRUS_NOTREADY), prepending a control
message to the M_NOTREADY mbufs. uipc_send() then calls
sbappendcontrol() instead of sbappend(), and sbappendcontrol() would
erroneously clear M_NOTREADY.
Pass send flags to sbappendcontrol(), like we do for sbappend(), to
preserve M_READY when necessary.
Reported by: syzkaller
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D24333
KTLS uses the embedded header and trailer fields of unmapped
mbufs. This can lead to "silly" buffer lengths, where we have an
mbuf chain that will create a scatter/gather lists with a
regular pattern of 13 bytes followed by 16 bytes between each
adjacent TLS record.
For software ktls we typically wind up with a pattern where we
have several TLS records encrypted, and made ready at once. When
these records are made ready, we can coalesce these silly buffers
in sbready_compress by copying 13b TLS header of the next record
into the 16b TLS trailer of the current record. After doing so,
we now have a small 29 byte chunk between each TLS record.
This marginally increases PCIe bus efficiency. We've seen an
almost 1Gb/s increase in peak throughput on Broadwell based Xeons
running a 100% software TLS workload with Mellanox ConnectX-4
NICs.
Note that this change is ifdef'ed for KTLS, as KTLS is currently
the only user of the hdr/trailer feature of unmapped mbufs, and
peeking into them is expensive, since the ext_pgs struct lives in
separately allocated memory, and may be cold in cache.
This optimization is not applicable to HW ("NIC") TLS, as that
depends on having the entire TLS record described by a single
unmapped mbuf, so we cannot shift parts of the record between
mbufs for HW TLS.
Reviewed by: jhb, hselasky, scottl
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D24204
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
r23081 introduced kern.dummy oid as a semi ABI compat for kern.maxsockbuf
that was moved to a new namespace. It never functioned as an alias of any
kind and was just returning 0 unconditionally, hence it was probably
provided to keep some 3rd party programmes happy about sysctl(3) not
reporting an error because of non-existing oid.
After nearly 23 years it seems reasonable to just hide it from sysctl(8)
list not to cause unnecessary confusion as for its purpose.
Reported by: Antranig Vartanian <antranigv@freebsd.am>
Reviewed by: kib (mentor)
Approved by: kib (mentor)
Differential Revision: https://reviews.freebsd.org/D22982
KTLS adds support for in-kernel framing and encryption of Transport
Layer Security (1.0-1.2) data on TCP sockets. KTLS only supports
offload of TLS for transmitted data. Key negotation must still be
performed in userland. Once completed, transmit session keys for a
connection are provided to the kernel via a new TCP_TXTLS_ENABLE
socket option. All subsequent data transmitted on the socket is
placed into TLS frames and encrypted using the supplied keys.
Any data written to a KTLS-enabled socket via write(2), aio_write(2),
or sendfile(2) is assumed to be application data and is encoded in TLS
frames with an application data type. Individual records can be sent
with a custom type (e.g. handshake messages) via sendmsg(2) with a new
control message (TLS_SET_RECORD_TYPE) specifying the record type.
At present, rekeying is not supported though the in-kernel framework
should support rekeying.
KTLS makes use of the recently added unmapped mbufs to store TLS
frames in the socket buffer. Each TLS frame is described by a single
ext_pgs mbuf. The ext_pgs structure contains the header of the TLS
record (and trailer for encrypted records) as well as references to
the associated TLS session.
KTLS supports two primary methods of encrypting TLS frames: software
TLS and ifnet TLS.
Software TLS marks mbufs holding socket data as not ready via
M_NOTREADY similar to sendfile(2) when TLS framing information is
added to an unmapped mbuf in ktls_frame(). ktls_enqueue() is then
called to schedule TLS frames for encryption. In the case of
sendfile_iodone() calls ktls_enqueue() instead of pru_ready() leaving
the mbufs marked M_NOTREADY until encryption is completed. For other
writes (vn_sendfile when pages are available, write(2), etc.), the
PRUS_NOTREADY is set when invoking pru_send() along with invoking
ktls_enqueue().
A pool of worker threads (the "KTLS" kernel process) encrypts TLS
frames queued via ktls_enqueue(). Each TLS frame is temporarily
mapped using the direct map and passed to a software encryption
backend to perform the actual encryption.
(Note: The use of PHYS_TO_DMAP could be replaced with sf_bufs if
someone wished to make this work on architectures without a direct
map.)
KTLS supports pluggable software encryption backends. Internally,
Netflix uses proprietary pure-software backends. This commit includes
a simple backend in a new ktls_ocf.ko module that uses the kernel's
OpenCrypto framework to provide AES-GCM encryption of TLS frames. As
a result, software TLS is now a bit of a misnomer as it can make use
of hardware crypto accelerators.
Once software encryption has finished, the TLS frame mbufs are marked
ready via pru_ready(). At this point, the encrypted data appears as
regular payload to the TCP stack stored in unmapped mbufs.
ifnet TLS permits a NIC to offload the TLS encryption and TCP
segmentation. In this mode, a new send tag type (IF_SND_TAG_TYPE_TLS)
is allocated on the interface a socket is routed over and associated
with a TLS session. TLS records for a TLS session using ifnet TLS are
not marked M_NOTREADY but are passed down the stack unencrypted. The
ip_output_send() and ip6_output_send() helper functions that apply
send tags to outbound IP packets verify that the send tag of the TLS
record matches the outbound interface. If so, the packet is tagged
with the TLS send tag and sent to the interface. The NIC device
driver must recognize packets with the TLS send tag and schedule them
for TLS encryption and TCP segmentation. If the the outbound
interface does not match the interface in the TLS send tag, the packet
is dropped. In addition, a task is scheduled to refresh the TLS send
tag for the TLS session. If a new TLS send tag cannot be allocated,
the connection is dropped. If a new TLS send tag is allocated,
however, subsequent packets will be tagged with the correct TLS send
tag. (This latter case has been tested by configuring both ports of a
Chelsio T6 in a lagg and failing over from one port to another. As
the connections migrated to the new port, new TLS send tags were
allocated for the new port and connections resumed without being
dropped.)
ifnet TLS can be enabled and disabled on supported network interfaces
via new '[-]txtls[46]' options to ifconfig(8). ifnet TLS is supported
across both vlan devices and lagg interfaces using failover, lacp with
flowid enabled, or lacp with flowid enabled.
Applications may request the current KTLS mode of a connection via a
new TCP_TXTLS_MODE socket option. They can also use this socket
option to toggle between software and ifnet TLS modes.
In addition, a testing tool is available in tools/tools/switch_tls.
This is modeled on tcpdrop and uses similar syntax. However, instead
of dropping connections, -s is used to force KTLS connections to
switch to software TLS and -i is used to switch to ifnet TLS.
Various sysctls and counters are available under the kern.ipc.tls
sysctl node. The kern.ipc.tls.enable node must be set to true to
enable KTLS (it is off by default). The use of unmapped mbufs must
also be enabled via kern.ipc.mb_use_ext_pgs to enable KTLS.
KTLS is enabled via the KERN_TLS kernel option.
This patch is the culmination of years of work by several folks
including Scott Long and Randall Stewart for the original design and
implementation; Drew Gallatin for several optimizations including the
use of ext_pgs mbufs, the M_NOTREADY mechanism for TLS records
awaiting software encryption, and pluggable software crypto backends;
and John Baldwin for modifications to support hardware TLS offload.
Reviewed by: gallatin, hselasky, rrs
Obtained from: Netflix
Sponsored by: Netflix, Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D21277
Apply similar logic from sbcompress to pending data in the socket
buffer once it is marked ready via sbready. Normally sbcompress
merges small mbufs to reduce the length of mbuf chains in the socket
buffer. However, sbcompress cannot do this for mbufs marked
M_NOTREADY. sbcompress_ready is now called from sbready when mbufs
are marked ready to merge small mbuf chains once the data is available
to copy.
Submitted by: gallatin (earlier version)
Reviewed by: gallatin, hselasky, rrs
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20616
Unmapped mbufs allow sendfile to carry multiple pages of data in a
single mbuf, without mapping those pages. It is a requirement for
Netflix's in-kernel TLS, and provides a 5-10% CPU savings on heavy web
serving workloads when used by sendfile, due to effectively
compressing socket buffers by an order of magnitude, and hence
reducing cache misses.
For this new external mbuf buffer type (EXT_PGS), the ext_buf pointer
now points to a struct mbuf_ext_pgs structure instead of a data
buffer. This structure contains an array of physical addresses (this
reduces cache misses compared to an earlier version that stored an
array of vm_page_t pointers). It also stores additional fields needed
for in-kernel TLS such as the TLS header and trailer data that are
currently unused. To more easily detect these mbufs, the M_NOMAP flag
is set in m_flags in addition to M_EXT.
Various functions like m_copydata() have been updated to safely access
packet contents (using uiomove_fromphys()), to make things like BPF
safe.
NIC drivers advertise support for unmapped mbufs on transmit via a new
IFCAP_NOMAP capability. This capability can be toggled via the new
'nomap' and '-nomap' ifconfig(8) commands. For NIC drivers that only
transmit packet contents via DMA and use bus_dma, adding the
capability to if_capabilities and if_capenable should be all that is
required.
If a NIC does not support unmapped mbufs, they are converted to a
chain of mapped mbufs (using sf_bufs to provide the mapping) in
ip_output or ip6_output. If an unmapped mbuf requires software
checksums, it is also converted to a chain of mapped mbufs before
computing the checksum.
Submitted by: gallatin (earlier version)
Reviewed by: gallatin, hselasky, rrs
Discussed with: ae, kp (firewalls)
Relnotes: yes
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20616
As of r340465 all consumers use sbsndptr_adv and sbsndptr_noadv
Reviewed by: gallatin
Approved by: krion (mentor)
Differential Revision: https://reviews.freebsd.org/D17998
sosend_generic() performs an initial comparison of the amount of data
(including control messages) to be transmitted with the send buffer
size. When transmitting on a unix socket, we then compare the amount
of data being sent with the amount of space in the receive buffer size;
if insufficient space is available, sbappendcontrol() returns an error
and the data is lost. This is easily triggered by sending control
messages together with an amount of data roughly equal to the send
buffer size, since the control message size may change in uipc_send()
as file descriptors are internalized.
Fix the problem by removing the space check in sbappendcontrol(),
whose only consumer is the unix sockets code. The stream sockets code
uses the SB_STOP mechanism to ensure that senders will block if the
receive buffer fills up.
PR: 181741
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D16515
Rack includes the following features:
- A different SACK processing scheme (the old sack structures are not used).
- RACK (Recent acknowledgment) where counting dup-acks is no longer done
instead time is used to knwo when to retransmit. (see the I-D)
- TLP (Tail Loss Probe) where we will probe for tail-losses to attempt
to try not to take a retransmit time-out. (see the I-D)
- Burst mitigation using TCPHTPS
- PRR (partial rate reduction) see the RFC.
Once built into your kernel, you can select this stack by either
socket option with the name of the stack is "rack" or by setting
the global sysctl so the default is rack.
Note that any connection that does not support SACK will be kicked
back to the "default" base FreeBSD stack (currently known as "default").
To build this into your kernel you will need to enable in your
kernel:
makeoptions WITH_EXTRA_TCP_STACKS=1
options TCPHPTS
Sponsored by: Netflix Inc.
Differential Revision: https://reviews.freebsd.org/D15525
Mainly focus on files that use BSD 3-Clause license.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
via soisdisconnected(), and in the earlier unlock earlier to avoid lock
recursion.
This fixes a situation when a socket on accept queue is reset before being
accepted.
Reported by: Jason Eggleston <jeggleston llnw.com>
It distinguishes between data flow sockets and listening sockets, and
in case of the latter doesn't change resource limits, since listening
sockets don't hold any buffers, they only carry values to be inherited
by their children.
o Separate fields of struct socket that belong to listening from
fields that belong to normal dataflow, and unionize them. This
shrinks the structure a bit.
- Take out selinfo's from the socket buffers into the socket. The
first reason is to support braindamaged scenario when a socket is
added to kevent(2) and then listen(2) is cast on it. The second
reason is that there is future plan to make socket buffers pluggable,
so that for a dataflow socket a socket buffer can be changed, and
in this case we also want to keep same selinfos through the lifetime
of a socket.
- Remove struct struct so_accf. Since now listening stuff no longer
affects struct socket size, just move its fields into listening part
of the union.
- Provide sol_upcall field and enforce that so_upcall_set() may be called
only on a dataflow socket, which has buffers, and for listening sockets
provide solisten_upcall_set().
o Remove ACCEPT_LOCK() global.
- Add a mutex to socket, to be used instead of socket buffer lock to lock
fields of struct socket that don't belong to a socket buffer.
- Allow to acquire two socket locks, but the first one must belong to a
listening socket.
- Make soref()/sorele() to use atomic(9). This allows in some situations
to do soref() without owning socket lock. There is place for improvement
here, it is possible to make sorele() also to lock optionally.
- Most protocols aren't touched by this change, except UNIX local sockets.
See below for more information.
o Reduce copy-and-paste in kernel modules that accept connections from
listening sockets: provide function solisten_dequeue(), and use it in
the following modules: ctl(4), iscsi(4), ng_btsocket(4), ng_ksocket(4),
infiniband, rpc.
o UNIX local sockets.
- Removal of ACCEPT_LOCK() global uncovered several races in the UNIX
local sockets. Most races exist around spawning a new socket, when we
are connecting to a local listening socket. To cover them, we need to
hold locks on both PCBs when spawning a third one. This means holding
them across sonewconn(). This creates a LOR between pcb locks and
unp_list_lock.
- To fix the new LOR, abandon the global unp_list_lock in favor of global
unp_link_lock. Indeed, separating these two locks didn't provide us any
extra parralelism in the UNIX sockets.
- Now call into uipc_attach() may happen with unp_link_lock hold if, we
are accepting, or without unp_link_lock in case if we are just creating
a socket.
- Another problem in UNIX sockets is that uipc_close() basicly did nothing
for a listening socket. The vnode remained opened for connections. This
is fixed by removing vnode in uipc_close(). Maybe the right way would be
to do it for all sockets (not only listening), simply move the vnode
teardown from uipc_detach() to uipc_close()?
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D9770
This happens when closing a socket with upcall, and trace is: soclose()->
... protocol ... -> soisdisconnected() -> socantrcvmore_locked() ->
sowakeup() -> soisconnected().
Right now this case is innocent for two reasons. First, soisconnected()
doesn't clear SS_ISDISCONNECTED flag. Second, the mutex to lock the
socket is the socket receive buffer mutex, and sodisconnected() first
disables the receive buffer. But in future code, the mutex to lock
socket is different to buffer mutex, and we would get undesired mutex
recursion.
The fix is to check SS_ISDISCONNECTED flag before calling upcall.
do for streaming sockets.
And do more cleanup in the sbappendaddr_locked_internal() to prevent
leak information from existing mbuf to the one, that will be possible
created later by netgraph.
Suggested by: glebius
Tested by: Irina Liakh <spell at itl ua>
MFC after: 1 week
stuck spinning at 100% cpu around sbcut_internal(). Inside
sbflush_internal(), sb_ccc reached to about 4GB and before passing it
to sbcut_internal(), we type-cast it from uint to int making it -ve.
The root cause of sockbuf growing this large is unknown. Correct fix
is also not clear but based on mailing list discussions, adding
KASSERTs to panic instead of looping endlessly.
Reviewed by: glebius
Sponsored by: Limelight Networks
improve cancellation robustness.
Introduce a new file operation, fo_aio_queue, which is responsible for
queueing and completing an asynchronous I/O request for a given file.
The AIO subystem now exports library of routines to manipulate AIO
requests as well as the ability to run a handler function in the
"default" pool of AIO daemons to service a request.
A default implementation for file types which do not include an
fo_aio_queue method queues requests to the "default" pool invoking the
fo_read or fo_write methods as before.
The AIO subsystem permits file types to install a private "cancel"
routine when a request is queued to permit safe dequeueing and cleanup
of cancelled requests.
Sockets now use their own pool of AIO daemons and service per-socket
requests in FIFO order. Socket requests will not block indefinitely
permitting timely cancellation of all requests.
Due to the now-tight coupling of the AIO subsystem with file types,
the AIO subsystem is now a standard part of all kernels. The VFS_AIO
kernel option and aio.ko module are gone.
Many file types may block indefinitely in their fo_read or fo_write
callbacks resulting in a hung AIO daemon. This can result in hung
user processes (when processes attempt to cancel all outstanding
requests during exit) or a hung system. To protect against this, AIO
requests are only permitted for known "safe" files by default. AIO
requests for all file types can be enabled by setting the new
vfs.aio.enable_usafe sysctl to a non-zero value. The AIO tests have
been updated to skip operations on unsafe file types if the sysctl is
zero.
Currently, AIO requests on sockets and raw disks are considered safe
and are enabled by default. aio_mlock() is also enabled by default.
Reviewed by: cem, jilles
Discussed with: kib (earlier version)
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D5289
sbappendstream() does. Although, M_NOTREADY may appear only on SOCK_STREAM
sockets, due to sendfile(2) supporting only the latter, there is a corner
case of AF_UNIX/SOCK_STREAM socket, that still uses records for the sake
of control data, albeit being stream socket.
Provide private version of m_clrprotoflags(), which understands PRUS_NOTREADY,
similar to m_demote().
Use the same scheme implemented to manage credentials.
Code needing to look at process's credentials (as opposed to thred's) is
provided with *_proc variants of relevant functions.
Places which possibly had to take the proc lock anyway still use the proc
pointer to access limits.
why there could appear a zero-sized mbufs in socket buffers.
A proper fix would be to divorce record socket buffers and stream
socket buffers, and divorce pru_send that accepts normal data from
pru_send that accepts control data.
in sbappend_locked() and sbappendrecord_locked().
This is a quick fix to the panic introduced by r274712.
A proper solution should be to make sosend_generic() avoid calling
pru_send() with NULL mbuf for the protocols that do not understand
control messages. Those protocols that understand control messages,
should be able to receive NULL mbuf, if control is non-NULL.
sending not ready data:
o Add new flag to pru_send() flags - PRUS_NOTREADY.
o Add new protocol method pru_ready().
Sponsored by: Nginx, Inc.
Sponsored by: Netflix
o Introduce a notion of "not ready" mbufs in socket buffers. These
mbufs are now being populated by some I/O in background and are
referenced outside. This forces following implications:
- An mbuf which is "not ready" can't be taken out of the buffer.
- An mbuf that is behind a "not ready" in the queue neither.
- If sockbet buffer is flushed, then "not ready" mbufs shouln't be
freed.
o In struct sockbuf the sb_cc field is split into sb_ccc and sb_acc.
The sb_ccc stands for ""claimed character count", or "committed
character count". And the sb_acc is "available character count".
Consumers of socket buffer API shouldn't already access them directly,
but use sbused() and sbavail() respectively.
o Not ready mbufs are marked with M_NOTREADY, and ready but blocked ones
with M_BLOCKED.
o New field sb_fnrdy points to the first not ready mbuf, to avoid linear
search.
o New function sbready() is provided to activate certain amount of mbufs
in a socket buffer.
A special note on SCTP:
SCTP has its own sockbufs. Unfortunately, FreeBSD stack doesn't yet
allow protocol specific sockbufs. Thus, SCTP does some hacks to make
itself compatible with FreeBSD: it manages sockbufs on its own, but keeps
sb_cc updated to inform the stack of amount of data in them. The new
notion of "not ready" data isn't supported by SCTP. Instead, only a
mechanical substitute is done: s/sb_cc/sb_ccc/.
A proper solution would be to take away struct sockbuf from struct
socket and allow protocols to implement their own socket buffers, like
SCTP already does. This was discussed with rrs@.
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
The current TSO limitation feature only takes the total number of
bytes in an mbuf chain into account and does not limit by the number
of mbufs in a chain. Some kinds of hardware is limited by two
factors. One is the fragment length and the second is the fragment
count. Both of these limits need to be taken into account when doing
TSO. Else some kinds of hardware might have to drop completely valid
mbuf chains because they cannot loaded into the given hardware's DMA
engine. The new way of doing TSO limitation has been made backwards
compatible as input from other FreeBSD developers and will use
defaults for values not set.
Reviewed by: adrian, rmacklem
Sponsored by: Mellanox Technologies
MFC after: 1 week
buffers drop packets". It was caused by a check for the space available
in a sockbuf, but it was checking the wrong sockbuf.
sys/sys/sockbuf.h
sys/kern/uipc_sockbuf.c
Add sbappendaddr_nospacecheck_locked(), which is just like
sbappendaddr_locked but doesn't validate the receiving socket's
space. Factor out common code into sbappendaddr_locked_internal().
We shouldn't simply make sbappendaddr_locked check the space and
then call sbappendaddr_nospacecheck_locked, because that would cause
the O(n) function m_length to be called twice.
sys/kern/uipc_usrreq.c
Use sbappendaddr_nospacecheck_locked for SOCK_SEQPACKET sockets,
because the receiving sockbuf's size limit is irrelevant.
tests/sys/kern/unix_seqpacket_test.c
Now that 185813 is fixed, pipe_128k_8k fails intermittently due to
185812. Make it fail every time by adding a usleep after starting
the writer thread and before starting the reader thread in
test_pipe. That gives the writer time to fill up its send buffer.
Also, clear the expected failure message due to 185813. It actually
said "185812", but that was a typo.
PR: kern/185813
Reviewed by: silence from freebsd-net@ and rwatson@
MFC after: 3 weeks
Sponsored by: Spectra Logic Corporation
