I edited the original change to retain the use of arc4random() as a seed for
the hashing as a very basic defense against intentional lagg port selection.
The author's original commit message (edited slightly):
sys/net/ieee8023ad_lacp.c
sys/net/if_lagg.c
In lagg_hashmbuf, use the FNV hash instead of the old
hash32_buf. The hash32 family of functions operate one octet
at a time, and when run on a string s of length n, their output
is equivalent to :
----- i=n-1
\
n \ (n-i-1) 32
( seed^ + / 33^ * s[i] ) % 2^
/
----- i=0
The problem is that the last five bytes of input don't get
multiplied by sufficiently many powers of 33 to rollover 2^32.
That means that changing the last few bytes (but obviously not
the very last) of input will always change the value of the
hash by a multiple of 33. In the case of lagg_hashmbuf() with
ipv4 input, the last four bytes are the TCP or UDP port
numbers. Since the output of lagg_hashmbuf is always taken
modulo the port count, and 3 is a common port count for a lagg,
that's bad. It means that the UDP or TCP source port will
never affect which lagg member is selected on a 3-port lagg.
At 10Gbps, I was not able to measure any difference in CPU
consumption between the old and new hash.
Submitted by: asomers (original commit)
Reviewed by: emaste, glebius
MFC after: 1 week
Sponsored by: Spectra Logic
MFSpectraBSD: 1001723 on 2013/08/28 (original)
1114258 on 2015/01/22 (edit)
from the FreeBSD network code. The flag is still kept around in the
"sys/mbuf.h" header file, but does no longer have any users. Instead
the "m_pkthdr.rsstype" field in the mbuf structure is now used to
decide the meaning of the "m_pkthdr.flowid" field. To modify the
"m_pkthdr.rsstype" field please use the existing "M_HASHTYPE_XXX"
macros as defined in the "sys/mbuf.h" header file.
This patch introduces new behaviour in the transmit direction.
Previously network drivers checked if "M_FLOWID" was set in "m_flags"
before using the "m_pkthdr.flowid" field. This check has now now been
replaced by checking if "M_HASHTYPE_GET(m)" is different from
"M_HASHTYPE_NONE". In the future more hashtypes will be added, for
example hashtypes for hardware dedicated flows.
"M_HASHTYPE_OPAQUE" indicates that the "m_pkthdr.flowid" value is
valid and has no particular type. This change removes the need for an
"if" statement in TCP transmit code checking for the presence of a
valid flowid value. The "if" statement mentioned above is now a direct
variable assignment which is then later checked by the respective
network drivers like before.
Additional notes:
- The SCTP code changes will be committed as a separate patch.
- Removal of the "M_FLOWID" flag will also be done separately.
- The FreeBSD version has been bumped.
MFC after: 1 month
Sponsored by: Mellanox Technologies
LOR of softc rmlock in iflladdr_event handlers.
- Call if_delmulti_ifma() after LACP_UNLOCK(). This fixes another LOR.
- Fix a panic in lacp_transit_expire().
- Fix a panic in lagg_input() upon shutting down a port.
if_lagg(4) interfaces which were cloned in a vnet jail.
Sysctl nodes which are dynamically generated for each cloned interface
(net.link.lagg.N.*) have been removed, and use_flowid and flowid_shift
ifconfig(8) parameters have been added instead. Flags and per-interface
statistics counters are displayed in "ifconfig -v".
CR: D842
then drop lock, run the attach routines, and then set it to specific
proto. This removes tons of WITNESS warnings.
- Make lagg protocol attach handlers not failing and allocate memory
with M_WAITOK.
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
These changes prevent sysctl(8) from returning proper output,
such as:
1) no output from sysctl(8)
2) erroneously returning ENOMEM with tools like truss(1)
or uname(1)
truss: can not get etype: Cannot allocate memory
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.
Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.
MFC after: 2 weeks
Sponsored by: Mellanox Technologies
The thread that is destroying the lagg has already set sc->sc_psc=NULL when
the "ifconfig -am" thread gets to lacp_req(). It tries to dereference
sc->sc_psc and panics. The solution is for lacp_req() to check the value of
sc->sc_psc. If NULL, harmlessly return an lacp_opreq structure full of
zeros. Full details in GNATS.
PR: kern/189003
Reviewed by: timeout on freebsd-net@
MFC after: 3 weeks
Sponsored by: Spectra Logic Corporation
callback providers. link_init_sdl() function can be used to
fill most of the parameters. Use caller stack instead of
allocation / freing memory for each request. Do not drop support
for extra-long (probably non-existing) link-layer protocols by
introducing link_alloc_sdl() (used by if_resolvemulti() callback)
and link_free_sdl() (used by caller).
Since this change breaks KBI, MFC requires slightly different approach
(link_init_sdl() auto-allocating buffer if necessary to handle cases
with unmodified if_resolvemulti() callers).
MFC after: 2 weeks
bits of the flowid as each other, resulting in a poor distribution of
packets among queues in certain cases. Work around this by adding a
set of sysctls for controlling a bit-shift on the flowid when doing
multi-port aggrigation in lagg and lacp. By default, lagg/lacp will
now use bits 16 and higher instead of 0 and higher.
Reviewed by: max
Obtained from: Netflix
MFC after: 3 days
to this event, adding if_var.h to files that do need it. Also, include
all includes that now are included due to implicit pollution via if_var.h
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
sysctl tree.
* Create a net.link.lagg.X.lacp node
* Add a debug node under that for tx_test and rx_test
* Add lacp_strict_mode, defaulting to 1
tx_test and rx_test are still a bitmap of unit numbers for now.
At some point it would be nice to create child nodes of the lagg bundle
for each sub-interface, and then populate those with various knobs
and statistics.
Sponsored by: Netflix
additions.
* Add some new tracing events to aid in debugging.
* Add in a debugging mode to drop transmit and received frames, specifically
to test whether seeing or hearing heartbeats correctly cause LACP to
drop the port.
* Add in (and make default) a strict LACP mode, which requires the
heartbeat on a port to be heard before it's used. Sometimes vendor ports
will hang but the link layer stays up, resulting in hung traffic.
* Add logging the number of link status flaps, again to aid in debugging
badly behaving switch ports.
* Calculate the lagg interface port speed as the multiple of the
configured ports, rather than the largest.
Obtained from: Netflix
MFC after: 2 weeks
the traffic flow, this may not be the case giving poor traffic distribution.
Add a sysctl which allows us to fall back to our own flow hash code.
PR: kern/164901
Submitted by: Eugene Grosbein
MFC after: 1 week
this means that it no longer grabs the lagg rwlock. Use two port table arrays
which list the active ports for Tx and switch between them with an atomic op.
Now the lagg rwlock is only exclusively locked for management (ioctls) and
queuing of lacp control frames isnt needed.
of each port and any further packets are blocked, when the all the marker frames
have been returned to us from the remote network device then we can be sure
that all interface queues are empty.
This is needed when a port is added or removed from the aggregation since it
will affect the hash based distribution, if the queues are not empty then a
packet from an existing connection may be placed on a different interface and
arrive out of order. This was previously achieved by suppressing transmission for
1 second, now that there is an active feedback this timeout as been increased
to 3 seconds and used as a fallback.
The name trunk is misused as the networking term trunk means carrying multiple
VLANs over a single connection. The IEEE standard for link aggregation (802.3
section 3) does not talk about 'trunk' at all while it is used throughout IEEE
802.1Q in describing vlans.
The lagg(4) driver provides link aggregation, failover and fault tolerance.
Discussed on: current@
tolerance. This driver allows aggregation of multiple network interfaces as
one virtual interface using a number of different protocols/algorithms.
failover - Sends traffic through the secondary port if the master becomes
inactive.
fec - Supports Cisco Fast EtherChannel.
lacp - Supports the IEEE 802.3ad Link Aggregation Control Protocol
(LACP) and the Marker Protocol.
loadbalance - Static loadbalancing using an outgoing hash.
roundrobin - Distributes outgoing traffic using a round-robin scheduler
through all active ports.
This code was obtained from OpenBSD and this also includes 802.3ad LACP support
from agr(4) in NetBSD.
