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author | 2023-02-21 18:24:12 -0800 | |
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committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/process/management-style.rst | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski:
"Core:
- Add dedicated kmem_cache for typical/small skb->head, avoid having
to access struct page at kfree time, and improve memory use.
- Introduce sysctl to set default RPS configuration for new netdevs.
- Define Netlink protocol specification format which can be used to
describe messages used by each family and auto-generate parsers.
Add tools for generating kernel data structures and uAPI headers.
- Expose all net/core sysctls inside netns.
- Remove 4s sleep in netpoll if carrier is instantly detected on
boot.
- Add configurable limit of MDB entries per port, and port-vlan.
- Continue populating drop reasons throughout the stack.
- Retire a handful of legacy Qdiscs and classifiers.
Protocols:
- Support IPv4 big TCP (TSO frames larger than 64kB).
- Add IP_LOCAL_PORT_RANGE socket option, to control local port range
on socket by socket basis.
- Track and report in procfs number of MPTCP sockets used.
- Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
manager.
- IPv6: don't check net.ipv6.route.max_size and rely on garbage
collection to free memory (similarly to IPv4).
- Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).
- ICMP: add per-rate limit counters.
- Add support for user scanning requests in ieee802154.
- Remove static WEP support.
- Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
reporting.
- WiFi 7 EHT channel puncturing support (client & AP).
BPF:
- Add a rbtree data structure following the "next-gen data structure"
precedent set by recently added linked list, that is, by using
kfunc + kptr instead of adding a new BPF map type.
- Expose XDP hints via kfuncs with initial support for RX hash and
timestamp metadata.
- Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
better support decap on GRE tunnel devices not operating in collect
metadata.
- Improve x86 JIT's codegen for PROBE_MEM runtime error checks.
- Remove the need for trace_printk_lock for bpf_trace_printk and
bpf_trace_vprintk helpers.
- Extend libbpf's bpf_tracing.h support for tracing arguments of
kprobes/uprobes and syscall as a special case.
- Significantly reduce the search time for module symbols by
livepatch and BPF.
- Enable cpumasks to be used as kptrs, which is useful for tracing
programs tracking which tasks end up running on which CPUs in
different time intervals.
- Add support for BPF trampoline on s390x and riscv64.
- Add capability to export the XDP features supported by the NIC.
- Add __bpf_kfunc tag for marking kernel functions as kfuncs.
- Add cgroup.memory=nobpf kernel parameter option to disable BPF
memory accounting for container environments.
Netfilter:
- Remove the CLUSTERIP target. It has been marked as obsolete for
years, and we still have WARN splats wrt races of the out-of-band
/proc interface installed by this target.
- Add 'destroy' commands to nf_tables. They are identical to the
existing 'delete' commands, but do not return an error if the
referenced object (set, chain, rule...) did not exist.
Driver API:
- Improve cpumask_local_spread() locality to help NICs set the right
IRQ affinity on AMD platforms.
- Separate C22 and C45 MDIO bus transactions more clearly.
- Introduce new DCB table to control DSCP rewrite on egress.
- Support configuration of Physical Layer Collision Avoidance (PLCA)
Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
shared medium Ethernet.
- Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
preemption of low priority frames by high priority frames.
- Add support for controlling MACSec offload using netlink SET.
- Rework devlink instance refcounts to allow registration and
de-registration under the instance lock. Split the code into
multiple files, drop some of the unnecessarily granular locks and
factor out common parts of netlink operation handling.
- Add TX frame aggregation parameters (for USB drivers).
- Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
messages with notifications for debug.
- Allow offloading of UDP NEW connections via act_ct.
- Add support for per action HW stats in TC.
- Support hardware miss to TC action (continue processing in SW from
a specific point in the action chain).
- Warn if old Wireless Extension user space interface is used with
modern cfg80211/mac80211 drivers. Do not support Wireless
Extensions for Wi-Fi 7 devices at all. Everyone should switch to
using nl80211 interface instead.
- Improve the CAN bit timing configuration. Use extack to return
error messages directly to user space, update the SJW handling,
including the definition of a new default value that will benefit
CAN-FD controllers, by increasing their oscillator tolerance.
New hardware / drivers:
- Ethernet:
- nVidia BlueField-3 support (control traffic driver)
- Ethernet support for imx93 SoCs
- Motorcomm yt8531 gigabit Ethernet PHY
- onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
- Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
- Amlogic gxl MDIO mux
- WiFi:
- RealTek RTL8188EU (rtl8xxxu)
- Qualcomm Wi-Fi 7 devices (ath12k)
- CAN:
- Renesas R-Car V4H
Drivers:
- Bluetooth:
- Set Per Platform Antenna Gain (PPAG) for Intel controllers.
- Ethernet NICs:
- Intel (1G, igc):
- support TSN / Qbv / packet scheduling features of i226 model
- Intel (100G, ice):
- use GNSS subsystem instead of TTY
- multi-buffer XDP support
- extend support for GPIO pins to E823 devices
- nVidia/Mellanox:
- update the shared buffer configuration on PFC commands
- implement PTP adjphase function for HW offset control
- TC support for Geneve and GRE with VF tunnel offload
- more efficient crypto key management method
- multi-port eswitch support
- Netronome/Corigine:
- add DCB IEEE support
- support IPsec offloading for NFP3800
- Freescale/NXP (enetc):
- support XDP_REDIRECT for XDP non-linear buffers
- improve reconfig, avoid link flap and waiting for idle
- support MAC Merge layer
- Other NICs:
- sfc/ef100: add basic devlink support for ef100
- ionic: rx_push mode operation (writing descriptors via MMIO)
- bnxt: use the auxiliary bus abstraction for RDMA
- r8169: disable ASPM and reset bus in case of tx timeout
- cpsw: support QSGMII mode for J721e CPSW9G
- cpts: support pulse-per-second output
- ngbe: add an mdio bus driver
- usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
- r8152: handle devices with FW with NCM support
- amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
- virtio-net: support multi buffer XDP
- virtio/vsock: replace virtio_vsock_pkt with sk_buff
- tsnep: XDP support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add support for latency TLV (in FW control messages)
- Microchip (sparx5):
- separate explicit and implicit traffic forwarding rules, make
the implicit rules always active
- add support for egress DSCP rewrite
- IS0 VCAP support (Ingress Classification)
- IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
etc.)
- ES2 VCAP support (Egress Access Control)
- support for Per-Stream Filtering and Policing (802.1Q,
8.6.5.1)
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- add MAB (port auth) offload support
- enable PTP receive for mv88e6390
- NXP (ocelot):
- support MAC Merge layer
- support for the the vsc7512 internal copper phys
- Microchip:
- lan9303: convert to PHYLINK
- lan966x: support TC flower filter statistics
- lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
- lan937x: support Credit Based Shaper configuration
- ksz9477: support Energy Efficient Ethernet
- other:
- qca8k: convert to regmap read/write API, use bulk operations
- rswitch: Improve TX timestamp accuracy
- Intel WiFi (iwlwifi):
- EHT (Wi-Fi 7) rate reporting
- STEP equalizer support: transfer some STEP (connection to radio
on platforms with integrated wifi) related parameters from the
BIOS to the firmware.
- Qualcomm 802.11ax WiFi (ath11k):
- IPQ5018 support
- Fine Timing Measurement (FTM) responder role support
- channel 177 support
- MediaTek WiFi (mt76):
- per-PHY LED support
- mt7996: EHT (Wi-Fi 7) support
- Wireless Ethernet Dispatch (WED) reset support
- switch to using page pool allocator
- RealTek WiFi (rtw89):
- support new version of Bluetooth co-existance
- Mobile:
- rmnet: support TX aggregation"
* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
page_pool: add a comment explaining the fragment counter usage
net: ethtool: fix __ethtool_dev_mm_supported() implementation
ethtool: pse-pd: Fix double word in comments
xsk: add linux/vmalloc.h to xsk.c
sefltests: netdevsim: wait for devlink instance after netns removal
selftest: fib_tests: Always cleanup before exit
net/mlx5e: Align IPsec ASO result memory to be as required by hardware
net/mlx5e: TC, Set CT miss to the specific ct action instance
net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
net/mlx5: Refactor tc miss handling to a single function
net/mlx5: Kconfig: Make tc offload depend on tc skb extension
net/sched: flower: Support hardware miss to tc action
net/sched: flower: Move filter handle initialization earlier
net/sched: cls_api: Support hardware miss to tc action
net/sched: Rename user cookie and act cookie
sfc: fix builds without CONFIG_RTC_LIB
sfc: clean up some inconsistent indentings
net/mlx4_en: Introduce flexible array to silence overflow warning
net: lan966x: Fix possible deadlock inside PTP
net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
...
Diffstat (limited to 'Documentation/process/management-style.rst')
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1 files changed, 290 insertions, 0 deletions
diff --git a/Documentation/process/management-style.rst b/Documentation/process/management-style.rst new file mode 100644 index 000000000..dfbc69bf4 --- /dev/null +++ b/Documentation/process/management-style.rst @@ -0,0 +1,290 @@ +.. _managementstyle: + +Linux kernel management style +============================= + +This is a short document describing the preferred (or made up, depending +on who you ask) management style for the linux kernel. It's meant to +mirror the :ref:`process/coding-style.rst <codingstyle>` document to some +degree, and mainly written to avoid answering [#f1]_ the same (or similar) +questions over and over again. + +Management style is very personal and much harder to quantify than +simple coding style rules, so this document may or may not have anything +to do with reality. It started as a lark, but that doesn't mean that it +might not actually be true. You'll have to decide for yourself. + +Btw, when talking about "kernel manager", it's all about the technical +lead persons, not the people who do traditional management inside +companies. If you sign purchase orders or you have any clue about the +budget of your group, you're almost certainly not a kernel manager. +These suggestions may or may not apply to you. + +First off, I'd suggest buying "Seven Habits of Highly Effective +People", and NOT read it. Burn it, it's a great symbolic gesture. + +.. [#f1] This document does so not so much by answering the question, but by + making it painfully obvious to the questioner that we don't have a clue + to what the answer is. + +Anyway, here goes: + +.. _decisions: + +1) Decisions +------------ + +Everybody thinks managers make decisions, and that decision-making is +important. The bigger and more painful the decision, the bigger the +manager must be to make it. That's very deep and obvious, but it's not +actually true. + +The name of the game is to **avoid** having to make a decision. In +particular, if somebody tells you "choose (a) or (b), we really need you +to decide on this", you're in trouble as a manager. The people you +manage had better know the details better than you, so if they come to +you for a technical decision, you're screwed. You're clearly not +competent to make that decision for them. + +(Corollary:if the people you manage don't know the details better than +you, you're also screwed, although for a totally different reason. +Namely that you are in the wrong job, and that **they** should be managing +your brilliance instead). + +So the name of the game is to **avoid** decisions, at least the big and +painful ones. Making small and non-consequential decisions is fine, and +makes you look like you know what you're doing, so what a kernel manager +needs to do is to turn the big and painful ones into small things where +nobody really cares. + +It helps to realize that the key difference between a big decision and a +small one is whether you can fix your decision afterwards. Any decision +can be made small by just always making sure that if you were wrong (and +you **will** be wrong), you can always undo the damage later by +backtracking. Suddenly, you get to be doubly managerial for making +**two** inconsequential decisions - the wrong one **and** the right one. + +And people will even see that as true leadership (*cough* bullshit +*cough*). + +Thus the key to avoiding big decisions becomes to just avoiding to do +things that can't be undone. Don't get ushered into a corner from which +you cannot escape. A cornered rat may be dangerous - a cornered manager +is just pitiful. + +It turns out that since nobody would be stupid enough to ever really let +a kernel manager have huge fiscal responsibility **anyway**, it's usually +fairly easy to backtrack. Since you're not going to be able to waste +huge amounts of money that you might not be able to repay, the only +thing you can backtrack on is a technical decision, and there +back-tracking is very easy: just tell everybody that you were an +incompetent nincompoop, say you're sorry, and undo all the worthless +work you had people work on for the last year. Suddenly the decision +you made a year ago wasn't a big decision after all, since it could be +easily undone. + +It turns out that some people have trouble with this approach, for two +reasons: + + - admitting you were an idiot is harder than it looks. We all like to + maintain appearances, and coming out in public to say that you were + wrong is sometimes very hard indeed. + - having somebody tell you that what you worked on for the last year + wasn't worthwhile after all can be hard on the poor lowly engineers + too, and while the actual **work** was easy enough to undo by just + deleting it, you may have irrevocably lost the trust of that + engineer. And remember: "irrevocable" was what we tried to avoid in + the first place, and your decision ended up being a big one after + all. + +Happily, both of these reasons can be mitigated effectively by just +admitting up-front that you don't have a friggin' clue, and telling +people ahead of the fact that your decision is purely preliminary, and +might be the wrong thing. You should always reserve the right to change +your mind, and make people very **aware** of that. And it's much easier +to admit that you are stupid when you haven't **yet** done the really +stupid thing. + +Then, when it really does turn out to be stupid, people just roll their +eyes and say "Oops, not again". + +This preemptive admission of incompetence might also make the people who +actually do the work also think twice about whether it's worth doing or +not. After all, if **they** aren't certain whether it's a good idea, you +sure as hell shouldn't encourage them by promising them that what they +work on will be included. Make them at least think twice before they +embark on a big endeavor. + +Remember: they'd better know more about the details than you do, and +they usually already think they have the answer to everything. The best +thing you can do as a manager is not to instill confidence, but rather a +healthy dose of critical thinking on what they do. + +Btw, another way to avoid a decision is to plaintively just whine "can't +we just do both?" and look pitiful. Trust me, it works. If it's not +clear which approach is better, they'll eventually figure it out. The +answer may end up being that both teams get so frustrated by the +situation that they just give up. + +That may sound like a failure, but it's usually a sign that there was +something wrong with both projects, and the reason the people involved +couldn't decide was that they were both wrong. You end up coming up +smelling like roses, and you avoided yet another decision that you could +have screwed up on. + + +2) People +--------- + +Most people are idiots, and being a manager means you'll have to deal +with it, and perhaps more importantly, that **they** have to deal with +**you**. + +It turns out that while it's easy to undo technical mistakes, it's not +as easy to undo personality disorders. You just have to live with +theirs - and yours. + +However, in order to prepare yourself as a kernel manager, it's best to +remember not to burn any bridges, bomb any innocent villagers, or +alienate too many kernel developers. It turns out that alienating people +is fairly easy, and un-alienating them is hard. Thus "alienating" +immediately falls under the heading of "not reversible", and becomes a +no-no according to :ref:`decisions`. + +There's just a few simple rules here: + + (1) don't call people d*ckheads (at least not in public) + (2) learn how to apologize when you forgot rule (1) + +The problem with #1 is that it's very easy to do, since you can say +"you're a d*ckhead" in millions of different ways [#f2]_, sometimes without +even realizing it, and almost always with a white-hot conviction that +you are right. + +And the more convinced you are that you are right (and let's face it, +you can call just about **anybody** a d*ckhead, and you often **will** be +right), the harder it ends up being to apologize afterwards. + +To solve this problem, you really only have two options: + + - get really good at apologies + - spread the "love" out so evenly that nobody really ends up feeling + like they get unfairly targeted. Make it inventive enough, and they + might even be amused. + +The option of being unfailingly polite really doesn't exist. Nobody will +trust somebody who is so clearly hiding their true character. + +.. [#f2] Paul Simon sang "Fifty Ways to Leave Your Lover", because quite + frankly, "A Million Ways to Tell a Developer They're a D*ckhead" doesn't + scan nearly as well. But I'm sure he thought about it. + + +3) People II - the Good Kind +---------------------------- + +While it turns out that most people are idiots, the corollary to that is +sadly that you are one too, and that while we can all bask in the secure +knowledge that we're better than the average person (let's face it, +nobody ever believes that they're average or below-average), we should +also admit that we're not the sharpest knife around, and there will be +other people that are less of an idiot than you are. + +Some people react badly to smart people. Others take advantage of them. + +Make sure that you, as a kernel maintainer, are in the second group. +Suck up to them, because they are the people who will make your job +easier. In particular, they'll be able to make your decisions for you, +which is what the game is all about. + +So when you find somebody smarter than you are, just coast along. Your +management responsibilities largely become ones of saying "Sounds like a +good idea - go wild", or "That sounds good, but what about xxx?". The +second version in particular is a great way to either learn something +new about "xxx" or seem **extra** managerial by pointing out something the +smarter person hadn't thought about. In either case, you win. + +One thing to look out for is to realize that greatness in one area does +not necessarily translate to other areas. So you might prod people in +specific directions, but let's face it, they might be good at what they +do, and suck at everything else. The good news is that people tend to +naturally gravitate back to what they are good at, so it's not like you +are doing something irreversible when you **do** prod them in some +direction, just don't push too hard. + + +4) Placing blame +---------------- + +Things will go wrong, and people want somebody to blame. Tag, you're it. + +It's not actually that hard to accept the blame, especially if people +kind of realize that it wasn't **all** your fault. Which brings us to the +best way of taking the blame: do it for someone else. You'll feel good +for taking the fall, they'll feel good about not getting blamed, and the +person who lost their whole 36GB porn-collection because of your +incompetence will grudgingly admit that you at least didn't try to weasel +out of it. + +Then make the developer who really screwed up (if you can find them) know +**in private** that they screwed up. Not just so they can avoid it in the +future, but so that they know they owe you one. And, perhaps even more +importantly, they're also likely the person who can fix it. Because, let's +face it, it sure ain't you. + +Taking the blame is also why you get to be manager in the first place. +It's part of what makes people trust you, and allow you the potential +glory, because you're the one who gets to say "I screwed up". And if +you've followed the previous rules, you'll be pretty good at saying that +by now. + + +5) Things to avoid +------------------ + +There's one thing people hate even more than being called "d*ckhead", +and that is being called a "d*ckhead" in a sanctimonious voice. The +first you can apologize for, the second one you won't really get the +chance. They likely will no longer be listening even if you otherwise +do a good job. + +We all think we're better than anybody else, which means that when +somebody else puts on airs, it **really** rubs us the wrong way. You may +be morally and intellectually superior to everybody around you, but +don't try to make it too obvious unless you really **intend** to irritate +somebody [#f3]_. + +Similarly, don't be too polite or subtle about things. Politeness easily +ends up going overboard and hiding the problem, and as they say, "On the +internet, nobody can hear you being subtle". Use a big blunt object to +hammer the point in, because you can't really depend on people getting +your point otherwise. + +Some humor can help pad both the bluntness and the moralizing. Going +overboard to the point of being ridiculous can drive a point home +without making it painful to the recipient, who just thinks you're being +silly. It can thus help get through the personal mental block we all +have about criticism. + +.. [#f3] Hint: internet newsgroups that are not directly related to your work + are great ways to take out your frustrations at other people. Write + insulting posts with a sneer just to get into a good flame every once in + a while, and you'll feel cleansed. Just don't crap too close to home. + + +6) Why me? +---------- + +Since your main responsibility seems to be to take the blame for other +peoples mistakes, and make it painfully obvious to everybody else that +you're incompetent, the obvious question becomes one of why do it in the +first place? + +First off, while you may or may not get screaming teenage girls (or +boys, let's not be judgmental or sexist here) knocking on your dressing +room door, you **will** get an immense feeling of personal accomplishment +for being "in charge". Never mind the fact that you're really leading +by trying to keep up with everybody else and running after them as fast +as you can. Everybody will still think you're the person in charge. + +It's a great job if you can hack it. |