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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
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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(). ...
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+.. _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.