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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/core-api/genalloc.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/core-api/genalloc.rst')
-rw-r--r-- | Documentation/core-api/genalloc.rst | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/Documentation/core-api/genalloc.rst b/Documentation/core-api/genalloc.rst new file mode 100644 index 000000000..a5af2cbf5 --- /dev/null +++ b/Documentation/core-api/genalloc.rst @@ -0,0 +1,144 @@ +The genalloc/genpool subsystem +============================== + +There are a number of memory-allocation subsystems in the kernel, each +aimed at a specific need. Sometimes, however, a kernel developer needs to +implement a new allocator for a specific range of special-purpose memory; +often that memory is located on a device somewhere. The author of the +driver for that device can certainly write a little allocator to get the +job done, but that is the way to fill the kernel with dozens of poorly +tested allocators. Back in 2005, Jes Sorensen lifted one of those +allocators from the sym53c8xx_2 driver and posted_ it as a generic module +for the creation of ad hoc memory allocators. This code was merged +for the 2.6.13 release; it has been modified considerably since then. + +.. _posted: https://lwn.net/Articles/125842/ + +Code using this allocator should include <linux/genalloc.h>. The action +begins with the creation of a pool using one of: + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_create + +.. kernel-doc:: lib/genalloc.c + :functions: devm_gen_pool_create + +A call to gen_pool_create() will create a pool. The granularity of +allocations is set with min_alloc_order; it is a log-base-2 number like +those used by the page allocator, but it refers to bytes rather than pages. +So, if min_alloc_order is passed as 3, then all allocations will be a +multiple of eight bytes. Increasing min_alloc_order decreases the memory +required to track the memory in the pool. The nid parameter specifies +which NUMA node should be used for the allocation of the housekeeping +structures; it can be -1 if the caller doesn't care. + +The "managed" interface devm_gen_pool_create() ties the pool to a +specific device. Among other things, it will automatically clean up the +pool when the given device is destroyed. + +A pool is shut down with: + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_destroy + +It's worth noting that, if there are still allocations outstanding from the +given pool, this function will take the rather extreme step of invoking +BUG(), crashing the entire system. You have been warned. + +A freshly created pool has no memory to allocate. It is fairly useless in +that state, so one of the first orders of business is usually to add memory +to the pool. That can be done with one of: + +.. kernel-doc:: include/linux/genalloc.h + :functions: gen_pool_add + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_add_owner + +A call to gen_pool_add() will place the size bytes of memory +starting at addr (in the kernel's virtual address space) into the given +pool, once again using nid as the node ID for ancillary memory allocations. +The gen_pool_add_virt() variant associates an explicit physical +address with the memory; this is only necessary if the pool will be used +for DMA allocations. + +The functions for allocating memory from the pool (and putting it back) +are: + +.. kernel-doc:: include/linux/genalloc.h + :functions: gen_pool_alloc + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_dma_alloc + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_free_owner + +As one would expect, gen_pool_alloc() will allocate size< bytes +from the given pool. The gen_pool_dma_alloc() variant allocates +memory for use with DMA operations, returning the associated physical +address in the space pointed to by dma. This will only work if the memory +was added with gen_pool_add_virt(). Note that this function +departs from the usual genpool pattern of using unsigned long values to +represent kernel addresses; it returns a void * instead. + +That all seems relatively simple; indeed, some developers clearly found it +to be too simple. After all, the interface above provides no control over +how the allocation functions choose which specific piece of memory to +return. If that sort of control is needed, the following functions will be +of interest: + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_alloc_algo_owner + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_set_algo + +Allocations with gen_pool_alloc_algo() specify an algorithm to be +used to choose the memory to be allocated; the default algorithm can be set +with gen_pool_set_algo(). The data value is passed to the +algorithm; most ignore it, but it is occasionally needed. One can, +naturally, write a special-purpose algorithm, but there is a fair set +already available: + +- gen_pool_first_fit is a simple first-fit allocator; this is the default + algorithm if none other has been specified. + +- gen_pool_first_fit_align forces the allocation to have a specific + alignment (passed via data in a genpool_data_align structure). + +- gen_pool_first_fit_order_align aligns the allocation to the order of the + size. A 60-byte allocation will thus be 64-byte aligned, for example. + +- gen_pool_best_fit, as one would expect, is a simple best-fit allocator. + +- gen_pool_fixed_alloc allocates at a specific offset (passed in a + genpool_data_fixed structure via the data parameter) within the pool. + If the indicated memory is not available the allocation fails. + +There is a handful of other functions, mostly for purposes like querying +the space available in the pool or iterating through chunks of memory. +Most users, however, should not need much beyond what has been described +above. With luck, wider awareness of this module will help to prevent the +writing of special-purpose memory allocators in the future. + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_virt_to_phys + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_for_each_chunk + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_has_addr + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_avail + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_size + +.. kernel-doc:: lib/genalloc.c + :functions: gen_pool_get + +.. kernel-doc:: lib/genalloc.c + :functions: of_gen_pool_get |