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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 /kernel/locking/percpu-rwsem.c | |
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 '')
-rw-r--r-- | kernel/locking/percpu-rwsem.c | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c new file mode 100644 index 000000000..185bd1c90 --- /dev/null +++ b/kernel/locking/percpu-rwsem.c @@ -0,0 +1,282 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/atomic.h> +#include <linux/percpu.h> +#include <linux/wait.h> +#include <linux/lockdep.h> +#include <linux/percpu-rwsem.h> +#include <linux/rcupdate.h> +#include <linux/sched.h> +#include <linux/sched/task.h> +#include <linux/sched/debug.h> +#include <linux/errno.h> +#include <trace/events/lock.h> + +int __percpu_init_rwsem(struct percpu_rw_semaphore *sem, + const char *name, struct lock_class_key *key) +{ + sem->read_count = alloc_percpu(int); + if (unlikely(!sem->read_count)) + return -ENOMEM; + + rcu_sync_init(&sem->rss); + rcuwait_init(&sem->writer); + init_waitqueue_head(&sem->waiters); + atomic_set(&sem->block, 0); +#ifdef CONFIG_DEBUG_LOCK_ALLOC + debug_check_no_locks_freed((void *)sem, sizeof(*sem)); + lockdep_init_map(&sem->dep_map, name, key, 0); +#endif + return 0; +} +EXPORT_SYMBOL_GPL(__percpu_init_rwsem); + +void percpu_free_rwsem(struct percpu_rw_semaphore *sem) +{ + /* + * XXX: temporary kludge. The error path in alloc_super() + * assumes that percpu_free_rwsem() is safe after kzalloc(). + */ + if (!sem->read_count) + return; + + rcu_sync_dtor(&sem->rss); + free_percpu(sem->read_count); + sem->read_count = NULL; /* catch use after free bugs */ +} +EXPORT_SYMBOL_GPL(percpu_free_rwsem); + +static bool __percpu_down_read_trylock(struct percpu_rw_semaphore *sem) +{ + this_cpu_inc(*sem->read_count); + + /* + * Due to having preemption disabled the decrement happens on + * the same CPU as the increment, avoiding the + * increment-on-one-CPU-and-decrement-on-another problem. + * + * If the reader misses the writer's assignment of sem->block, then the + * writer is guaranteed to see the reader's increment. + * + * Conversely, any readers that increment their sem->read_count after + * the writer looks are guaranteed to see the sem->block value, which + * in turn means that they are guaranteed to immediately decrement + * their sem->read_count, so that it doesn't matter that the writer + * missed them. + */ + + smp_mb(); /* A matches D */ + + /* + * If !sem->block the critical section starts here, matched by the + * release in percpu_up_write(). + */ + if (likely(!atomic_read_acquire(&sem->block))) + return true; + + this_cpu_dec(*sem->read_count); + + /* Prod writer to re-evaluate readers_active_check() */ + rcuwait_wake_up(&sem->writer); + + return false; +} + +static inline bool __percpu_down_write_trylock(struct percpu_rw_semaphore *sem) +{ + if (atomic_read(&sem->block)) + return false; + + return atomic_xchg(&sem->block, 1) == 0; +} + +static bool __percpu_rwsem_trylock(struct percpu_rw_semaphore *sem, bool reader) +{ + if (reader) { + bool ret; + + preempt_disable(); + ret = __percpu_down_read_trylock(sem); + preempt_enable(); + + return ret; + } + return __percpu_down_write_trylock(sem); +} + +/* + * The return value of wait_queue_entry::func means: + * + * <0 - error, wakeup is terminated and the error is returned + * 0 - no wakeup, a next waiter is tried + * >0 - woken, if EXCLUSIVE, counted towards @nr_exclusive. + * + * We use EXCLUSIVE for both readers and writers to preserve FIFO order, + * and play games with the return value to allow waking multiple readers. + * + * Specifically, we wake readers until we've woken a single writer, or until a + * trylock fails. + */ +static int percpu_rwsem_wake_function(struct wait_queue_entry *wq_entry, + unsigned int mode, int wake_flags, + void *key) +{ + bool reader = wq_entry->flags & WQ_FLAG_CUSTOM; + struct percpu_rw_semaphore *sem = key; + struct task_struct *p; + + /* concurrent against percpu_down_write(), can get stolen */ + if (!__percpu_rwsem_trylock(sem, reader)) + return 1; + + p = get_task_struct(wq_entry->private); + list_del_init(&wq_entry->entry); + smp_store_release(&wq_entry->private, NULL); + + wake_up_process(p); + put_task_struct(p); + + return !reader; /* wake (readers until) 1 writer */ +} + +static void percpu_rwsem_wait(struct percpu_rw_semaphore *sem, bool reader) +{ + DEFINE_WAIT_FUNC(wq_entry, percpu_rwsem_wake_function); + bool wait; + + spin_lock_irq(&sem->waiters.lock); + /* + * Serialize against the wakeup in percpu_up_write(), if we fail + * the trylock, the wakeup must see us on the list. + */ + wait = !__percpu_rwsem_trylock(sem, reader); + if (wait) { + wq_entry.flags |= WQ_FLAG_EXCLUSIVE | reader * WQ_FLAG_CUSTOM; + __add_wait_queue_entry_tail(&sem->waiters, &wq_entry); + } + spin_unlock_irq(&sem->waiters.lock); + + while (wait) { + set_current_state(TASK_UNINTERRUPTIBLE); + if (!smp_load_acquire(&wq_entry.private)) + break; + schedule(); + } + __set_current_state(TASK_RUNNING); +} + +bool __sched __percpu_down_read(struct percpu_rw_semaphore *sem, bool try) +{ + if (__percpu_down_read_trylock(sem)) + return true; + + if (try) + return false; + + trace_contention_begin(sem, LCB_F_PERCPU | LCB_F_READ); + preempt_enable(); + percpu_rwsem_wait(sem, /* .reader = */ true); + preempt_disable(); + trace_contention_end(sem, 0); + + return true; +} +EXPORT_SYMBOL_GPL(__percpu_down_read); + +#define per_cpu_sum(var) \ +({ \ + typeof(var) __sum = 0; \ + int cpu; \ + compiletime_assert_atomic_type(__sum); \ + for_each_possible_cpu(cpu) \ + __sum += per_cpu(var, cpu); \ + __sum; \ +}) + +bool percpu_is_read_locked(struct percpu_rw_semaphore *sem) +{ + return per_cpu_sum(*sem->read_count) != 0 && !atomic_read(&sem->block); +} +EXPORT_SYMBOL_GPL(percpu_is_read_locked); + +/* + * Return true if the modular sum of the sem->read_count per-CPU variable is + * zero. If this sum is zero, then it is stable due to the fact that if any + * newly arriving readers increment a given counter, they will immediately + * decrement that same counter. + * + * Assumes sem->block is set. + */ +static bool readers_active_check(struct percpu_rw_semaphore *sem) +{ + if (per_cpu_sum(*sem->read_count) != 0) + return false; + + /* + * If we observed the decrement; ensure we see the entire critical + * section. + */ + + smp_mb(); /* C matches B */ + + return true; +} + +void __sched percpu_down_write(struct percpu_rw_semaphore *sem) +{ + might_sleep(); + rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); + trace_contention_begin(sem, LCB_F_PERCPU | LCB_F_WRITE); + + /* Notify readers to take the slow path. */ + rcu_sync_enter(&sem->rss); + + /* + * Try set sem->block; this provides writer-writer exclusion. + * Having sem->block set makes new readers block. + */ + if (!__percpu_down_write_trylock(sem)) + percpu_rwsem_wait(sem, /* .reader = */ false); + + /* smp_mb() implied by __percpu_down_write_trylock() on success -- D matches A */ + + /* + * If they don't see our store of sem->block, then we are guaranteed to + * see their sem->read_count increment, and therefore will wait for + * them. + */ + + /* Wait for all active readers to complete. */ + rcuwait_wait_event(&sem->writer, readers_active_check(sem), TASK_UNINTERRUPTIBLE); + trace_contention_end(sem, 0); +} +EXPORT_SYMBOL_GPL(percpu_down_write); + +void percpu_up_write(struct percpu_rw_semaphore *sem) +{ + rwsem_release(&sem->dep_map, _RET_IP_); + + /* + * Signal the writer is done, no fast path yet. + * + * One reason that we cannot just immediately flip to readers_fast is + * that new readers might fail to see the results of this writer's + * critical section. + * + * Therefore we force it through the slow path which guarantees an + * acquire and thereby guarantees the critical section's consistency. + */ + atomic_set_release(&sem->block, 0); + + /* + * Prod any pending reader/writer to make progress. + */ + __wake_up(&sem->waiters, TASK_NORMAL, 1, sem); + + /* + * Once this completes (at least one RCU-sched grace period hence) the + * reader fast path will be available again. Safe to use outside the + * exclusive write lock because its counting. + */ + rcu_sync_exit(&sem->rss); +} +EXPORT_SYMBOL_GPL(percpu_up_write); |