From 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 21 Feb 2023 18:24:12 -0800 Subject: Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 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(). ... --- lib/lru_cache.c | 622 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 622 insertions(+) create mode 100644 lib/lru_cache.c (limited to 'lib/lru_cache.c') diff --git a/lib/lru_cache.c b/lib/lru_cache.c new file mode 100644 index 000000000..b3d918761 --- /dev/null +++ b/lib/lru_cache.c @@ -0,0 +1,622 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + lru_cache.c + + This file is part of DRBD by Philipp Reisner and Lars Ellenberg. + + Copyright (C) 2003-2008, LINBIT Information Technologies GmbH. + Copyright (C) 2003-2008, Philipp Reisner . + Copyright (C) 2003-2008, Lars Ellenberg . + + + */ + +#include +#include +#include +#include /* for memset */ +#include /* for seq_printf */ +#include + +MODULE_AUTHOR("Philipp Reisner , " + "Lars Ellenberg "); +MODULE_DESCRIPTION("lru_cache - Track sets of hot objects"); +MODULE_LICENSE("GPL"); + +/* this is developers aid only. + * it catches concurrent access (lack of locking on the users part) */ +#define PARANOIA_ENTRY() do { \ + BUG_ON(!lc); \ + BUG_ON(!lc->nr_elements); \ + BUG_ON(test_and_set_bit(__LC_PARANOIA, &lc->flags)); \ +} while (0) + +#define RETURN(x...) do { \ + clear_bit_unlock(__LC_PARANOIA, &lc->flags); \ + return x ; } while (0) + +/* BUG() if e is not one of the elements tracked by lc */ +#define PARANOIA_LC_ELEMENT(lc, e) do { \ + struct lru_cache *lc_ = (lc); \ + struct lc_element *e_ = (e); \ + unsigned i = e_->lc_index; \ + BUG_ON(i >= lc_->nr_elements); \ + BUG_ON(lc_->lc_element[i] != e_); } while (0) + + +/* We need to atomically + * - try to grab the lock (set LC_LOCKED) + * - only if there is no pending transaction + * (neither LC_DIRTY nor LC_STARVING is set) + * Because of PARANOIA_ENTRY() above abusing lc->flags as well, + * it is not sufficient to just say + * return 0 == cmpxchg(&lc->flags, 0, LC_LOCKED); + */ +int lc_try_lock(struct lru_cache *lc) +{ + unsigned long val; + do { + val = cmpxchg(&lc->flags, 0, LC_LOCKED); + } while (unlikely (val == LC_PARANOIA)); + /* Spin until no-one is inside a PARANOIA_ENTRY()/RETURN() section. */ + return 0 == val; +} + +/** + * lc_create - prepares to track objects in an active set + * @name: descriptive name only used in lc_seq_printf_stats and lc_seq_dump_details + * @cache: cache root pointer + * @max_pending_changes: maximum changes to accumulate until a transaction is required + * @e_count: number of elements allowed to be active simultaneously + * @e_size: size of the tracked objects + * @e_off: offset to the &struct lc_element member in a tracked object + * + * Returns a pointer to a newly initialized struct lru_cache on success, + * or NULL on (allocation) failure. + */ +struct lru_cache *lc_create(const char *name, struct kmem_cache *cache, + unsigned max_pending_changes, + unsigned e_count, size_t e_size, size_t e_off) +{ + struct hlist_head *slot = NULL; + struct lc_element **element = NULL; + struct lru_cache *lc; + struct lc_element *e; + unsigned cache_obj_size = kmem_cache_size(cache); + unsigned i; + + WARN_ON(cache_obj_size < e_size); + if (cache_obj_size < e_size) + return NULL; + + /* e_count too big; would probably fail the allocation below anyways. + * for typical use cases, e_count should be few thousand at most. */ + if (e_count > LC_MAX_ACTIVE) + return NULL; + + slot = kcalloc(e_count, sizeof(struct hlist_head), GFP_KERNEL); + if (!slot) + goto out_fail; + element = kcalloc(e_count, sizeof(struct lc_element *), GFP_KERNEL); + if (!element) + goto out_fail; + + lc = kzalloc(sizeof(*lc), GFP_KERNEL); + if (!lc) + goto out_fail; + + INIT_LIST_HEAD(&lc->in_use); + INIT_LIST_HEAD(&lc->lru); + INIT_LIST_HEAD(&lc->free); + INIT_LIST_HEAD(&lc->to_be_changed); + + lc->name = name; + lc->element_size = e_size; + lc->element_off = e_off; + lc->nr_elements = e_count; + lc->max_pending_changes = max_pending_changes; + lc->lc_cache = cache; + lc->lc_element = element; + lc->lc_slot = slot; + + /* preallocate all objects */ + for (i = 0; i < e_count; i++) { + void *p = kmem_cache_alloc(cache, GFP_KERNEL); + if (!p) + break; + memset(p, 0, lc->element_size); + e = p + e_off; + e->lc_index = i; + e->lc_number = LC_FREE; + e->lc_new_number = LC_FREE; + list_add(&e->list, &lc->free); + element[i] = e; + } + if (i == e_count) + return lc; + + /* else: could not allocate all elements, give up */ + while (i) { + void *p = element[--i]; + kmem_cache_free(cache, p - e_off); + } + kfree(lc); +out_fail: + kfree(element); + kfree(slot); + return NULL; +} + +static void lc_free_by_index(struct lru_cache *lc, unsigned i) +{ + void *p = lc->lc_element[i]; + WARN_ON(!p); + if (p) { + p -= lc->element_off; + kmem_cache_free(lc->lc_cache, p); + } +} + +/** + * lc_destroy - frees memory allocated by lc_create() + * @lc: the lru cache to destroy + */ +void lc_destroy(struct lru_cache *lc) +{ + unsigned i; + if (!lc) + return; + for (i = 0; i < lc->nr_elements; i++) + lc_free_by_index(lc, i); + kfree(lc->lc_element); + kfree(lc->lc_slot); + kfree(lc); +} + +/** + * lc_reset - does a full reset for @lc and the hash table slots. + * @lc: the lru cache to operate on + * + * It is roughly the equivalent of re-allocating a fresh lru_cache object, + * basically a short cut to lc_destroy(lc); lc = lc_create(...); + */ +void lc_reset(struct lru_cache *lc) +{ + unsigned i; + + INIT_LIST_HEAD(&lc->in_use); + INIT_LIST_HEAD(&lc->lru); + INIT_LIST_HEAD(&lc->free); + INIT_LIST_HEAD(&lc->to_be_changed); + lc->used = 0; + lc->hits = 0; + lc->misses = 0; + lc->starving = 0; + lc->locked = 0; + lc->changed = 0; + lc->pending_changes = 0; + lc->flags = 0; + memset(lc->lc_slot, 0, sizeof(struct hlist_head) * lc->nr_elements); + + for (i = 0; i < lc->nr_elements; i++) { + struct lc_element *e = lc->lc_element[i]; + void *p = e; + p -= lc->element_off; + memset(p, 0, lc->element_size); + /* re-init it */ + e->lc_index = i; + e->lc_number = LC_FREE; + e->lc_new_number = LC_FREE; + list_add(&e->list, &lc->free); + } +} + +/** + * lc_seq_printf_stats - print stats about @lc into @seq + * @seq: the seq_file to print into + * @lc: the lru cache to print statistics of + */ +void lc_seq_printf_stats(struct seq_file *seq, struct lru_cache *lc) +{ + /* NOTE: + * total calls to lc_get are + * (starving + hits + misses) + * misses include "locked" count (update from an other thread in + * progress) and "changed", when this in fact lead to an successful + * update of the cache. + */ + seq_printf(seq, "\t%s: used:%u/%u hits:%lu misses:%lu starving:%lu locked:%lu changed:%lu\n", + lc->name, lc->used, lc->nr_elements, + lc->hits, lc->misses, lc->starving, lc->locked, lc->changed); +} + +static struct hlist_head *lc_hash_slot(struct lru_cache *lc, unsigned int enr) +{ + return lc->lc_slot + (enr % lc->nr_elements); +} + + +static struct lc_element *__lc_find(struct lru_cache *lc, unsigned int enr, + bool include_changing) +{ + struct lc_element *e; + + BUG_ON(!lc); + BUG_ON(!lc->nr_elements); + hlist_for_each_entry(e, lc_hash_slot(lc, enr), colision) { + /* "about to be changed" elements, pending transaction commit, + * are hashed by their "new number". "Normal" elements have + * lc_number == lc_new_number. */ + if (e->lc_new_number != enr) + continue; + if (e->lc_new_number == e->lc_number || include_changing) + return e; + break; + } + return NULL; +} + +/** + * lc_find - find element by label, if present in the hash table + * @lc: The lru_cache object + * @enr: element number + * + * Returns the pointer to an element, if the element with the requested + * "label" or element number is present in the hash table, + * or NULL if not found. Does not change the refcnt. + * Ignores elements that are "about to be used", i.e. not yet in the active + * set, but still pending transaction commit. + */ +struct lc_element *lc_find(struct lru_cache *lc, unsigned int enr) +{ + return __lc_find(lc, enr, 0); +} + +/** + * lc_is_used - find element by label + * @lc: The lru_cache object + * @enr: element number + * + * Returns true, if the element with the requested "label" or element number is + * present in the hash table, and is used (refcnt > 0). + * Also finds elements that are not _currently_ used but only "about to be + * used", i.e. on the "to_be_changed" list, pending transaction commit. + */ +bool lc_is_used(struct lru_cache *lc, unsigned int enr) +{ + struct lc_element *e = __lc_find(lc, enr, 1); + return e && e->refcnt; +} + +/** + * lc_del - removes an element from the cache + * @lc: The lru_cache object + * @e: The element to remove + * + * @e must be unused (refcnt == 0). Moves @e from "lru" to "free" list, + * sets @e->enr to %LC_FREE. + */ +void lc_del(struct lru_cache *lc, struct lc_element *e) +{ + PARANOIA_ENTRY(); + PARANOIA_LC_ELEMENT(lc, e); + BUG_ON(e->refcnt); + + e->lc_number = e->lc_new_number = LC_FREE; + hlist_del_init(&e->colision); + list_move(&e->list, &lc->free); + RETURN(); +} + +static struct lc_element *lc_prepare_for_change(struct lru_cache *lc, unsigned new_number) +{ + struct list_head *n; + struct lc_element *e; + + if (!list_empty(&lc->free)) + n = lc->free.next; + else if (!list_empty(&lc->lru)) + n = lc->lru.prev; + else + return NULL; + + e = list_entry(n, struct lc_element, list); + PARANOIA_LC_ELEMENT(lc, e); + + e->lc_new_number = new_number; + if (!hlist_unhashed(&e->colision)) + __hlist_del(&e->colision); + hlist_add_head(&e->colision, lc_hash_slot(lc, new_number)); + list_move(&e->list, &lc->to_be_changed); + + return e; +} + +static int lc_unused_element_available(struct lru_cache *lc) +{ + if (!list_empty(&lc->free)) + return 1; /* something on the free list */ + if (!list_empty(&lc->lru)) + return 1; /* something to evict */ + + return 0; +} + +/* used as internal flags to __lc_get */ +enum { + LC_GET_MAY_CHANGE = 1, + LC_GET_MAY_USE_UNCOMMITTED = 2, +}; + +static struct lc_element *__lc_get(struct lru_cache *lc, unsigned int enr, unsigned int flags) +{ + struct lc_element *e; + + PARANOIA_ENTRY(); + if (test_bit(__LC_STARVING, &lc->flags)) { + ++lc->starving; + RETURN(NULL); + } + + e = __lc_find(lc, enr, 1); + /* if lc_new_number != lc_number, + * this enr is currently being pulled in already, + * and will be available once the pending transaction + * has been committed. */ + if (e) { + if (e->lc_new_number != e->lc_number) { + /* It has been found above, but on the "to_be_changed" + * list, not yet committed. Don't pull it in twice, + * wait for the transaction, then try again... + */ + if (!(flags & LC_GET_MAY_USE_UNCOMMITTED)) + RETURN(NULL); + /* ... unless the caller is aware of the implications, + * probably preparing a cumulative transaction. */ + ++e->refcnt; + ++lc->hits; + RETURN(e); + } + /* else: lc_new_number == lc_number; a real hit. */ + ++lc->hits; + if (e->refcnt++ == 0) + lc->used++; + list_move(&e->list, &lc->in_use); /* Not evictable... */ + RETURN(e); + } + /* e == NULL */ + + ++lc->misses; + if (!(flags & LC_GET_MAY_CHANGE)) + RETURN(NULL); + + /* To avoid races with lc_try_lock(), first, mark us dirty + * (using test_and_set_bit, as it implies memory barriers), ... */ + test_and_set_bit(__LC_DIRTY, &lc->flags); + + /* ... only then check if it is locked anyways. If lc_unlock clears + * the dirty bit again, that's not a problem, we will come here again. + */ + if (test_bit(__LC_LOCKED, &lc->flags)) { + ++lc->locked; + RETURN(NULL); + } + + /* In case there is nothing available and we can not kick out + * the LRU element, we have to wait ... + */ + if (!lc_unused_element_available(lc)) { + set_bit(__LC_STARVING, &lc->flags); + RETURN(NULL); + } + + /* It was not present in the active set. We are going to recycle an + * unused (or even "free") element, but we won't accumulate more than + * max_pending_changes changes. */ + if (lc->pending_changes >= lc->max_pending_changes) + RETURN(NULL); + + e = lc_prepare_for_change(lc, enr); + BUG_ON(!e); + + clear_bit(__LC_STARVING, &lc->flags); + BUG_ON(++e->refcnt != 1); + lc->used++; + lc->pending_changes++; + + RETURN(e); +} + +/** + * lc_get - get element by label, maybe change the active set + * @lc: the lru cache to operate on + * @enr: the label to look up + * + * Finds an element in the cache, increases its usage count, + * "touches" and returns it. + * + * In case the requested number is not present, it needs to be added to the + * cache. Therefore it is possible that an other element becomes evicted from + * the cache. In either case, the user is notified so he is able to e.g. keep + * a persistent log of the cache changes, and therefore the objects in use. + * + * Return values: + * NULL + * The cache was marked %LC_STARVING, + * or the requested label was not in the active set + * and a changing transaction is still pending (@lc was marked %LC_DIRTY). + * Or no unused or free element could be recycled (@lc will be marked as + * %LC_STARVING, blocking further lc_get() operations). + * + * pointer to the element with the REQUESTED element number. + * In this case, it can be used right away + * + * pointer to an UNUSED element with some different element number, + * where that different number may also be %LC_FREE. + * + * In this case, the cache is marked %LC_DIRTY, + * so lc_try_lock() will no longer succeed. + * The returned element pointer is moved to the "to_be_changed" list, + * and registered with the new element number on the hash collision chains, + * so it is possible to pick it up from lc_is_used(). + * Up to "max_pending_changes" (see lc_create()) can be accumulated. + * The user now should do whatever housekeeping is necessary, + * typically serialize on lc_try_lock_for_transaction(), then call + * lc_committed(lc) and lc_unlock(), to finish the change. + * + * NOTE: The user needs to check the lc_number on EACH use, so he recognizes + * any cache set change. + */ +struct lc_element *lc_get(struct lru_cache *lc, unsigned int enr) +{ + return __lc_get(lc, enr, LC_GET_MAY_CHANGE); +} + +/** + * lc_get_cumulative - like lc_get; also finds to-be-changed elements + * @lc: the lru cache to operate on + * @enr: the label to look up + * + * Unlike lc_get this also returns the element for @enr, if it is belonging to + * a pending transaction, so the return values are like for lc_get(), + * plus: + * + * pointer to an element already on the "to_be_changed" list. + * In this case, the cache was already marked %LC_DIRTY. + * + * Caller needs to make sure that the pending transaction is completed, + * before proceeding to actually use this element. + */ +struct lc_element *lc_get_cumulative(struct lru_cache *lc, unsigned int enr) +{ + return __lc_get(lc, enr, LC_GET_MAY_CHANGE|LC_GET_MAY_USE_UNCOMMITTED); +} + +/** + * lc_try_get - get element by label, if present; do not change the active set + * @lc: the lru cache to operate on + * @enr: the label to look up + * + * Finds an element in the cache, increases its usage count, + * "touches" and returns it. + * + * Return values: + * NULL + * The cache was marked %LC_STARVING, + * or the requested label was not in the active set + * + * pointer to the element with the REQUESTED element number. + * In this case, it can be used right away + */ +struct lc_element *lc_try_get(struct lru_cache *lc, unsigned int enr) +{ + return __lc_get(lc, enr, 0); +} + +/** + * lc_committed - tell @lc that pending changes have been recorded + * @lc: the lru cache to operate on + * + * User is expected to serialize on explicit lc_try_lock_for_transaction() + * before the transaction is started, and later needs to lc_unlock() explicitly + * as well. + */ +void lc_committed(struct lru_cache *lc) +{ + struct lc_element *e, *tmp; + + PARANOIA_ENTRY(); + list_for_each_entry_safe(e, tmp, &lc->to_be_changed, list) { + /* count number of changes, not number of transactions */ + ++lc->changed; + e->lc_number = e->lc_new_number; + list_move(&e->list, &lc->in_use); + } + lc->pending_changes = 0; + RETURN(); +} + + +/** + * lc_put - give up refcnt of @e + * @lc: the lru cache to operate on + * @e: the element to put + * + * If refcnt reaches zero, the element is moved to the lru list, + * and a %LC_STARVING (if set) is cleared. + * Returns the new (post-decrement) refcnt. + */ +unsigned int lc_put(struct lru_cache *lc, struct lc_element *e) +{ + PARANOIA_ENTRY(); + PARANOIA_LC_ELEMENT(lc, e); + BUG_ON(e->refcnt == 0); + BUG_ON(e->lc_number != e->lc_new_number); + if (--e->refcnt == 0) { + /* move it to the front of LRU. */ + list_move(&e->list, &lc->lru); + lc->used--; + clear_bit_unlock(__LC_STARVING, &lc->flags); + } + RETURN(e->refcnt); +} + +/** + * lc_element_by_index + * @lc: the lru cache to operate on + * @i: the index of the element to return + */ +struct lc_element *lc_element_by_index(struct lru_cache *lc, unsigned i) +{ + BUG_ON(i >= lc->nr_elements); + BUG_ON(lc->lc_element[i] == NULL); + BUG_ON(lc->lc_element[i]->lc_index != i); + return lc->lc_element[i]; +} + +/** + * lc_seq_dump_details - Dump a complete LRU cache to seq in textual form. + * @lc: the lru cache to operate on + * @seq: the &struct seq_file pointer to seq_printf into + * @utext: user supplied additional "heading" or other info + * @detail: function pointer the user may provide to dump further details + * of the object the lc_element is embedded in. May be NULL. + * Note: a leading space ' ' and trailing newline '\n' is implied. + */ +void lc_seq_dump_details(struct seq_file *seq, struct lru_cache *lc, char *utext, + void (*detail) (struct seq_file *, struct lc_element *)) +{ + unsigned int nr_elements = lc->nr_elements; + struct lc_element *e; + int i; + + seq_printf(seq, "\tnn: lc_number (new nr) refcnt %s\n ", utext); + for (i = 0; i < nr_elements; i++) { + e = lc_element_by_index(lc, i); + if (e->lc_number != e->lc_new_number) + seq_printf(seq, "\t%5d: %6d %8d %6d ", + i, e->lc_number, e->lc_new_number, e->refcnt); + else + seq_printf(seq, "\t%5d: %6d %-8s %6d ", + i, e->lc_number, "-\"-", e->refcnt); + if (detail) + detail(seq, e); + seq_putc(seq, '\n'); + } +} + +EXPORT_SYMBOL(lc_create); +EXPORT_SYMBOL(lc_reset); +EXPORT_SYMBOL(lc_destroy); +EXPORT_SYMBOL(lc_del); +EXPORT_SYMBOL(lc_try_get); +EXPORT_SYMBOL(lc_find); +EXPORT_SYMBOL(lc_get); +EXPORT_SYMBOL(lc_put); +EXPORT_SYMBOL(lc_committed); +EXPORT_SYMBOL(lc_element_by_index); +EXPORT_SYMBOL(lc_seq_printf_stats); +EXPORT_SYMBOL(lc_seq_dump_details); +EXPORT_SYMBOL(lc_try_lock); +EXPORT_SYMBOL(lc_is_used); +EXPORT_SYMBOL(lc_get_cumulative); -- cgit v1.2.3