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These are the first few patches in the Scope-based Resource Management series that introduce the infrastructure but not any conversions as of yet. Adding the infrastructure now allows multiple people to start using them. Of note is that Sparse will need some work since it doesn't yet understand this attribute and might have decl-after-stmt issues -- but I think that's being worked on. -----BEGIN PGP SIGNATURE----- iQJJBAABCgAzFiEEv3OU3/byMaA0LqWJdkfhpEvA5LoFAmSZehYVHHBldGVyekBp bmZyYWRlYWQub3JnAAoJEHZH4aRLwOS6uC0P/0pduumvCE+osm869VOroHeVqz6B B36oqJlD1uqIA8JWiNW8TbpUUqTvU0FyW1jU1YnUdol5Kb3XH7APQIayGj2HM+Mc kMyHc4/ICxBzRI7STiBtCEbHIwYAfuibCAfuq7QP4GDw4vHKvUC7BUUaUdbQSey0 IyUsvgPqLRL1KW3tb2z7Zfz6Oo/f0A/+viTiqOKNxSctXaD7TOEUpIZ/RhIgWbIV as65sgzLD/87HV9LbtTyOQCxjR5lpDlTaITapMfgwC9bQ8vQwjmaX3WETIlUmufl 8QG3wiPIDynmqjmpEeY+Cyjcu/Gbz/2XENPgHBd6g2yJSFLSyhSGcDBAZ/lFKlnB eIJqwIFUvpMbAskNxHooNz1zHzqHhOYcCSUITRk6PG8AS1HOD/aNij4sWHMzJSWU R3ZUOEf5k6FkER3eAKxEEsJ2HtIurOVfvFXwN1e0iCKvNiQ1QdP74LddcJqsrTY6 ihXsfVbtJarM9dakuWgk3fOj79cx3BQEm82002vvNzhRRUB5Fx7v47lyB5mAcYEl Al9gsLg4mKkVNiRh/tcelchKPp9WOKcXFEKiqom75VNwZH4oa+KSaa4GdDUQZzNs 73/Zj6gPzFBP1iLwqicvg5VJIzacKuH59WRRQr1IudTxYgWE67yz1OVicplD0WaR l0tF9LFAdBHUy8m/ =adZ8 -----END PGP SIGNATURE----- Merge tag 'core_guards_for_6.5_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue Pull scope-based resource management infrastructure from Peter Zijlstra: "These are the first few patches in the Scope-based Resource Management series that introduce the infrastructure but not any conversions as of yet. Adding the infrastructure now allows multiple people to start using them. Of note is that Sparse will need some work since it doesn't yet understand this attribute and might have decl-after-stmt issues" * tag 'core_guards_for_6.5_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue: kbuild: Drop -Wdeclaration-after-statement locking: Introduce __cleanup() based infrastructure apparmor: Free up __cleanup() name dmaengine: ioat: Free up __cleanup() name
351 lines
11 KiB
C
351 lines
11 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Sleepable Read-Copy Update mechanism for mutual exclusion
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*
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* Copyright (C) IBM Corporation, 2006
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* Copyright (C) Fujitsu, 2012
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*
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* Author: Paul McKenney <paulmck@linux.ibm.com>
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* Lai Jiangshan <laijs@cn.fujitsu.com>
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*
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* For detailed explanation of Read-Copy Update mechanism see -
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* Documentation/RCU/ *.txt
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*
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*/
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#ifndef _LINUX_SRCU_H
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#define _LINUX_SRCU_H
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#include <linux/mutex.h>
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#include <linux/rcupdate.h>
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#include <linux/workqueue.h>
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#include <linux/rcu_segcblist.h>
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struct srcu_struct;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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int __init_srcu_struct(struct srcu_struct *ssp, const char *name,
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struct lock_class_key *key);
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#define init_srcu_struct(ssp) \
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({ \
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static struct lock_class_key __srcu_key; \
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\
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__init_srcu_struct((ssp), #ssp, &__srcu_key); \
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})
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#define __SRCU_DEP_MAP_INIT(srcu_name) .dep_map = { .name = #srcu_name },
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#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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int init_srcu_struct(struct srcu_struct *ssp);
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#define __SRCU_DEP_MAP_INIT(srcu_name)
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#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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#ifdef CONFIG_TINY_SRCU
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#include <linux/srcutiny.h>
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#elif defined(CONFIG_TREE_SRCU)
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#include <linux/srcutree.h>
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#else
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#error "Unknown SRCU implementation specified to kernel configuration"
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#endif
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void call_srcu(struct srcu_struct *ssp, struct rcu_head *head,
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void (*func)(struct rcu_head *head));
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void cleanup_srcu_struct(struct srcu_struct *ssp);
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int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp);
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void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases(ssp);
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void synchronize_srcu(struct srcu_struct *ssp);
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unsigned long get_state_synchronize_srcu(struct srcu_struct *ssp);
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unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp);
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bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie);
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#ifdef CONFIG_NEED_SRCU_NMI_SAFE
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int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp);
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void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) __releases(ssp);
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#else
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static inline int __srcu_read_lock_nmisafe(struct srcu_struct *ssp)
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{
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return __srcu_read_lock(ssp);
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}
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static inline void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx)
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{
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__srcu_read_unlock(ssp, idx);
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}
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#endif /* CONFIG_NEED_SRCU_NMI_SAFE */
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void srcu_init(void);
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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/**
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* srcu_read_lock_held - might we be in SRCU read-side critical section?
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* @ssp: The srcu_struct structure to check
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*
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* If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU
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* read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC,
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* this assumes we are in an SRCU read-side critical section unless it can
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* prove otherwise.
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*
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* Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
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* and while lockdep is disabled.
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*
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* Note that SRCU is based on its own statemachine and it doesn't
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* relies on normal RCU, it can be called from the CPU which
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* is in the idle loop from an RCU point of view or offline.
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*/
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static inline int srcu_read_lock_held(const struct srcu_struct *ssp)
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{
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if (!debug_lockdep_rcu_enabled())
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return 1;
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return lock_is_held(&ssp->dep_map);
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}
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/*
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* Annotations provide deadlock detection for SRCU.
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*
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* Similar to other lockdep annotations, except there is an additional
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* srcu_lock_sync(), which is basically an empty *write*-side critical section,
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* see lock_sync() for more information.
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*/
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/* Annotates a srcu_read_lock() */
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static inline void srcu_lock_acquire(struct lockdep_map *map)
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{
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lock_map_acquire_read(map);
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}
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/* Annotates a srcu_read_lock() */
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static inline void srcu_lock_release(struct lockdep_map *map)
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{
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lock_map_release(map);
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}
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/* Annotates a synchronize_srcu() */
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static inline void srcu_lock_sync(struct lockdep_map *map)
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{
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lock_map_sync(map);
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}
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#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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static inline int srcu_read_lock_held(const struct srcu_struct *ssp)
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{
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return 1;
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}
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#define srcu_lock_acquire(m) do { } while (0)
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#define srcu_lock_release(m) do { } while (0)
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#define srcu_lock_sync(m) do { } while (0)
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#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
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#define SRCU_NMI_UNKNOWN 0x0
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#define SRCU_NMI_UNSAFE 0x1
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#define SRCU_NMI_SAFE 0x2
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#if defined(CONFIG_PROVE_RCU) && defined(CONFIG_TREE_SRCU)
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void srcu_check_nmi_safety(struct srcu_struct *ssp, bool nmi_safe);
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#else
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static inline void srcu_check_nmi_safety(struct srcu_struct *ssp,
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bool nmi_safe) { }
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#endif
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/**
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* srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing
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* @p: the pointer to fetch and protect for later dereferencing
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* @ssp: pointer to the srcu_struct, which is used to check that we
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* really are in an SRCU read-side critical section.
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* @c: condition to check for update-side use
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*
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* If PROVE_RCU is enabled, invoking this outside of an RCU read-side
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* critical section will result in an RCU-lockdep splat, unless @c evaluates
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* to 1. The @c argument will normally be a logical expression containing
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* lockdep_is_held() calls.
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*/
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#define srcu_dereference_check(p, ssp, c) \
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__rcu_dereference_check((p), __UNIQUE_ID(rcu), \
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(c) || srcu_read_lock_held(ssp), __rcu)
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/**
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* srcu_dereference - fetch SRCU-protected pointer for later dereferencing
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* @p: the pointer to fetch and protect for later dereferencing
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* @ssp: pointer to the srcu_struct, which is used to check that we
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* really are in an SRCU read-side critical section.
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*
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* Makes rcu_dereference_check() do the dirty work. If PROVE_RCU
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* is enabled, invoking this outside of an RCU read-side critical
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* section will result in an RCU-lockdep splat.
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*/
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#define srcu_dereference(p, ssp) srcu_dereference_check((p), (ssp), 0)
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/**
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* srcu_dereference_notrace - no tracing and no lockdep calls from here
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* @p: the pointer to fetch and protect for later dereferencing
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* @ssp: pointer to the srcu_struct, which is used to check that we
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* really are in an SRCU read-side critical section.
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*/
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#define srcu_dereference_notrace(p, ssp) srcu_dereference_check((p), (ssp), 1)
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/**
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* srcu_read_lock - register a new reader for an SRCU-protected structure.
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* @ssp: srcu_struct in which to register the new reader.
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*
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* Enter an SRCU read-side critical section. Note that SRCU read-side
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* critical sections may be nested. However, it is illegal to
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* call anything that waits on an SRCU grace period for the same
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* srcu_struct, whether directly or indirectly. Please note that
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* one way to indirectly wait on an SRCU grace period is to acquire
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* a mutex that is held elsewhere while calling synchronize_srcu() or
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* synchronize_srcu_expedited().
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*
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* Note that srcu_read_lock() and the matching srcu_read_unlock() must
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* occur in the same context, for example, it is illegal to invoke
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* srcu_read_unlock() in an irq handler if the matching srcu_read_lock()
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* was invoked in process context.
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*/
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static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp)
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{
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int retval;
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srcu_check_nmi_safety(ssp, false);
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retval = __srcu_read_lock(ssp);
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srcu_lock_acquire(&ssp->dep_map);
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return retval;
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}
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/**
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* srcu_read_lock_nmisafe - register a new reader for an SRCU-protected structure.
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* @ssp: srcu_struct in which to register the new reader.
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*
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* Enter an SRCU read-side critical section, but in an NMI-safe manner.
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* See srcu_read_lock() for more information.
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*/
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static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp)
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{
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int retval;
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srcu_check_nmi_safety(ssp, true);
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retval = __srcu_read_lock_nmisafe(ssp);
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rcu_lock_acquire(&ssp->dep_map);
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return retval;
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}
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/* Used by tracing, cannot be traced and cannot invoke lockdep. */
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static inline notrace int
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srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp)
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{
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int retval;
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srcu_check_nmi_safety(ssp, false);
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retval = __srcu_read_lock(ssp);
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return retval;
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}
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/**
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* srcu_down_read - register a new reader for an SRCU-protected structure.
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* @ssp: srcu_struct in which to register the new reader.
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*
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* Enter a semaphore-like SRCU read-side critical section. Note that
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* SRCU read-side critical sections may be nested. However, it is
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* illegal to call anything that waits on an SRCU grace period for the
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* same srcu_struct, whether directly or indirectly. Please note that
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* one way to indirectly wait on an SRCU grace period is to acquire
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* a mutex that is held elsewhere while calling synchronize_srcu() or
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* synchronize_srcu_expedited(). But if you want lockdep to help you
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* keep this stuff straight, you should instead use srcu_read_lock().
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*
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* The semaphore-like nature of srcu_down_read() means that the matching
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* srcu_up_read() can be invoked from some other context, for example,
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* from some other task or from an irq handler. However, neither
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* srcu_down_read() nor srcu_up_read() may be invoked from an NMI handler.
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*
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* Calls to srcu_down_read() may be nested, similar to the manner in
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* which calls to down_read() may be nested.
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*/
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static inline int srcu_down_read(struct srcu_struct *ssp) __acquires(ssp)
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{
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WARN_ON_ONCE(in_nmi());
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srcu_check_nmi_safety(ssp, false);
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return __srcu_read_lock(ssp);
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}
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/**
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* srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
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* @ssp: srcu_struct in which to unregister the old reader.
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* @idx: return value from corresponding srcu_read_lock().
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*
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* Exit an SRCU read-side critical section.
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*/
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static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx)
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__releases(ssp)
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{
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WARN_ON_ONCE(idx & ~0x1);
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srcu_check_nmi_safety(ssp, false);
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srcu_lock_release(&ssp->dep_map);
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__srcu_read_unlock(ssp, idx);
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}
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/**
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* srcu_read_unlock_nmisafe - unregister a old reader from an SRCU-protected structure.
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* @ssp: srcu_struct in which to unregister the old reader.
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* @idx: return value from corresponding srcu_read_lock().
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*
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* Exit an SRCU read-side critical section, but in an NMI-safe manner.
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*/
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static inline void srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx)
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__releases(ssp)
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{
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WARN_ON_ONCE(idx & ~0x1);
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srcu_check_nmi_safety(ssp, true);
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rcu_lock_release(&ssp->dep_map);
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__srcu_read_unlock_nmisafe(ssp, idx);
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}
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/* Used by tracing, cannot be traced and cannot call lockdep. */
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static inline notrace void
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srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp)
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{
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srcu_check_nmi_safety(ssp, false);
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__srcu_read_unlock(ssp, idx);
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}
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/**
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* srcu_up_read - unregister a old reader from an SRCU-protected structure.
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* @ssp: srcu_struct in which to unregister the old reader.
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* @idx: return value from corresponding srcu_read_lock().
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*
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* Exit an SRCU read-side critical section, but not necessarily from
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* the same context as the maching srcu_down_read().
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*/
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static inline void srcu_up_read(struct srcu_struct *ssp, int idx)
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__releases(ssp)
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{
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WARN_ON_ONCE(idx & ~0x1);
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WARN_ON_ONCE(in_nmi());
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srcu_check_nmi_safety(ssp, false);
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__srcu_read_unlock(ssp, idx);
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}
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/**
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* smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock
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*
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* Converts the preceding srcu_read_unlock into a two-way memory barrier.
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*
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* Call this after srcu_read_unlock, to guarantee that all memory operations
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* that occur after smp_mb__after_srcu_read_unlock will appear to happen after
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* the preceding srcu_read_unlock.
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*/
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static inline void smp_mb__after_srcu_read_unlock(void)
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{
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/* __srcu_read_unlock has smp_mb() internally so nothing to do here. */
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}
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DEFINE_LOCK_GUARD_1(srcu, struct srcu_struct,
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_T->idx = srcu_read_lock(_T->lock),
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srcu_read_unlock(_T->lock, _T->idx),
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int idx)
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#endif
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