From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- include/linux/srcutiny.h | 93 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 include/linux/srcutiny.h (limited to 'include/linux/srcutiny.h') diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h new file mode 100644 index 000000000..5aa5e0faf --- /dev/null +++ b/include/linux/srcutiny.h @@ -0,0 +1,93 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Sleepable Read-Copy Update mechanism for mutual exclusion, + * tiny variant. + * + * Copyright (C) IBM Corporation, 2017 + * + * Author: Paul McKenney + */ + +#ifndef _LINUX_SRCU_TINY_H +#define _LINUX_SRCU_TINY_H + +#include + +struct srcu_struct { + short srcu_lock_nesting[2]; /* srcu_read_lock() nesting depth. */ + u8 srcu_gp_running; /* GP workqueue running? */ + u8 srcu_gp_waiting; /* GP waiting for readers? */ + unsigned long srcu_idx; /* Current reader array element in bit 0x2. */ + unsigned long srcu_idx_max; /* Furthest future srcu_idx request. */ + struct swait_queue_head srcu_wq; + /* Last srcu_read_unlock() wakes GP. */ + struct rcu_head *srcu_cb_head; /* Pending callbacks: Head. */ + struct rcu_head **srcu_cb_tail; /* Pending callbacks: Tail. */ + struct work_struct srcu_work; /* For driving grace periods. */ +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ +}; + +void srcu_drive_gp(struct work_struct *wp); + +#define __SRCU_STRUCT_INIT(name, __ignored) \ +{ \ + .srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq), \ + .srcu_cb_tail = &name.srcu_cb_head, \ + .srcu_work = __WORK_INITIALIZER(name.srcu_work, srcu_drive_gp), \ + __SRCU_DEP_MAP_INIT(name) \ +} + +/* + * This odd _STATIC_ arrangement is needed for API compatibility with + * Tree SRCU, which needs some per-CPU data. + */ +#define DEFINE_SRCU(name) \ + struct srcu_struct name = __SRCU_STRUCT_INIT(name, name) +#define DEFINE_STATIC_SRCU(name) \ + static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name) + +void synchronize_srcu(struct srcu_struct *ssp); + +/* + * Counts the new reader in the appropriate per-CPU element of the + * srcu_struct. Can be invoked from irq/bh handlers, but the matching + * __srcu_read_unlock() must be in the same handler instance. Returns an + * index that must be passed to the matching srcu_read_unlock(). + */ +static inline int __srcu_read_lock(struct srcu_struct *ssp) +{ + int idx; + + idx = ((READ_ONCE(ssp->srcu_idx) + 1) & 0x2) >> 1; + WRITE_ONCE(ssp->srcu_lock_nesting[idx], READ_ONCE(ssp->srcu_lock_nesting[idx]) + 1); + return idx; +} + +static inline void synchronize_srcu_expedited(struct srcu_struct *ssp) +{ + synchronize_srcu(ssp); +} + +static inline void srcu_barrier(struct srcu_struct *ssp) +{ + synchronize_srcu(ssp); +} + +/* Defined here to avoid size increase for non-torture kernels. */ +static inline void srcu_torture_stats_print(struct srcu_struct *ssp, + char *tt, char *tf) +{ + int idx; + + idx = ((data_race(READ_ONCE(ssp->srcu_idx)) + 1) & 0x2) >> 1; + pr_alert("%s%s Tiny SRCU per-CPU(idx=%d): (%hd,%hd) gp: %lu->%lu\n", + tt, tf, idx, + data_race(READ_ONCE(ssp->srcu_lock_nesting[!idx])), + data_race(READ_ONCE(ssp->srcu_lock_nesting[idx])), + data_race(READ_ONCE(ssp->srcu_idx)), + data_race(READ_ONCE(ssp->srcu_idx_max))); +} + +#endif -- cgit v1.2.3