Changeset View
Changeset View
Standalone View
Standalone View
sys/sys/smr_types.h
- This file was added.
/*- | |||||
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD | |||||
* | |||||
* Copyright (c) 2019, 2020 Jeffrey Roberson <jeff@FreeBSD.org> | |||||
* | |||||
* Redistribution and use in source and binary forms, with or without | |||||
* modification, are permitted provided that the following conditions | |||||
* are met: | |||||
* 1. Redistributions of source code must retain the above copyright | |||||
* notice unmodified, this list of conditions, and the following | |||||
* disclaimer. | |||||
* 2. Redistributions in binary form must reproduce the above copyright | |||||
* notice, this list of conditions and the following disclaimer in the | |||||
* documentation and/or other materials provided with the distribution. | |||||
* | |||||
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |||||
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |||||
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |||||
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |||||
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |||||
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |||||
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |||||
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |||||
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |||||
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |||||
* | |||||
* $FreeBSD$ | |||||
*/ | |||||
#ifndef _SYS_SMR_TYPES_H_ | |||||
#define _SYS_SMR_TYPES_H_ | |||||
#include <sys/_smr.h> | |||||
/* | |||||
* SMR Accessors are meant to provide safe access to SMR protected | |||||
* pointers and prevent misuse and accidental access. | |||||
* | |||||
* Accessors are grouped by type: | |||||
* entered - Use while in a read section (between smr_enter/smr_exit()) | |||||
* serialized - Use while holding a lock that serializes writers. Updates | |||||
* are synchronized with readers via included barriers. | |||||
* unserialized - Use after the memory is out of scope and not visible to | |||||
* readers. | |||||
* | |||||
* All acceses include a parameter for an assert to verify the required | |||||
* synchronization. For example, a writer might use: | |||||
* | |||||
* smr_serialized_store(pointer, value, mtx_owned(&writelock)); | |||||
* | |||||
* These are only enabled in INVARIANTS kernels. | |||||
*/ | |||||
/* Type restricting pointer access to force smr accessors. */ | |||||
#define SMR_POINTER(type) \ | |||||
struct { \ | |||||
type __ptr; /* Do not access directly */ \ | |||||
} | |||||
/* | |||||
* Read from an SMR protected pointer while in a read section. | |||||
*/ | |||||
#define smr_entered_load(p, smr) ({ \ | |||||
SMR_ASSERT(SMR_ENTERED((smr)), "smr_entered_load"); \ | |||||
(__typeof((p)->__ptr))atomic_load_acq_ptr((uintptr_t *)&(p)->__ptr); \ | |||||
}) | |||||
/* | |||||
* Read from an SMR protected pointer while serialized by an | |||||
* external mechanism. 'ex' should contain an assert that the | |||||
* external mechanism is held. i.e. mtx_owned() | |||||
*/ | |||||
#define smr_serialized_load(p, ex) ({ \ | |||||
SMR_ASSERT(ex, "smr_serialized_load"); \ | |||||
(__typeof((p)->__ptr))atomic_load_ptr(&(p)->__ptr); \ | |||||
}) | |||||
/* | |||||
* Store 'v' to an SMR protected pointer while serialized by an | |||||
* external mechanism. 'ex' should contain an assert that the | |||||
* external mechanism is held. i.e. mtx_owned() | |||||
* | |||||
* Writers that are serialized with mutual exclusion or on a single | |||||
* thread should use smr_serialized_store() rather than swap. | |||||
*/ | |||||
#define smr_serialized_store(p, v, ex) do { \ | |||||
SMR_ASSERT(ex, "smr_serialized_store"); \ | |||||
__typeof((p)->__ptr) _v = (v); \ | |||||
atomic_store_rel_ptr((uintptr_t *)&(p)->__ptr, (uintptr_t)_v); \ | |||||
} while (0) | |||||
/* | |||||
* swap 'v' with an SMR protected pointer and return the old value | |||||
* while serialized by an external mechanism. 'ex' should contain | |||||
* an assert that the external mechanism is provided. i.e. mtx_owned() | |||||
* | |||||
* Swap permits multiple writers to update a pointer concurrently. | |||||
*/ | |||||
#define smr_serialized_swap(p, v, ex) ({ \ | |||||
SMR_ASSERT(ex, "smr_serialized_swap"); \ | |||||
__typeof((p)->__ptr) _v = (v); \ | |||||
/* Release barrier guarantees contents are visible to reader */ \ | |||||
atomic_thread_fence_rel(); \ | |||||
(__typeof((p)->__ptr))atomic_swap_ptr( \ | |||||
(uintptr_t *)&(p)->__ptr, (uintptr_t)_v); \ | |||||
}) | |||||
/* | |||||
* Read from an SMR protected pointer when no serialization is required | |||||
* such as in the destructor callback or when the caller guarantees other | |||||
* synchronization. | |||||
*/ | |||||
#define smr_unserialized_load(p, ex) ({ \ | |||||
SMR_ASSERT(ex, "smr_unserialized_load"); \ | |||||
(__typeof((p)->__ptr))atomic_load_ptr(&(p)->__ptr); \ | |||||
}) | |||||
/* | |||||
* Store to an SMR protected pointer when no serialiation is required | |||||
* such as in the destructor callback or when the caller guarantees other | |||||
* synchronization. | |||||
*/ | |||||
#define smr_unserialized_store(p, v, ex) do { \ | |||||
SMR_ASSERT(ex, "smr_unserialized_store"); \ | |||||
__typeof((p)->__ptr) _v = (v); \ | |||||
atomic_store_ptr((uintptr_t *)&(p)->__ptr, (uintptr_t)_v); \ | |||||
} while (0) | |||||
#endif /* _SYS_SMR_TYPES_H_ */ |