X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=src%2Frculfhash-mm-mmap.c;h=4bce972094881bf3d8dc031be87241cd933b18c4;hb=HEAD;hp=3cc3fa01c9d5ed5c16888ae8f02fb85ae65cf1de;hpb=6893800a4d1cc14dff0395ddcd660a5138db183d;p=userspace-rcu.git diff --git a/src/rculfhash-mm-mmap.c b/src/rculfhash-mm-mmap.c index 3cc3fa0..2b4bc42 100644 --- a/src/rculfhash-mm-mmap.c +++ b/src/rculfhash-mm-mmap.c @@ -1,75 +1,116 @@ +// SPDX-FileCopyrightText: 2011 Lai Jiangshan +// +// SPDX-License-Identifier: LGPL-2.1-or-later + /* - * rculfhash-mm-mmap.c - * * mmap/reservation based memory management for Lock-Free RCU Hash Table - * - * Copyright 2011 - Lai Jiangshan - * - * This library is free software; you can redistribute it and/or - * modify it under the terms of the GNU Lesser General Public - * License as published by the Free Software Foundation; either - * version 2.1 of the License, or (at your option) any later version. - * - * This library is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * Lesser General Public License for more details. - * - * You should have received a copy of the GNU Lesser General Public - * License along with this library; if not, write to the Free Software - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include +#include +#include +#include #include +#include #include "rculfhash-internal.h" #ifndef MAP_ANONYMOUS #define MAP_ANONYMOUS MAP_ANON #endif -/* reserve inaccessible memory space without allocation any memory */ -static void *memory_map(size_t length) +/* + * The allocation scheme used by the mmap based RCU hash table is to make a + * large unaccessible mapping to reserve memory without allocating it. + * Then smaller chunks are allocated by overlapping read/write mappings which + * do allocate memory. Deallocation is done by an overlapping unaccessible + * mapping. + * + * This scheme was tested on Linux, macOS and Solaris. However, on Cygwin the + * mmap wrapper is based on the Windows NtMapViewOfSection API which doesn't + * support overlapping mappings. + * + * An alternative to the overlapping mappings is to use mprotect to change the + * protection on chunks of the large mapping, read/write to allocate and none + * to deallocate. This works perfecty on Cygwin and Solaris but on Linux a + * call to madvise is also required to deallocate and it just doesn't work on + * macOS. + * + * For this reason, we keep to original scheme on all platforms except Cygwin. + */ + + +/* Reserve inaccessible memory space without allocating it */ +static +void *memory_map(size_t length) { - void *ret = mmap(NULL, length, PROT_NONE, - MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + void *ret; - assert(ret != MAP_FAILED); + ret = mmap(NULL, length, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (ret == MAP_FAILED) { + perror("mmap"); + abort(); + } return ret; } -static void memory_unmap(void *ptr, size_t length) +static +void memory_unmap(void *ptr, size_t length) { - int ret __attribute__((unused)); - - ret = munmap(ptr, length); + if (munmap(ptr, length)) { + perror("munmap"); + abort(); + } +} - assert(ret == 0); +#ifdef __CYGWIN__ +/* Set protection to read/write to allocate a memory chunk */ +static +void memory_populate(void *ptr, size_t length) +{ + if (mprotect(ptr, length, PROT_READ | PROT_WRITE)) { + perror("mprotect"); + abort(); + } } -static void memory_populate(void *ptr, size_t length) +/* Set protection to none to deallocate a memory chunk */ +static +void memory_discard(void *ptr, size_t length) { - void *ret __attribute__((unused)); + if (mprotect(ptr, length, PROT_NONE)) { + perror("mprotect"); + abort(); + } +} - ret = mmap(ptr, length, PROT_READ | PROT_WRITE, - MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); +#else /* __CYGWIN__ */ - assert(ret == ptr); +static +void memory_populate(void *ptr, size_t length) +{ + if (mmap(ptr, length, PROT_READ | PROT_WRITE, + MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, + -1, 0) != ptr) { + perror("mmap"); + abort(); + } } /* * Discard garbage memory and avoid system save it when try to swap it out. * Make it still reserved, inaccessible. */ -static void memory_discard(void *ptr, size_t length) +static +void memory_discard(void *ptr, size_t length) { - void *ret __attribute__((unused)); - - ret = mmap(ptr, length, PROT_NONE, - MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); - - assert(ret == ptr); + if (mmap(ptr, length, PROT_NONE, + MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, + -1, 0) != ptr) { + perror("mmap"); + abort(); + } } +#endif /* __CYGWIN__ */ static void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order) @@ -77,9 +118,9 @@ void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order) if (order == 0) { if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) { /* small table */ - ht->tbl_mmap = calloc(ht->max_nr_buckets, - sizeof(*ht->tbl_mmap)); - assert(ht->tbl_mmap); + ht->tbl_mmap = ht->alloc->calloc(ht->alloc->state, + ht->max_nr_buckets, sizeof(*ht->tbl_mmap)); + urcu_posix_assert(ht->tbl_mmap); return; } /* large table */ @@ -91,7 +132,7 @@ void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order) /* large table */ unsigned long len = 1UL << (order - 1); - assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets); + urcu_posix_assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets); memory_populate(ht->tbl_mmap + len, len * sizeof(*ht->tbl_mmap)); } @@ -109,7 +150,7 @@ void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order) if (order == 0) { if (ht->min_nr_alloc_buckets == ht->max_nr_buckets) { /* small table */ - poison_free(ht->tbl_mmap); + poison_free(ht->alloc, ht->tbl_mmap); return; } /* large table */ @@ -119,7 +160,7 @@ void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order) /* large table */ unsigned long len = 1UL << (order - 1); - assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets); + urcu_posix_assert(ht->min_nr_alloc_buckets < ht->max_nr_buckets); memory_discard(ht->tbl_mmap + len, len * sizeof(*ht->tbl_mmap)); } /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */ @@ -133,7 +174,7 @@ struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index) static struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets, - unsigned long max_nr_buckets) + unsigned long max_nr_buckets, const struct cds_lfht_alloc *alloc) { unsigned long page_bucket_size; @@ -148,7 +189,7 @@ struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets, } return __default_alloc_cds_lfht( - &cds_lfht_mm_mmap, sizeof(struct cds_lfht), + &cds_lfht_mm_mmap, alloc, sizeof(struct cds_lfht), min_nr_alloc_buckets, max_nr_buckets); }