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Further improve mmap() locking story

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The way to use double linked lists, is to remove all the things you want
to work on, insert them into a new list on the stack. Then once you have
all the work items, you release the lock, do your work, and then lock it
again, to add the shelled out items back to a global freelist.
This commit is contained in:
Justine Tunney 2024-06-29 17:12:25 -07:00
parent 98e684622b
commit 1bf2d8e308
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
8 changed files with 84 additions and 101 deletions
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1
ctl/BUILD.mk
View file

@ -18,6 +18,7 @@ CTL_A_CHECKS = \
CTL_A_DIRECTDEPS = \
LIBC_INTRIN \
LIBC_MEM \
LIBC_NEXGEN32E \
LIBC_STDIO \
LIBC_STR \
THIRD_PARTY_GDTOA \

1
libc/intrin/maps.h
View file

@ -39,7 +39,6 @@ struct AddrSize {
extern struct Maps __maps;
void *randaddr(void);
void __maps_init(void);
void __maps_lock(void);
void __maps_check(void);

91
libc/intrin/mmap.c
View file

@ -21,6 +21,7 @@
#include "libc/calls/blockcancel.internal.h"
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/state.internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
@ -187,10 +188,10 @@ int __munmap(char *addr, size_t size, bool untrack_only) {
!size || (uintptr_t)addr + size < size)
return einval();
// untrack and delete mapping
// untrack mappings
int rc = 0;
struct Dll *delete = 0;
__maps_lock();
StartOver:;
struct Map *map = __maps.maps;
struct Map **prev = &__maps.maps;
while (map) {
@ -202,30 +203,10 @@ StartOver:;
if (addr <= map_addr && addr + PGUP(size) >= map_addr + PGUP(map_size)) {
// remove mapping completely
dll_remove(&__maps.used, &map->elem);
dll_make_first(&delete, &map->elem);
*prev = next;
__maps.pages -= (map_size + pagesz - 1) / pagesz;
__maps.count -= 1;
if (untrack_only) {
__maps_free(map);
__maps_check();
} else {
__maps_unlock();
if (!IsWindows()) {
ASSERT(addr <= map_addr);
ASSERT(map_addr + PGUP(map_size) <= addr + PGUP(size));
if (sys_munmap(map_addr, map_size))
rc = -1;
} else {
if (!UnmapViewOfFile(map_addr))
rc = -1;
if (!CloseHandle(map->h))
rc = -1;
}
__maps_lock();
__maps_free(map);
__maps_check();
goto StartOver;
}
map = next;
continue;
} else if (IsWindows()) {
@ -240,35 +221,34 @@ StartOver:;
size_t right = map_size - left;
ASSERT(right > 0);
ASSERT(left > 0);
struct Map *leftmap;
if ((leftmap = __maps_alloc())) {
map->addr += left;
map->size = right;
if (!(map->flags & MAP_ANONYMOUS))
map->off += left;
__maps.pages -= (left + pagesz - 1) / pagesz;
__maps_check();
if (!untrack_only) {
__maps_unlock();
ASSERT(addr <= map_addr);
ASSERT(map_addr + PGUP(left) <= addr + PGUP(size));
if (sys_munmap(map_addr, left) == -1)
leftmap->addr = map_addr;
leftmap->size = left;
dll_make_first(&delete, &leftmap->elem);
} else {
rc = -1;
__maps_lock();
goto StartOver;
}
} else if (addr + PGUP(size) >= map_addr + PGUP(map_size)) {
// shave off righthand side of mapping
size_t left = addr - map_addr;
size_t right = map_addr + map_size - addr;
struct Map *rightmap;
if ((rightmap = __maps_alloc())) {
map->size = left;
__maps.pages -= (right + pagesz - 1) / pagesz;
__maps_check();
if (!untrack_only) {
__maps_unlock();
ASSERT(PGUP(right) <= PGUP(size));
if (sys_munmap(addr, right) == -1)
rightmap->addr = addr;
rightmap->size = right;
dll_make_first(&delete, &rightmap->elem);
} else {
rc = -1;
__maps_lock();
goto StartOver;
}
} else {
// punch hole in mapping
@ -277,6 +257,8 @@ StartOver:;
size_t right = map_size - middle - left;
struct Map *leftmap;
if ((leftmap = __maps_alloc())) {
struct Map *middlemap;
if ((middlemap = __maps_alloc())) {
leftmap->next = map;
leftmap->addr = map_addr;
leftmap->size = left;
@ -292,12 +274,11 @@ StartOver:;
__maps.pages -= (middle + pagesz - 1) / pagesz;
__maps.count += 1;
__maps_check();
if (!untrack_only) {
__maps_unlock();
if (sys_munmap(addr, size) == -1)
middlemap->addr = addr;
middlemap->size = size;
dll_make_first(&delete, &middlemap->elem);
} else {
rc = -1;
__maps_lock();
goto StartOver;
}
} else {
rc = -1;
@ -309,6 +290,34 @@ StartOver:;
}
__maps_unlock();
// delete mappings
for (struct Dll *e = dll_first(delete); e; e = dll_next(delete, e)) {
map = MAP_CONTAINER(e);
if (!untrack_only) {
if (!IsWindows()) {
if (sys_munmap(map->addr, map->size))
rc = -1;
} else {
if (!UnmapViewOfFile(map->addr))
rc = -1;
if (!CloseHandle(map->h))
rc = -1;
}
}
}
// free mappings
if (!dll_is_empty(delete)) {
__maps_lock();
struct Dll *e;
while ((e = dll_first(delete))) {
dll_remove(&delete, e);
__maps_free(MAP_CONTAINER(e));
}
__maps_check();
__maps_unlock();
}
return rc;
}

25
libc/intrin/randaddr.c
View file

@ -1,25 +0,0 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2024 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
void *randaddr(void) {
static unsigned long lcg = 1;
lcg *= 6364136223846793005;
lcg += 1442695040888963407;
return (void *)(lcg >> 48 << 28);
}

6
libc/intrin/reservefd.c
View file

@ -64,11 +64,9 @@ int __reservefd_unlocked(int start) {
int fd, f1, f2;
for (;;) {
f1 = atomic_load_explicit(&g_fds.f, memory_order_acquire);
for (fd = MAX(start, f1); fd < g_fds.n; ++fd) {
if (!g_fds.p[fd].kind) {
for (fd = MAX(start, f1); fd < g_fds.n; ++fd)
if (!g_fds.p[fd].kind)
break;
}
}
fd = __ensurefds_unlocked(fd);
bzero(g_fds.p + fd, sizeof(*g_fds.p));
if (_cmpxchg(&g_fds.p[fd].kind, kFdEmpty, kFdReserved)) {

2
libc/runtime/zipos-open.c
View file

@ -58,7 +58,7 @@ static struct ZiposHandle *__zipos_alloc(struct Zipos *zipos, size_t size) {
granularity = __granularity();
mapsize = sizeof(struct ZiposHandle) + size;
mapsize = (mapsize + granularity - 1) & -granularity;
if ((h = __mmap(randaddr(), mapsize, PROT_READ | PROT_WRITE,
if ((h = __mmap(0, mapsize, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)) != MAP_FAILED) {
h->size = size;
h->zipos = zipos;

1
test/ctl/BUILD.mk
View file

@ -17,6 +17,7 @@ TEST_CTL_DIRECTDEPS = \
LIBC_INTRIN \
LIBC_LOG \
LIBC_MEM \
LIBC_NEXGEN32E \
LIBC_STDIO \
LIBC_STDIO \
LIBC_THREAD \

4
tool/cosmocc/package.sh
View file

@ -90,10 +90,10 @@ fetch() {
OLD=$PWD
cd "$OUTDIR/"
if [ ! -x bin/x86_64-linux-cosmo-gcc ]; then
fetch https://github.com/ahgamut/superconfigure/releases/download/z0.0.44/aarch64-gcc.zip
fetch https://github.com/ahgamut/superconfigure/releases/download/z0.0.45/aarch64-gcc.zip
unzip aarch64-gcc.zip
rm -f aarch64-gcc.zip
fetch https://github.com/ahgamut/superconfigure/releases/download/z0.0.44/x86_64-gcc.zip
fetch https://github.com/ahgamut/superconfigure/releases/download/z0.0.45/x86_64-gcc.zip
unzip x86_64-gcc.zip
rm -f x86_64-gcc.zip
fi