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https://github.com/jart/cosmopolitan.git
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98c5847727
This change fixes a bug where nsync waiter objects would leak. It'd mean that long-running programs like runitd would run out of file descriptors on NetBSD where waiter objects have ksem file descriptors. On other OSes this bug is mostly harmless since the worst that can happen with a futex is to leak a little bit of ram. The bug was caused because tib_nsync was sneaking back in after the finalization code had cleared it. This change refactors the thread exiting code to handle nsync teardown appropriately and in making this change I found another issue, which is that user code which is buggy, and tries to exit without joining joinable threads which haven't been detached, would result in a deadlock. That doesn't sound so bad, except the main thread is a joinable thread. So this deadlock would be triggered in ways that put libc at fault. So we now auto-join threads and libc will log a warning to --strace when that happens for any thread
118 lines
4.4 KiB
C
118 lines
4.4 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/mem/leaks.h"
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#include "libc/cxxabi.h"
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#include "libc/intrin/cxaatexit.h"
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#include "libc/intrin/dll.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/intrin/weaken.h"
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#include "libc/macros.h"
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#include "libc/mem/mem.h"
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#include "libc/nt/typedef/imagetlscallback.h"
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#include "libc/runtime/runtime.h"
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#include "libc/thread/posixthread.internal.h"
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#include "libc/thread/thread.h"
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#include "libc/thread/tls.h"
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#define LEAK_CONTAINER(e) DLL_CONTAINER(struct Leak, elem, e)
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struct Leak {
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void *alloc;
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struct Dll elem;
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};
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static int leak_count;
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static struct Dll *leaks;
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static struct Dll *freaks;
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static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
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void __may_leak(void *alloc) {
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if (!alloc)
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return;
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_pthread_mutex_lock(&lock);
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if (dll_is_empty(freaks)) {
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int g = __gransize;
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struct Leak *p = _mapanon(g);
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int n = g / sizeof(struct Leak);
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for (int i = 0; i < n; ++i) {
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dll_init(&p[i].elem);
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dll_make_first(&freaks, &p[i].elem);
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}
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}
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struct Dll *e = dll_first(freaks);
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LEAK_CONTAINER(e)->alloc = alloc;
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dll_remove(&freaks, e);
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dll_make_first(&leaks, e);
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_pthread_mutex_unlock(&lock);
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}
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static void visitor(void *start, void *end, size_t used_bytes, void *arg) {
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if (!used_bytes)
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return;
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for (struct Dll *e = dll_first(leaks); e; e = dll_next(leaks, e))
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if (start == LEAK_CONTAINER(e)->alloc)
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return;
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kprintf("error: leaked %'zu byte allocation at %p\n", used_bytes, start);
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++leak_count;
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}
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/**
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* Tests for memory leaks.
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*/
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void CheckForMemoryLeaks(void) {
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// validate usage of this api
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if (_weaken(_pthread_decimate))
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_weaken(_pthread_decimate)(kPosixThreadZombie);
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if (!pthread_orphan_np())
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kprintf("warning: called CheckForMemoryLeaks() from non-orphaned thread\n");
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// call dynamic global destructors
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__cxa_thread_finalize();
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__cxa_finalize(0);
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// check for leaks
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malloc_inspect_all(visitor, 0);
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if (leak_count) {
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kprintf(" you forgot to call free %'d time%s\n", leak_count,
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leak_count == 1 ? "" : "s");
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_exit(73);
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}
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}
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static bool IsHoldingLocks(struct CosmoTib *tib) {
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for (int i = 0; i < ARRAYLEN(tib->tib_locks); ++i)
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if (tib->tib_locks[i])
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return true;
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return false;
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}
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/**
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* Aborts if any locks are held by calling thread.
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*/
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void AssertNoLocksAreHeld(void) {
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struct CosmoTib *tib = __get_tls();
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if (IsHoldingLocks(tib)) {
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kprintf("error: the following locks are held by this thread:\n");
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for (int i = 0; i < ARRAYLEN(tib->tib_locks); ++i)
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if (tib->tib_locks[i])
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kprintf("\t- %t\n", tib->tib_locks[i]);
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_Exit(74);
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}
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}
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