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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
81 lines
3.7 KiB
C
81 lines
3.7 KiB
C
/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
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│ vi: set noet ft=c ts=8 sw=8 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2016 Google Inc. │
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│ │
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│ Licensed under the Apache License, Version 2.0 (the "License"); │
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│ you may not use this file except in compliance with the License. │
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│ You may obtain a copy of the License at │
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│ │
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│ http://www.apache.org/licenses/LICENSE-2.0 │
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│ │
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│ Unless required by applicable law or agreed to in writing, software │
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│ distributed under the License is distributed on an "AS IS" BASIS, │
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│ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. │
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│ See the License for the specific language governing permissions and │
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│ limitations under the License. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "third_party/nsync/mu_semaphore.internal.h"
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#include "libc/calls/cp.internal.h"
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#include "libc/dce.h"
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#include "third_party/nsync/mu_semaphore.h"
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__static_yoink("nsync_notice");
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/* Initialize *s; the initial value is 0. */
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bool nsync_mu_semaphore_init (nsync_semaphore *s) {
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if (IsNetbsd ()) {
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return nsync_mu_semaphore_init_sem (s);
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} else {
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return nsync_mu_semaphore_init_futex (s);
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}
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}
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/* Destroy *s. */
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void nsync_mu_semaphore_destroy (nsync_semaphore *s) {
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if (IsNetbsd ()) {
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return nsync_mu_semaphore_destroy_sem (s);
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} else {
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return nsync_mu_semaphore_destroy_futex (s);
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}
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}
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/* Wait until the count of *s exceeds 0, and decrement it. If POSIX cancellations
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are currently disabled by the thread, then this function always succeeds. When
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they're enabled in MASKED mode, this function may return ECANCELED. Otherwise,
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cancellation will occur by unwinding cleanup handlers pushed to the stack. */
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errno_t nsync_mu_semaphore_p (nsync_semaphore *s) {
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errno_t err;
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BEGIN_CANCELATION_POINT;
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if (IsNetbsd ()) {
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err = nsync_mu_semaphore_p_sem (s);
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} else {
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err = nsync_mu_semaphore_p_futex (s);
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}
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END_CANCELATION_POINT;
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return err;
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}
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/* Like nsync_mu_semaphore_p() this waits for the count of *s to exceed 0,
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while additionally supporting a time parameter specifying at what point
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in the future ETIMEDOUT should be returned, if neither cancelation, or
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semaphore release happens. */
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errno_t nsync_mu_semaphore_p_with_deadline (nsync_semaphore *s, int clock, nsync_time abs_deadline) {
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errno_t err;
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BEGIN_CANCELATION_POINT;
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if (IsNetbsd ()) {
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err = nsync_mu_semaphore_p_with_deadline_sem (s, clock, abs_deadline);
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} else {
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err = nsync_mu_semaphore_p_with_deadline_futex (s, clock, abs_deadline);
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}
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END_CANCELATION_POINT;
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return err;
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}
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/* Ensure that the count of *s is at least 1. */
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void nsync_mu_semaphore_v (nsync_semaphore *s) {
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if (IsNetbsd ()) {
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return nsync_mu_semaphore_v_sem (s);
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} else {
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return nsync_mu_semaphore_v_futex (s);
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}
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}
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