platform_bionic/libc/bionic/pthread_setschedparam.cpp

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/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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 COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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
* COPYRIGHT OWNER OR CONTRIBUTORS 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.
*/
#include <errno.h>
#include <pthread.h>
#include <sched.h>
#include "private/ErrnoRestorer.h"
#include "pthread_internal.h"
int pthread_setschedparam(pthread_t t, int policy, const sched_param* param) {
ErrnoRestorer errno_restorer;
pid_t tid = __pthread_internal_gettid(t, "pthread_setschedparam");
Be more strict about using invalid `pthread_t`s. Another release, another attempt to remove the global thread list. But this time, let's admit that it's not going away. We can switch to using a read/write lock for the global thread list, and to aborting rather than quietly returning ESRCH if we're given an invalid pthread_t. This change affects pthread_detach, pthread_getcpuclockid, pthread_getschedparam/pthread_setschedparam, pthread_join, and pthread_kill: instead of returning ESRCH when passed an invalid pthread_t, if you're targeting O or above, they'll abort with the message "attempt to use invalid pthread_t". Note that this doesn't change behavior as much as you might think: the old lookup only held the global thread list lock for the duration of the lookup, so there was still a race between that and the dereference in the caller, given that callers actually need the tid to pass to some syscall or other, and sometimes update fields in the pthread_internal_t struct too. (This patch replaces such users with calls to pthread_gettid_np, which at least makes the TOCTOU window smaller.) We can't check thread->tid against 0 to see whether a pthread_t is still valid because a dead thread gets its thread struct unmapped along with its stack, so the dereference isn't safe. Taking the affected functions one by one: * pthread_getcpuclockid and pthread_getschedparam/pthread_setschedparam should be fine. Unsafe calls to those seem highly unlikely. * Unsafe pthread_detach callers probably want to switch to pthread_attr_setdetachstate instead, or using pthread_detach(pthread_self()) from the new thread's start routine rather than doing the detach in the parent. * pthread_join calls should be safe anyway, because a joinable thread won't actually exit and unmap until it's joined. If you're joining an unjoinable thread, the fix is to stop marking it detached. If you're joining an already-joined thread, you need to rethink your design. * Unsafe pthread_kill calls aren't portably fixable. (And are obviously inherently non-portable as-is.) The best alternative on Android is to use pthread_gettid_np at some point that you know the thread to be alive, and then call kill/tgkill directly. That's still not completely safe because if you're too late, the tid may have been reused, but then your code is inherently unsafe anyway. Bug: http://b/19636317 Test: ran tests Change-Id: I0372c4428e8a7f1c3af5c9334f5d9c25f2c73f21
2017-02-14 02:59:29 +01:00
if (tid == -1) return ESRCH;
Be more strict about using invalid `pthread_t`s. Another release, another attempt to remove the global thread list. But this time, let's admit that it's not going away. We can switch to using a read/write lock for the global thread list, and to aborting rather than quietly returning ESRCH if we're given an invalid pthread_t. This change affects pthread_detach, pthread_getcpuclockid, pthread_getschedparam/pthread_setschedparam, pthread_join, and pthread_kill: instead of returning ESRCH when passed an invalid pthread_t, if you're targeting O or above, they'll abort with the message "attempt to use invalid pthread_t". Note that this doesn't change behavior as much as you might think: the old lookup only held the global thread list lock for the duration of the lookup, so there was still a race between that and the dereference in the caller, given that callers actually need the tid to pass to some syscall or other, and sometimes update fields in the pthread_internal_t struct too. (This patch replaces such users with calls to pthread_gettid_np, which at least makes the TOCTOU window smaller.) We can't check thread->tid against 0 to see whether a pthread_t is still valid because a dead thread gets its thread struct unmapped along with its stack, so the dereference isn't safe. Taking the affected functions one by one: * pthread_getcpuclockid and pthread_getschedparam/pthread_setschedparam should be fine. Unsafe calls to those seem highly unlikely. * Unsafe pthread_detach callers probably want to switch to pthread_attr_setdetachstate instead, or using pthread_detach(pthread_self()) from the new thread's start routine rather than doing the detach in the parent. * pthread_join calls should be safe anyway, because a joinable thread won't actually exit and unmap until it's joined. If you're joining an unjoinable thread, the fix is to stop marking it detached. If you're joining an already-joined thread, you need to rethink your design. * Unsafe pthread_kill calls aren't portably fixable. (And are obviously inherently non-portable as-is.) The best alternative on Android is to use pthread_gettid_np at some point that you know the thread to be alive, and then call kill/tgkill directly. That's still not completely safe because if you're too late, the tid may have been reused, but then your code is inherently unsafe anyway. Bug: http://b/19636317 Test: ran tests Change-Id: I0372c4428e8a7f1c3af5c9334f5d9c25f2c73f21
2017-02-14 02:59:29 +01:00
return (sched_setscheduler(tid, policy, param) == -1) ? errno : 0;
}
int pthread_setschedprio(pthread_t t, int priority) {
ErrnoRestorer errno_restorer;
pid_t tid = __pthread_internal_gettid(t, "pthread_setschedprio");
if (tid == -1) return ESRCH;
sched_param param = { .sched_priority = priority };
return (sched_setparam(tid, &param) == -1) ? errno : 0;
}