mirror of git://sourceware.org/git/glibc.git
111 lines
4.2 KiB
C
111 lines
4.2 KiB
C
/* Copyright (C) 2002-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <setjmp.h>
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#include <stdlib.h>
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#include "pthreadP.h"
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/* Called by the INTERNAL_SYSCALL_CANCEL macro, check for cancellation and
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returns the syscall value or its negative error code. */
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long int
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__internal_syscall_cancel (__syscall_arg_t a1, __syscall_arg_t a2,
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__syscall_arg_t a3, __syscall_arg_t a4,
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__syscall_arg_t a5, __syscall_arg_t a6,
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__SYSCALL_CANCEL7_ARG_DEF
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__syscall_arg_t nr)
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{
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long int result;
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struct pthread *pd = THREAD_SELF;
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/* If cancellation is not enabled, call the syscall directly and also
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for thread terminatation to avoid call __syscall_do_cancel while
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executing cleanup handlers. */
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int ch = atomic_load_relaxed (&pd->cancelhandling);
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if (SINGLE_THREAD_P || !cancel_enabled (ch) || cancel_exiting (ch))
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{
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result = INTERNAL_SYSCALL_NCS_CALL (nr, a1, a2, a3, a4, a5, a6
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__SYSCALL_CANCEL7_ARCH_ARG7);
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if (INTERNAL_SYSCALL_ERROR_P (result))
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return -INTERNAL_SYSCALL_ERRNO (result);
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return result;
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}
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/* Call the arch-specific entry points that contains the globals markers
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to be checked by SIGCANCEL handler. */
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result = __syscall_cancel_arch (&pd->cancelhandling, nr, a1, a2, a3, a4, a5,
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a6 __SYSCALL_CANCEL7_ARCH_ARG7);
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/* If the cancellable syscall was interrupted by SIGCANCEL and it has no
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side-effect, cancel the thread if cancellation is enabled. */
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ch = atomic_load_relaxed (&pd->cancelhandling);
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/* The behaviour here assumes that EINTR is returned only if there are no
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visible side effects. POSIX Issue 7 has not yet provided any stronger
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language for close, and in theory the close syscall could return EINTR
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and leave the file descriptor open (conforming and leaks). It expects
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that no such kernel is used with glibc. */
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if (result == -EINTR && cancel_enabled_and_canceled (ch))
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__syscall_do_cancel ();
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return result;
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}
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/* Called by the SYSCALL_CANCEL macro, check for cancellation and return the
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syscall expected success value (usually 0) or, in case of failure, -1 and
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sets errno to syscall return value. */
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long int
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__syscall_cancel (__syscall_arg_t a1, __syscall_arg_t a2,
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__syscall_arg_t a3, __syscall_arg_t a4,
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__syscall_arg_t a5, __syscall_arg_t a6,
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__SYSCALL_CANCEL7_ARG_DEF __syscall_arg_t nr)
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{
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int r = __internal_syscall_cancel (a1, a2, a3, a4, a5, a6,
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__SYSCALL_CANCEL7_ARG nr);
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return __glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (r))
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? SYSCALL_ERROR_LABEL (INTERNAL_SYSCALL_ERRNO (r))
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: r;
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}
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/* Called by __syscall_cancel_arch or function above start the thread
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cancellation. */
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_Noreturn void
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__syscall_do_cancel (void)
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{
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struct pthread *self = THREAD_SELF;
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/* Disable thread cancellation to avoid cancellable entrypoints calling
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__syscall_do_cancel recursively. We atomic load relaxed to check the
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state of cancelhandling, there is no particular ordering requirement
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between the syscall call and the other thread setting our cancelhandling
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with a atomic store acquire.
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POSIX Issue 7 notes that the cancellation occurs asynchronously on the
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target thread, that implies there is no ordering requirements. It does
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not need a MO release store here. */
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int oldval = atomic_load_relaxed (&self->cancelhandling);
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while (1)
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{
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int newval = oldval | CANCELSTATE_BITMASK;
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if (oldval == newval)
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break;
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if (atomic_compare_exchange_weak_acquire (&self->cancelhandling,
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&oldval, newval))
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break;
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}
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__do_cancel (PTHREAD_CANCELED);
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}
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