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/* Thread cancellation support.
Copyright (C) 1995-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <hurd/signal.h>
#include <hurd/interrupt.h>
#include <assert.h>
#include <thread_state.h>
/* See hurdsig.c. */
extern mach_port_t _hurdsig_abort_rpcs (struct hurd_sigstate *ss,
int signo, int sigthread,
struct machine_thread_all_state *,
int *state_change,
mach_port_t *reply_port,
mach_msg_type_name_t reply_port_type,
int untraced);
error_t
hurd_thread_cancel (thread_t thread)
{
struct hurd_sigstate *ss = _hurd_thread_sigstate (thread);
struct machine_thread_all_state state;
int state_change;
error_t err;
if (! ss)
return EINVAL;
if (ss == _hurd_self_sigstate ())
{
/* We are cancelling ourselves, so it is easy to succeed
quickly. Since this function is not a cancellation point, we
just leave the flag set pending the next cancellation point
(hurd_check_cancel or RPC) and return success. */
ss->cancel = 1;
return 0;
}
assert (! __spin_lock_locked (&ss->critical_section_lock));
__spin_lock (&ss->critical_section_lock);
__spin_lock (&ss->lock);
err = __thread_suspend (thread);
__spin_unlock (&ss->lock);
if (! err)
{
/* Set the flag telling the thread its operation is being cancelled. */
ss->cancel = 1;
/* Interrupt any interruptible RPC now in progress. */
state.set = 0;
_hurdsig_abort_rpcs (ss, 0, 0, &state, &state_change, NULL, 0, 0);
if (state_change)
err = __thread_set_state (thread, MACHINE_THREAD_STATE_FLAVOR,
(natural_t *) &state.basic,
MACHINE_THREAD_STATE_COUNT);
if (ss->cancel_hook)
/* The code being cancelled has a special wakeup function.
Calling this should make the thread wake up and check the
cancellation flag. */
(*ss->cancel_hook) ();
__thread_resume (thread);
}
_hurd_critical_section_unlock (ss);
return err;
}
int
hurd_check_cancel (void)
{
struct hurd_sigstate *ss = _hurd_self_sigstate ();
int cancel;
__spin_lock (&ss->lock);
assert (! __spin_lock_locked (&ss->critical_section_lock));
cancel = ss->cancel;
ss->cancel = 0;
__spin_unlock (&ss->lock);
return cancel;
}
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