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264 lines
8.2 KiB
C
264 lines
8.2 KiB
C
/* Copyright (C) 2002-2007, 2008, 2010 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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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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<http://www.gnu.org/licenses/>. */
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#include <sched.h>
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#include <setjmp.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <atomic.h>
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#include <ldsodefs.h>
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#include <tls.h>
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#include "kernel-features.h"
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#define CLONE_SIGNAL (CLONE_SIGHAND | CLONE_THREAD)
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/* Unless otherwise specified, the thread "register" is going to be
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initialized with a pointer to the TCB. */
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#ifndef TLS_VALUE
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# define TLS_VALUE pd
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#endif
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#ifndef ARCH_CLONE
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# define ARCH_CLONE __clone
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#endif
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#ifndef TLS_MULTIPLE_THREADS_IN_TCB
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/* Pointer to the corresponding variable in libc. */
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int *__libc_multiple_threads_ptr attribute_hidden;
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#endif
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static int
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do_clone (struct pthread *pd, const struct pthread_attr *attr,
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int clone_flags, int (*fct) (void *), STACK_VARIABLES_PARMS,
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int stopped)
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{
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#ifdef PREPARE_CREATE
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PREPARE_CREATE;
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#endif
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if (__builtin_expect (stopped != 0, 0))
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/* We make sure the thread does not run far by forcing it to get a
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lock. We lock it here too so that the new thread cannot continue
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until we tell it to. */
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lll_lock (pd->lock, LLL_PRIVATE);
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/* One more thread. We cannot have the thread do this itself, since it
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might exist but not have been scheduled yet by the time we've returned
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and need to check the value to behave correctly. We must do it before
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creating the thread, in case it does get scheduled first and then
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might mistakenly think it was the only thread. In the failure case,
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we momentarily store a false value; this doesn't matter because there
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is no kosher thing a signal handler interrupting us right here can do
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that cares whether the thread count is correct. */
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atomic_increment (&__nptl_nthreads);
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int rc = ARCH_CLONE (fct, STACK_VARIABLES_ARGS, clone_flags,
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pd, &pd->tid, TLS_VALUE, &pd->tid);
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if (__builtin_expect (rc == -1, 0))
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{
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atomic_decrement (&__nptl_nthreads); /* Oops, we lied for a second. */
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/* Perhaps a thread wants to change the IDs and if waiting
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for this stillborn thread. */
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if (__builtin_expect (atomic_exchange_acq (&pd->setxid_futex, 0)
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== -2, 0))
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lll_futex_wake (&pd->setxid_futex, 1, LLL_PRIVATE);
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/* Free the resources. */
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__deallocate_stack (pd);
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/* We have to translate error codes. */
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return errno == ENOMEM ? EAGAIN : errno;
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}
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/* Now we have the possibility to set scheduling parameters etc. */
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if (__builtin_expect (stopped != 0, 0))
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{
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INTERNAL_SYSCALL_DECL (err);
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int res = 0;
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/* Set the affinity mask if necessary. */
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if (attr->cpuset != NULL)
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{
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res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid,
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attr->cpusetsize, attr->cpuset);
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if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
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{
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/* The operation failed. We have to kill the thread. First
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send it the cancellation signal. */
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INTERNAL_SYSCALL_DECL (err2);
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err_out:
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#if __ASSUME_TGKILL
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(void) INTERNAL_SYSCALL (tgkill, err2, 3,
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THREAD_GETMEM (THREAD_SELF, pid),
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pd->tid, SIGCANCEL);
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#else
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(void) INTERNAL_SYSCALL (tkill, err2, 2, pd->tid, SIGCANCEL);
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#endif
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/* We do not free the stack here because the canceled thread
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itself will do this. */
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return (INTERNAL_SYSCALL_ERROR_P (res, err)
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? INTERNAL_SYSCALL_ERRNO (res, err)
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: 0);
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}
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}
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/* Set the scheduling parameters. */
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if ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0)
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{
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res = INTERNAL_SYSCALL (sched_setscheduler, err, 3, pd->tid,
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pd->schedpolicy, &pd->schedparam);
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if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
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goto err_out;
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}
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}
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/* We now have for sure more than one thread. The main thread might
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not yet have the flag set. No need to set the global variable
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again if this is what we use. */
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THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
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return 0;
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}
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static int
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create_thread (struct pthread *pd, const struct pthread_attr *attr,
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STACK_VARIABLES_PARMS)
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{
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#ifdef TLS_TCB_AT_TP
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assert (pd->header.tcb != NULL);
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#endif
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/* We rely heavily on various flags the CLONE function understands:
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CLONE_VM, CLONE_FS, CLONE_FILES
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These flags select semantics with shared address space and
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file descriptors according to what POSIX requires.
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CLONE_SIGNAL
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This flag selects the POSIX signal semantics.
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CLONE_SETTLS
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The sixth parameter to CLONE determines the TLS area for the
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new thread.
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CLONE_PARENT_SETTID
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The kernels writes the thread ID of the newly created thread
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into the location pointed to by the fifth parameters to CLONE.
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Note that it would be semantically equivalent to use
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CLONE_CHILD_SETTID but it is be more expensive in the kernel.
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CLONE_CHILD_CLEARTID
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The kernels clears the thread ID of a thread that has called
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sys_exit() in the location pointed to by the seventh parameter
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to CLONE.
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CLONE_DETACHED
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No signal is generated if the thread exists and it is
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automatically reaped.
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The termination signal is chosen to be zero which means no signal
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is sent. */
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int clone_flags = (CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGNAL
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| CLONE_SETTLS | CLONE_PARENT_SETTID
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| CLONE_CHILD_CLEARTID | CLONE_SYSVSEM
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#if __ASSUME_NO_CLONE_DETACHED == 0
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| CLONE_DETACHED
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#endif
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| 0);
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if (__builtin_expect (THREAD_GETMEM (THREAD_SELF, report_events), 0))
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{
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/* The parent thread is supposed to report events. Check whether
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the TD_CREATE event is needed, too. */
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const int _idx = __td_eventword (TD_CREATE);
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const uint32_t _mask = __td_eventmask (TD_CREATE);
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if ((_mask & (__nptl_threads_events.event_bits[_idx]
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| pd->eventbuf.eventmask.event_bits[_idx])) != 0)
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{
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/* We always must have the thread start stopped. */
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pd->stopped_start = true;
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/* Create the thread. We always create the thread stopped
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so that it does not get far before we tell the debugger. */
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int res = do_clone (pd, attr, clone_flags, start_thread,
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STACK_VARIABLES_ARGS, 1);
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if (res == 0)
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{
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/* Now fill in the information about the new thread in
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the newly created thread's data structure. We cannot let
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the new thread do this since we don't know whether it was
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already scheduled when we send the event. */
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pd->eventbuf.eventnum = TD_CREATE;
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pd->eventbuf.eventdata = pd;
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/* Enqueue the descriptor. */
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do
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pd->nextevent = __nptl_last_event;
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while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event,
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pd, pd->nextevent)
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!= 0);
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/* Now call the function which signals the event. */
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__nptl_create_event ();
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/* And finally restart the new thread. */
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lll_unlock (pd->lock, LLL_PRIVATE);
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}
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return res;
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}
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}
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#ifdef NEED_DL_SYSINFO
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assert (THREAD_SELF_SYSINFO == THREAD_SYSINFO (pd));
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#endif
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/* Determine whether the newly created threads has to be started
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stopped since we have to set the scheduling parameters or set the
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affinity. */
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bool stopped = false;
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if (attr != NULL && (attr->cpuset != NULL
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|| (attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0))
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stopped = true;
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pd->stopped_start = stopped;
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pd->parent_cancelhandling = THREAD_GETMEM (THREAD_SELF, cancelhandling);
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/* Actually create the thread. */
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int res = do_clone (pd, attr, clone_flags, start_thread,
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STACK_VARIABLES_ARGS, stopped);
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if (res == 0 && stopped)
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/* And finally restart the new thread. */
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lll_unlock (pd->lock, LLL_PRIVATE);
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return res;
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}
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