diff options
Diffstat (limited to 'libpthread/nptl/sysdeps/pthread/createthread.c')
| -rw-r--r-- | libpthread/nptl/sysdeps/pthread/createthread.c | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/libpthread/nptl/sysdeps/pthread/createthread.c b/libpthread/nptl/sysdeps/pthread/createthread.c new file mode 100644 index 000000000..88ffe09d3 --- /dev/null +++ b/libpthread/nptl/sysdeps/pthread/createthread.c @@ -0,0 +1,255 @@ +/* Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. + + 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, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <sched.h> +#include <setjmp.h> +#include <signal.h> +#include <stdlib.h> +#include <atomic.h> +#include <ldsodefs.h> +#include <tls.h> + +#include <bits/kernel-features.h> + + +#define CLONE_SIGNAL (CLONE_SIGHAND | CLONE_THREAD) + +/* Unless otherwise specified, the thread "register" is going to be + initialized with a pointer to the TCB. */ +#ifndef TLS_VALUE +# define TLS_VALUE pd +#endif + +#ifndef ARCH_CLONE +# define ARCH_CLONE __clone +#endif + + +#ifndef TLS_MULTIPLE_THREADS_IN_TCB +/* Pointer to the corresponding variable in libc. */ +int *__libc_multiple_threads_ptr attribute_hidden; +#endif + + +static int +do_clone (struct pthread *pd, const struct pthread_attr *attr, + int clone_flags, int (*fct) (void *), STACK_VARIABLES_PARMS, + int stopped) +{ +#ifdef PREPARE_CREATE + PREPARE_CREATE; +#endif + + if (stopped) + /* We Make sure the thread does not run far by forcing it to get a + lock. We lock it here too so that the new thread cannot continue + until we tell it to. */ + lll_lock (pd->lock); + + /* One more thread. We cannot have the thread do this itself, since it + might exist but not have been scheduled yet by the time we've returned + and need to check the value to behave correctly. We must do it before + creating the thread, in case it does get scheduled first and then + might mistakenly think it was the only thread. In the failure case, + we momentarily store a false value; this doesn't matter because there + is no kosher thing a signal handler interrupting us right here can do + that cares whether the thread count is correct. */ + atomic_increment (&__nptl_nthreads); + + if (ARCH_CLONE (fct, STACK_VARIABLES_ARGS, clone_flags, + pd, &pd->tid, TLS_VALUE, &pd->tid) == -1) + { + atomic_decrement (&__nptl_nthreads); /* Oops, we lied for a second. */ + + /* Failed. If the thread is detached, remove the TCB here since + the caller cannot do this. The caller remembered the thread + as detached and cannot reverify that it is not since it must + not access the thread descriptor again. */ + if (IS_DETACHED (pd)) + __deallocate_stack (pd); + + return errno; + } + + /* Now we have the possibility to set scheduling parameters etc. */ + if (__builtin_expect (stopped != 0, 0)) + { + INTERNAL_SYSCALL_DECL (err); + int res = 0; + + /* Set the affinity mask if necessary. */ + if (attr->cpuset != NULL) + { + res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid, + sizeof (cpu_set_t), attr->cpuset); + + if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0)) + { + /* The operation failed. We have to kill the thread. First + send it the cancellation signal. */ + INTERNAL_SYSCALL_DECL (err2); + err_out: +#if __ASSUME_TGKILL + (void) INTERNAL_SYSCALL (tgkill, err2, 3, + THREAD_GETMEM (THREAD_SELF, pid), + pd->tid, SIGCANCEL); +#else + (void) INTERNAL_SYSCALL (tkill, err2, 2, pd->tid, SIGCANCEL); +#endif + + return (INTERNAL_SYSCALL_ERROR_P (res, err) + ? INTERNAL_SYSCALL_ERRNO (res, err) + : 0); + } + } + + /* Set the scheduling parameters. */ + if ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0) + { + res = INTERNAL_SYSCALL (sched_setscheduler, err, 3, pd->tid, + pd->schedpolicy, &pd->schedparam); + + if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0)) + goto err_out; + } + } + + /* We now have for sure more than one thread. The main thread might + not yet have the flag set. No need to set the global variable + again if this is what we use. */ + THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1); + + return 0; +} + + +static int +create_thread (struct pthread *pd, const struct pthread_attr *attr, + STACK_VARIABLES_PARMS) +{ +#ifdef TLS_TCB_AT_TP + assert (pd->header.tcb != NULL); +#endif + + /* We rely heavily on various flags the CLONE function understands: + + CLONE_VM, CLONE_FS, CLONE_FILES + These flags select semantics with shared address space and + file descriptors according to what POSIX requires. + + CLONE_SIGNAL + This flag selects the POSIX signal semantics. + + CLONE_SETTLS + The sixth parameter to CLONE determines the TLS area for the + new thread. + + CLONE_PARENT_SETTID + The kernels writes the thread ID of the newly created thread + into the location pointed to by the fifth parameters to CLONE. + + Note that it would be semantically equivalent to use + CLONE_CHILD_SETTID but it is be more expensive in the kernel. + + CLONE_CHILD_CLEARTID + The kernels clears the thread ID of a thread that has called + sys_exit() in the location pointed to by the seventh parameter + to CLONE. + + CLONE_DETACHED + No signal is generated if the thread exists and it is + automatically reaped. + + The termination signal is chosen to be zero which means no signal + is sent. */ + int clone_flags = (CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGNAL + | CLONE_SETTLS | CLONE_PARENT_SETTID + | CLONE_CHILD_CLEARTID | CLONE_SYSVSEM +#if __ASSUME_NO_CLONE_DETACHED == 0 + | CLONE_DETACHED +#endif + | 0); + + if (__builtin_expect (THREAD_GETMEM (THREAD_SELF, report_events), 0)) + { + /* The parent thread is supposed to report events. Check whether + the TD_CREATE event is needed, too. */ + const int _idx = __td_eventword (TD_CREATE); + const uint32_t _mask = __td_eventmask (TD_CREATE); + + if ((_mask & (__nptl_threads_events.event_bits[_idx] + | pd->eventbuf.eventmask.event_bits[_idx])) != 0) + { + /* We always must have the thread start stopped. */ + pd->stopped_start = true; + + /* Create the thread. We always create the thread stopped + so that it does not get far before we tell the debugger. */ + int res = do_clone (pd, attr, clone_flags, start_thread, + STACK_VARIABLES_ARGS, 1); + if (res == 0) + { + /* Now fill in the information about the new thread in + the newly created thread's data structure. We cannot let + the new thread do this since we don't know whether it was + already scheduled when we send the event. */ + pd->eventbuf.eventnum = TD_CREATE; + pd->eventbuf.eventdata = pd; + + /* Enqueue the descriptor. */ + do + pd->nextevent = __nptl_last_event; + while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event, + pd, pd->nextevent) + != 0); + + /* Now call the function which signals the event. */ + __nptl_create_event (); + + /* And finally restart the new thread. */ + lll_unlock (pd->lock); + } + + return res; + } + } + +#ifdef NEED_DL_SYSINFO + assert (THREAD_SELF_SYSINFO == THREAD_SYSINFO (pd)); +#endif + + /* Determine whether the newly created threads has to be started + stopped since we have to set the scheduling parameters or set the + affinity. */ + bool stopped = false; + if (attr != NULL && (attr->cpuset != NULL + || (attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0)) + stopped = true; + pd->stopped_start = stopped; + + /* Actually create the thread. */ + int res = do_clone (pd, attr, clone_flags, start_thread, + STACK_VARIABLES_ARGS, stopped); + + if (res == 0 && stopped) + /* And finally restart the new thread. */ + lll_unlock (pd->lock); + + return res; +} |