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NPTL: Refactor createthread.c

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This commit is contained in:
Roland McGrath
2014-11-18 11:03:00 -08:00
parent 107a5bf085
commit 32fed10f0f
3 changed files with 240 additions and 169 deletions
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232
nptl/createthread.c
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@ -1,4 +1,5 @@
/* Copyright (C) 2002-2014 Free Software Foundation, Inc.
/* Low-level thread creation for NPTL. Linux version.
Copyright (C) 2002-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
@ -28,124 +29,49 @@
#include <arch-fork.h>
#define CLONE_SIGNAL (CLONE_SIGHAND | CLONE_THREAD)
#ifndef ARCH_CLONE
# define ARCH_CLONE __clone
#endif
/* See the comments in pthread_create.c for the requirements for these
two macros and the create_thread function. */
#define START_THREAD_DEFN \
static int __attribute__ ((noreturn)) start_thread (void *arg)
#define START_THREAD_SELF arg
/* pthread_create.c defines this using START_THREAD_DEFN
We need a forward declaration here so we can take its address. */
static int start_thread (void *arg) __attribute__ ((noreturn));
static int
do_clone (struct pthread *pd, const struct pthread_attr *attr,
int clone_flags, int (*fct) (void *), STACK_VARIABLES_PARMS,
int stopped)
create_thread (struct pthread *pd, const struct pthread_attr *attr,
bool stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran)
{
TLS_DEFINE_INIT_TP (tp, pd);
/* Determine whether the newly created threads has to be started
stopped since we have to set the scheduling parameters or set the
affinity. */
if (attr != NULL
&& (__glibc_unlikely (attr->cpuset != NULL)
|| __glibc_unlikely ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0)))
stopped_start = true;
if (__glibc_unlikely (stopped != 0))
pd->stopped_start = stopped_start;
if (__glibc_unlikely (stopped_start))
/* 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, LLL_PRIVATE);
/* 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);
int rc = ARCH_CLONE (fct, STACK_VARIABLES_ARGS, clone_flags,
pd, &pd->tid, tp, &pd->tid);
if (__glibc_unlikely (rc == -1))
{
atomic_decrement (&__nptl_nthreads); /* Oops, we lied for a second. */
/* Perhaps a thread wants to change the IDs and if waiting
for this stillborn thread. */
if (__builtin_expect (atomic_exchange_acq (&pd->setxid_futex, 0)
== -2, 0))
lll_futex_wake (&pd->setxid_futex, 1, LLL_PRIVATE);
/* Free the resources. */
__deallocate_stack (pd);
/* We have to translate error codes. */
return errno == ENOMEM ? EAGAIN : errno;
}
/* Now we have the possibility to set scheduling parameters etc. */
if (__glibc_unlikely (stopped != 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,
attr->cpusetsize, attr->cpuset);
if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err)))
{
/* The operation failed. We have to kill the thread. First
send it the cancellation signal. */
INTERNAL_SYSCALL_DECL (err2);
err_out:
(void) INTERNAL_SYSCALL (tgkill, err2, 3,
THREAD_GETMEM (THREAD_SELF, pid),
pd->tid, SIGCANCEL);
/* We do not free the stack here because the canceled thread
itself will do this. */
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 (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err)))
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)
{
#if 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_SIGHAND, CLONE_THREAD
This flag selects the POSIX signal semantics and various
other kinds of sharing (itimers, POSIX timers, etc.).
CLONE_SETTLS
The sixth parameter to CLONE determines the TLS area for the
@ -165,76 +91,64 @@ create_thread (struct pthread *pd, const struct pthread_attr *attr,
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
| 0);
const int clone_flags = (CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SYSVSEM
| CLONE_SIGHAND | CLONE_THREAD
| CLONE_SETTLS | CLONE_PARENT_SETTID
| CLONE_CHILD_CLEARTID
| 0);
if (__glibc_unlikely (THREAD_GETMEM (THREAD_SELF, report_events)))
TLS_DEFINE_INIT_TP (tp, pd);
if (__glibc_unlikely (ARCH_CLONE (&start_thread, STACK_VARIABLES_ARGS,
clone_flags, pd, &pd->tid, tp, &pd->tid)
== -1))
return errno;
/* It's started now, so if we fail below, we'll have to cancel it
and let it clean itself up. */
*thread_ran = true;
/* Now we have the possibility to set scheduling parameters etc. */
if (attr != NULL)
{
/* 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);
INTERNAL_SYSCALL_DECL (err);
int res;
if ((_mask & (__nptl_threads_events.event_bits[_idx]
| pd->eventbuf.eventmask.event_bits[_idx])) != 0)
/* Set the affinity mask if necessary. */
if (attr->cpuset != NULL)
{
/* We always must have the thread start stopped. */
pd->stopped_start = true;
assert (stopped_start);
/* 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)
res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid,
attr->cpusetsize, attr->cpuset);
if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err)))
err_out:
{
/* 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;
/* The operation failed. We have to kill the thread.
We let the normal cancellation mechanism do the work. */
/* Enqueue the descriptor. */
do
pd->nextevent = __nptl_last_event;
while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event,
pd, pd->nextevent)
!= 0);
INTERNAL_SYSCALL_DECL (err2);
(void) INTERNAL_SYSCALL (tgkill, err2, 3,
THREAD_GETMEM (THREAD_SELF, pid),
pd->tid, SIGCANCEL);
/* Now call the function which signals the event. */
__nptl_create_event ();
/* And finally restart the new thread. */
lll_unlock (pd->lock, LLL_PRIVATE);
return INTERNAL_SYSCALL_ERRNO (res, err);
}
}
return res;
/* Set the scheduling parameters. */
if ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0)
{
assert (stopped_start);
res = INTERNAL_SYSCALL (sched_setscheduler, err, 3, pd->tid,
pd->schedpolicy, &pd->schedparam);
if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err)))
goto err_out;
}
}
#ifdef NEED_DL_SYSINFO
CHECK_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;
pd->parent_cancelhandling = THREAD_GETMEM (THREAD_SELF, cancelhandling);
/* 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, LLL_PRIVATE);
return res;
return 0;
}