diff options
Diffstat (limited to 'nptl/createthread.c')
| -rw-r--r-- | nptl/createthread.c | 232 |
1 files changed, 73 insertions, 159 deletions
diff --git a/nptl/createthread.c b/nptl/createthread.c index 49442d9f23..7b05d48954 100644 --- a/nptl/createthread.c +++ b/nptl/createthread.c @@ -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. @@ -28,91 +29,119 @@ #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); + /* We rely heavily on various flags the CLONE function understands: - int rc = ARCH_CLONE (fct, STACK_VARIABLES_ARGS, clone_flags, - pd, &pd->tid, tp, &pd->tid); + CLONE_VM, CLONE_FS, CLONE_FILES + These flags select semantics with shared address space and + file descriptors according to what POSIX requires. - if (__glibc_unlikely (rc == -1)) - { - atomic_decrement (&__nptl_nthreads); /* Oops, we lied for a second. */ + CLONE_SIGHAND, CLONE_THREAD + This flag selects the POSIX signal semantics and various + other kinds of sharing (itimers, POSIX timers, etc.). - /* 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); + CLONE_SETTLS + The sixth parameter to CLONE determines the TLS area for the + new thread. - /* Free the resources. */ - __deallocate_stack (pd); + 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. - /* We have to translate error codes. */ - return errno == ENOMEM ? EAGAIN : errno; - } + 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. + + The termination signal is chosen to be zero which means no signal + is sent. */ + 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); + + 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 (__glibc_unlikely (stopped != 0)) + if (attr != NULL) { INTERNAL_SYSCALL_DECL (err); - int res = 0; + int res; /* Set the affinity mask if necessary. */ if (attr->cpuset != NULL) { + assert (stopped_start); + res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid, attr->cpusetsize, attr->cpuset); if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err))) + err_out: { - /* The operation failed. We have to kill the thread. First - send it the cancellation signal. */ + /* The operation failed. We have to kill the thread. + We let the normal cancellation mechanism do the work. */ + 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); + return INTERNAL_SYSCALL_ERRNO (res, err); } } /* 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); @@ -121,120 +150,5 @@ do_clone (struct pthread *pd, const struct pthread_attr *attr, } } - /* 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_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. - - 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); - - if (__glibc_unlikely (THREAD_GETMEM (THREAD_SELF, report_events))) - { - /* 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, LLL_PRIVATE); - } - - return res; - } - } - -#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; -} |