diff options
Diffstat (limited to 'sysdeps/nptl')
| -rw-r--r-- | sysdeps/nptl/fork.c | 238 | ||||
| -rw-r--r-- | sysdeps/nptl/fork.h | 59 | ||||
| -rw-r--r-- | sysdeps/nptl/jmp-unwind.c | 38 | ||||
| -rw-r--r-- | sysdeps/nptl/lowlevellock.h | 83 |
4 files changed, 418 insertions, 0 deletions
diff --git a/sysdeps/nptl/fork.c b/sysdeps/nptl/fork.c new file mode 100644 index 0000000000..70201a294c --- /dev/null +++ b/sysdeps/nptl/fork.c @@ -0,0 +1,238 @@ +/* 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. + + 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 + <http://www.gnu.org/licenses/>. */ + +#include <assert.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/types.h> +#include <sysdep.h> +#include <libio/libioP.h> +#include <tls.h> +#include <hp-timing.h> +#include <ldsodefs.h> +#include <bits/stdio-lock.h> +#include <atomic.h> +#include <pthreadP.h> +#include <fork.h> +#include <arch-fork.h> + + +unsigned long int *__fork_generation_pointer; + + + +/* The single linked list of all currently registered fork handlers. */ +struct fork_handler *__fork_handlers; + + +static void +fresetlockfiles (void) +{ + _IO_ITER i; + + for (i = _IO_iter_begin(); i != _IO_iter_end(); i = _IO_iter_next(i)) + _IO_lock_init (*((_IO_lock_t *) _IO_iter_file(i)->_lock)); +} + + +pid_t +__libc_fork (void) +{ + pid_t pid; + struct used_handler + { + struct fork_handler *handler; + struct used_handler *next; + } *allp = NULL; + + /* Run all the registered preparation handlers. In reverse order. + While doing this we build up a list of all the entries. */ + struct fork_handler *runp; + while ((runp = __fork_handlers) != NULL) + { + /* Make sure we read from the current RUNP pointer. */ + atomic_full_barrier (); + + unsigned int oldval = runp->refcntr; + + if (oldval == 0) + /* This means some other thread removed the list just after + the pointer has been loaded. Try again. Either the list + is empty or we can retry it. */ + continue; + + /* Bump the reference counter. */ + if (atomic_compare_and_exchange_bool_acq (&__fork_handlers->refcntr, + oldval + 1, oldval)) + /* The value changed, try again. */ + continue; + + /* We bumped the reference counter for the first entry in the + list. That means that none of the following entries will + just go away. The unloading code works in the order of the + list. + + While executing the registered handlers we are building a + list of all the entries so that we can go backward later on. */ + while (1) + { + /* Execute the handler if there is one. */ + if (runp->prepare_handler != NULL) + runp->prepare_handler (); + + /* Create a new element for the list. */ + struct used_handler *newp + = (struct used_handler *) alloca (sizeof (*newp)); + newp->handler = runp; + newp->next = allp; + allp = newp; + + /* Advance to the next handler. */ + runp = runp->next; + if (runp == NULL) + break; + + /* Bump the reference counter for the next entry. */ + atomic_increment (&runp->refcntr); + } + + /* We are done. */ + break; + } + + _IO_list_lock (); + +#ifndef NDEBUG + pid_t ppid = THREAD_GETMEM (THREAD_SELF, tid); +#endif + + /* We need to prevent the getpid() code to update the PID field so + that, if a signal arrives in the child very early and the signal + handler uses getpid(), the value returned is correct. */ + pid_t parentpid = THREAD_GETMEM (THREAD_SELF, pid); + THREAD_SETMEM (THREAD_SELF, pid, -parentpid); + +#ifdef ARCH_FORK + pid = ARCH_FORK (); +#else +# error "ARCH_FORK must be defined so that the CLONE_SETTID flag is used" + pid = INLINE_SYSCALL (fork, 0); +#endif + + + if (pid == 0) + { + struct pthread *self = THREAD_SELF; + + assert (THREAD_GETMEM (self, tid) != ppid); + + if (__fork_generation_pointer != NULL) + *__fork_generation_pointer += 4; + + /* Adjust the PID field for the new process. */ + THREAD_SETMEM (self, pid, THREAD_GETMEM (self, tid)); + +#if HP_TIMING_AVAIL + /* The CPU clock of the thread and process have to be set to zero. */ + hp_timing_t now; + HP_TIMING_NOW (now); + THREAD_SETMEM (self, cpuclock_offset, now); + GL(dl_cpuclock_offset) = now; +#endif + +#ifdef __NR_set_robust_list + /* Initialize the robust mutex list which has been reset during + the fork. We do not check for errors since if it fails here + it failed at process start as well and noone could have used + robust mutexes. We also do not have to set + self->robust_head.futex_offset since we inherit the correct + value from the parent. */ +# ifdef SHARED + if (__builtin_expect (__libc_pthread_functions_init, 0)) + PTHFCT_CALL (ptr_set_robust, (self)); +# else + extern __typeof (__nptl_set_robust) __nptl_set_robust + __attribute__((weak)); + if (__builtin_expect (__nptl_set_robust != NULL, 0)) + __nptl_set_robust (self); +# endif +#endif + + /* Reset the file list. These are recursive mutexes. */ + fresetlockfiles (); + + /* Reset locks in the I/O code. */ + _IO_list_resetlock (); + + /* Reset the lock the dynamic loader uses to protect its data. */ + __rtld_lock_initialize (GL(dl_load_lock)); + + /* Run the handlers registered for the child. */ + while (allp != NULL) + { + if (allp->handler->child_handler != NULL) + allp->handler->child_handler (); + + /* Note that we do not have to wake any possible waiter. + This is the only thread in the new process. The count + may have been bumped up by other threads doing a fork. + We reset it to 1, to avoid waiting for non-existing + thread(s) to release the count. */ + allp->handler->refcntr = 1; + + /* XXX We could at this point look through the object pool + and mark all objects not on the __fork_handlers list as + unused. This is necessary in case the fork() happened + while another thread called dlclose() and that call had + to create a new list. */ + + allp = allp->next; + } + + /* Initialize the fork lock. */ + __fork_lock = LLL_LOCK_INITIALIZER; + } + else + { + assert (THREAD_GETMEM (THREAD_SELF, tid) == ppid); + + /* Restore the PID value. */ + THREAD_SETMEM (THREAD_SELF, pid, parentpid); + + /* We execute this even if the 'fork' call failed. */ + _IO_list_unlock (); + + /* Run the handlers registered for the parent. */ + while (allp != NULL) + { + if (allp->handler->parent_handler != NULL) + allp->handler->parent_handler (); + + if (atomic_decrement_and_test (&allp->handler->refcntr) + && allp->handler->need_signal) + lll_futex_wake (allp->handler->refcntr, 1, LLL_PRIVATE); + + allp = allp->next; + } + } + + return pid; +} +weak_alias (__libc_fork, __fork) +libc_hidden_def (__fork) +weak_alias (__libc_fork, fork) diff --git a/sysdeps/nptl/fork.h b/sysdeps/nptl/fork.h new file mode 100644 index 0000000000..8e28a76098 --- /dev/null +++ b/sysdeps/nptl/fork.h @@ -0,0 +1,59 @@ +/* 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. + + 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 + <http://www.gnu.org/licenses/>. */ + +#include <lowlevellock.h> + +/* The fork generation counter, defined in libpthread. */ +extern unsigned long int __fork_generation attribute_hidden; + +/* Pointer to the fork generation counter in the thread library. */ +extern unsigned long int *__fork_generation_pointer attribute_hidden; + +/* Lock to protect allocation and deallocation of fork handlers. */ +extern int __fork_lock attribute_hidden; + +/* Elements of the fork handler lists. */ +struct fork_handler +{ + struct fork_handler *next; + void (*prepare_handler) (void); + void (*parent_handler) (void); + void (*child_handler) (void); + void *dso_handle; + unsigned int refcntr; + int need_signal; +}; + +/* The single linked list of all currently registered for handlers. */ +extern struct fork_handler *__fork_handlers attribute_hidden; + + +/* Function to call to unregister fork handlers. */ +extern void __unregister_atfork (void *dso_handle) attribute_hidden; +#define UNREGISTER_ATFORK(dso_handle) __unregister_atfork (dso_handle) + + +/* C library side function to register new fork handlers. */ +extern int __register_atfork (void (*__prepare) (void), + void (*__parent) (void), + void (*__child) (void), + void *dso_handle); +libc_hidden_proto (__register_atfork) + +/* Add a new element to the fork list. */ +extern void __linkin_atfork (struct fork_handler *newp) attribute_hidden; diff --git a/sysdeps/nptl/jmp-unwind.c b/sysdeps/nptl/jmp-unwind.c new file mode 100644 index 0000000000..b3a960c980 --- /dev/null +++ b/sysdeps/nptl/jmp-unwind.c @@ -0,0 +1,38 @@ +/* Clean up stack frames unwound by longjmp. Linux version. + Copyright (C) 1995-2014 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 + <http://www.gnu.org/licenses/>. */ + +#include <setjmp.h> +#include <stddef.h> +#include <pthreadP.h> + +extern void __pthread_cleanup_upto (__jmp_buf env, char *targetframe); +#pragma weak __pthread_cleanup_upto + + +void +_longjmp_unwind (jmp_buf env, int val) +{ +#ifdef SHARED + if (__libc_pthread_functions_init) + PTHFCT_CALL (ptr___pthread_cleanup_upto, (env->__jmpbuf, + CURRENT_STACK_FRAME)); +#else + if (__pthread_cleanup_upto != NULL) + __pthread_cleanup_upto (env->__jmpbuf, CURRENT_STACK_FRAME); +#endif +} diff --git a/sysdeps/nptl/lowlevellock.h b/sysdeps/nptl/lowlevellock.h new file mode 100644 index 0000000000..7d1913a58d --- /dev/null +++ b/sysdeps/nptl/lowlevellock.h @@ -0,0 +1,83 @@ +/* Low level locking macros used in NPTL implementation. Stub 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. + + 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 + <http://www.gnu.org/licenses/>. */ + +#include <atomic.h> + + +/* Mutex lock counter: + bit 31 clear means unlocked; + bit 31 set means locked. + + All code that looks at bit 31 first increases the 'number of + interested threads' usage counter, which is in bits 0-30. + + All negative mutex values indicate that the mutex is still locked. */ + + +static inline void +__generic_mutex_lock (int *mutex) +{ + unsigned int v; + + /* Bit 31 was clear, we got the mutex. (this is the fastpath). */ + if (atomic_bit_test_set (mutex, 31) == 0) + return; + + atomic_increment (mutex); + + while (1) + { + if (atomic_bit_test_set (mutex, 31) == 0) + { + atomic_decrement (mutex); + return; + } + + /* We have to wait now. First make sure the futex value we are + monitoring is truly negative (i.e. locked). */ + v = *mutex; + if (v >= 0) + continue; + + lll_futex_wait (mutex, v, + // XYZ check mutex flag + LLL_SHARED); + } +} + + +static inline void +__generic_mutex_unlock (int *mutex) +{ + /* Adding 0x80000000 to the counter results in 0 if and only if + there are not other interested threads - we can return (this is + the fastpath). */ + if (atomic_add_zero (mutex, 0x80000000)) + return; + + /* There are other threads waiting for this mutex, wake one of them + up. */ + lll_futex_wake (mutex, 1, + // XYZ check mutex flag + LLL_SHARED); +} + + +#define lll_mutex_lock(futex) __generic_mutex_lock (&(futex)) +#define lll_mutex_unlock(futex) __generic_mutex_unlock (&(futex)) |