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32fed10f | 1 | /* Low-level thread creation for NPTL. Linux version. |
04277e02 | 2 | Copyright (C) 2002-2019 Free Software Foundation, Inc. |
e6ebd2e4 UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Lesser General Public | |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 | 17 | License along with the GNU C Library; if not, see |
5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
e6ebd2e4 UD |
19 | |
20 | #include <sched.h> | |
21 | #include <setjmp.h> | |
22 | #include <signal.h> | |
23 | #include <stdlib.h> | |
24 | #include <atomic.h> | |
25 | #include <ldsodefs.h> | |
26 | #include <tls.h> | |
e054f494 | 27 | #include <stdint.h> |
e6ebd2e4 | 28 | |
ca08746f RM |
29 | #include <arch-fork.h> |
30 | ||
3dc21497 AZ |
31 | #ifdef __NR_clone2 |
32 | # define ARCH_CLONE __clone2 | |
33 | #else | |
5d5d5969 RM |
34 | # define ARCH_CLONE __clone |
35 | #endif | |
36 | ||
32fed10f RM |
37 | /* See the comments in pthread_create.c for the requirements for these |
38 | two macros and the create_thread function. */ | |
39 | ||
40 | #define START_THREAD_DEFN \ | |
41 | static int __attribute__ ((noreturn)) start_thread (void *arg) | |
42 | #define START_THREAD_SELF arg | |
43 | ||
44 | /* pthread_create.c defines this using START_THREAD_DEFN | |
45 | We need a forward declaration here so we can take its address. */ | |
46 | static int start_thread (void *arg) __attribute__ ((noreturn)); | |
e6ebd2e4 UD |
47 | |
48 | static int | |
32fed10f | 49 | create_thread (struct pthread *pd, const struct pthread_attr *attr, |
f8bf15fe | 50 | bool *stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran) |
e6ebd2e4 | 51 | { |
32fed10f RM |
52 | /* Determine whether the newly created threads has to be started |
53 | stopped since we have to set the scheduling parameters or set the | |
54 | affinity. */ | |
55 | if (attr != NULL | |
56 | && (__glibc_unlikely (attr->cpuset != NULL) | |
57 | || __glibc_unlikely ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0))) | |
f8bf15fe | 58 | *stopped_start = true; |
e6ebd2e4 | 59 | |
f8bf15fe CD |
60 | pd->stopped_start = *stopped_start; |
61 | if (__glibc_unlikely (*stopped_start)) | |
62 | /* See CONCURRENCY NOTES in nptl/pthread_creat.c. */ | |
e51deae7 | 63 | lll_lock (pd->lock, LLL_PRIVATE); |
f1205aa7 | 64 | |
32fed10f | 65 | /* We rely heavily on various flags the CLONE function understands: |
fd5d6a62 | 66 | |
32fed10f RM |
67 | CLONE_VM, CLONE_FS, CLONE_FILES |
68 | These flags select semantics with shared address space and | |
69 | file descriptors according to what POSIX requires. | |
66f1b8ee | 70 | |
32fed10f RM |
71 | CLONE_SIGHAND, CLONE_THREAD |
72 | This flag selects the POSIX signal semantics and various | |
73 | other kinds of sharing (itimers, POSIX timers, etc.). | |
fd5d6a62 | 74 | |
32fed10f RM |
75 | CLONE_SETTLS |
76 | The sixth parameter to CLONE determines the TLS area for the | |
77 | new thread. | |
1d78f299 | 78 | |
32fed10f RM |
79 | CLONE_PARENT_SETTID |
80 | The kernels writes the thread ID of the newly created thread | |
81 | into the location pointed to by the fifth parameters to CLONE. | |
3f80a99b | 82 | |
32fed10f RM |
83 | Note that it would be semantically equivalent to use |
84 | CLONE_CHILD_SETTID but it is be more expensive in the kernel. | |
85 | ||
86 | CLONE_CHILD_CLEARTID | |
87 | The kernels clears the thread ID of a thread that has called | |
88 | sys_exit() in the location pointed to by the seventh parameter | |
89 | to CLONE. | |
90 | ||
91 | The termination signal is chosen to be zero which means no signal | |
92 | is sent. */ | |
93 | const int clone_flags = (CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SYSVSEM | |
94 | | CLONE_SIGHAND | CLONE_THREAD | |
95 | | CLONE_SETTLS | CLONE_PARENT_SETTID | |
96 | | CLONE_CHILD_CLEARTID | |
97 | | 0); | |
98 | ||
99 | TLS_DEFINE_INIT_TP (tp, pd); | |
100 | ||
101 | if (__glibc_unlikely (ARCH_CLONE (&start_thread, STACK_VARIABLES_ARGS, | |
102 | clone_flags, pd, &pd->tid, tp, &pd->tid) | |
103 | == -1)) | |
104 | return errno; | |
105 | ||
106 | /* It's started now, so if we fail below, we'll have to cancel it | |
107 | and let it clean itself up. */ | |
108 | *thread_ran = true; | |
e6ebd2e4 | 109 | |
80f536db | 110 | /* Now we have the possibility to set scheduling parameters etc. */ |
32fed10f | 111 | if (attr != NULL) |
e6ebd2e4 | 112 | { |
80f536db | 113 | INTERNAL_SYSCALL_DECL (err); |
32fed10f | 114 | int res; |
e6ebd2e4 | 115 | |
80f536db UD |
116 | /* Set the affinity mask if necessary. */ |
117 | if (attr->cpuset != NULL) | |
e6ebd2e4 | 118 | { |
f8bf15fe | 119 | assert (*stopped_start); |
32fed10f | 120 | |
80f536db | 121 | res = INTERNAL_SYSCALL (sched_setaffinity, err, 3, pd->tid, |
7c0ad164 | 122 | attr->cpusetsize, attr->cpuset); |
e6ebd2e4 | 123 | |
a1ffb40e | 124 | if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err))) |
32fed10f | 125 | err_out: |
9c988b83 | 126 | { |
32fed10f RM |
127 | /* The operation failed. We have to kill the thread. |
128 | We let the normal cancellation mechanism do the work. */ | |
129 | ||
c579f48e | 130 | pid_t pid = __getpid (); |
9c988b83 | 131 | INTERNAL_SYSCALL_DECL (err2); |
c579f48e AZ |
132 | (void) INTERNAL_SYSCALL_CALL (tgkill, err2, pid, pd->tid, |
133 | SIGCANCEL); | |
9c988b83 | 134 | |
32fed10f | 135 | return INTERNAL_SYSCALL_ERRNO (res, err); |
9c988b83 | 136 | } |
80f536db UD |
137 | } |
138 | ||
139 | /* Set the scheduling parameters. */ | |
140 | if ((attr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0) | |
141 | { | |
f8bf15fe | 142 | assert (*stopped_start); |
32fed10f | 143 | |
5c5252bd UD |
144 | res = INTERNAL_SYSCALL (sched_setscheduler, err, 3, pd->tid, |
145 | pd->schedpolicy, &pd->schedparam); | |
80f536db | 146 | |
a1ffb40e | 147 | if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err))) |
5c5252bd | 148 | goto err_out; |
80f536db | 149 | } |
e6ebd2e4 UD |
150 | } |
151 | ||
80f536db UD |
152 | return 0; |
153 | } |