Merging upstream version 6.8.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 395 insertions, 0 deletions

diff --git a/man/man3/pthread_create.3 b/man/man3/pthread_create.3
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+'\" t
+.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
+.\"     <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH pthread_create 3 2024-05-02 "Linux man-pages (unreleased)"
+.SH NAME
+pthread_create \- create a new thread
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <pthread.h>
+.P
+.BI "int pthread_create(pthread_t *restrict " thread ,
+.BI "                   const pthread_attr_t *restrict " attr ,
+.BI "                   void *(*" start_routine ")(void *),"
+.BI "                   void *restrict " arg );
+.fi
+.SH DESCRIPTION
+The
+.BR pthread_create ()
+function starts a new thread in the calling process.
+The new thread starts execution by invoking
+.IR start_routine ();
+.I arg
+is passed as the sole argument of
+.IR start_routine ().
+.P
+The new thread terminates in one of the following ways:
+.IP \[bu] 3
+It calls
+.BR pthread_exit (3),
+specifying an exit status value that is available to another thread
+in the same process that calls
+.BR pthread_join (3).
+.IP \[bu]
+It returns from
+.IR start_routine ().
+This is equivalent to calling
+.BR pthread_exit (3)
+with the value supplied in the
+.I return
+statement.
+.IP \[bu]
+It is canceled (see
+.BR pthread_cancel (3)).
+.IP \[bu]
+Any of the threads in the process calls
+.BR exit (3),
+or the main thread performs a return from
+.IR main ().
+This causes the termination of all threads in the process.
+.P
+The
+.I attr
+argument points to a
+.I pthread_attr_t
+structure whose contents are used at thread creation time to
+determine attributes for the new thread;
+this structure is initialized using
+.BR pthread_attr_init (3)
+and related functions.
+If
+.I attr
+is NULL,
+then the thread is created with default attributes.
+.P
+Before returning, a successful call to
+.BR pthread_create ()
+stores the ID of the new thread in the buffer pointed to by
+.IR thread ;
+this identifier is used to refer to the thread
+in subsequent calls to other pthreads functions.
+.P
+The new thread inherits a copy of the creating thread's signal mask
+.RB ( pthread_sigmask (3)).
+The set of pending signals for the new thread is empty
+.RB ( sigpending (2)).
+The new thread does not inherit the creating thread's
+alternate signal stack
+.RB ( sigaltstack (2)).
+.P
+The new thread inherits the calling thread's floating-point environment
+.RB ( fenv (3)).
+.P
+The initial value of the new thread's CPU-time clock is 0
+(see
+.BR pthread_getcpuclockid (3)).
+.\" CLOCK_THREAD_CPUTIME_ID in clock_gettime(2)
+.SS Linux-specific details
+The new thread inherits copies of the calling thread's capability sets
+(see
+.BR capabilities (7))
+and CPU affinity mask (see
+.BR sched_setaffinity (2)).
+.SH RETURN VALUE
+On success,
+.BR pthread_create ()
+returns 0;
+on error, it returns an error number, and the contents of
+.I *thread
+are undefined.
+.SH ERRORS
+.TP
+.B EAGAIN
+Insufficient resources to create another thread.
+.TP
+.B EAGAIN
+.\" NOTE! The following should match the description in fork(2)
+A system-imposed limit on the number of threads was encountered.
+There are a number of limits that may trigger this error: the
+.B RLIMIT_NPROC
+soft resource limit (set via
+.BR setrlimit (2)),
+which limits the number of processes and threads for a real user ID,
+was reached;
+the kernel's system-wide limit on the number of processes and threads,
+.IR /proc/sys/kernel/threads\-max ,
+was reached (see
+.BR proc (5));
+or the maximum number of PIDs,
+.IR /proc/sys/kernel/pid_max ,
+was reached (see
+.BR proc (5)).
+.TP
+.B EINVAL
+Invalid settings in
+.IR attr .
+.TP
+.\" FIXME . Test the following
+.B EPERM
+No permission to set the scheduling policy and parameters specified in
+.IR attr .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR pthread_create ()
+T}	Thread safety	MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+See
+.BR pthread_self (3)
+for further information on the thread ID returned in
+.I *thread
+by
+.BR pthread_create ().
+Unless real-time scheduling policies are being employed,
+after a call to
+.BR pthread_create (),
+it is indeterminate which thread\[em]the caller or the new thread\[em]will
+next execute.
+.P
+A thread may either be
+.I joinable
+or
+.IR detached .
+If a thread is joinable, then another thread can call
+.BR pthread_join (3)
+to wait for the thread to terminate and fetch its exit status.
+Only when a terminated joinable thread has been joined are
+the last of its resources released back to the system.
+When a detached thread terminates,
+its resources are automatically released back to the system:
+it is not possible to join with the thread in order to obtain
+its exit status.
+Making a thread detached is useful for some types of daemon threads
+whose exit status the application does not need to care about.
+By default, a new thread is created in a joinable state, unless
+.I attr
+was set to create the thread in a detached state (using
+.BR pthread_attr_setdetachstate (3)).
+.P
+Under the NPTL threading implementation, if the
+.B RLIMIT_STACK
+soft resource limit
+.I at the time the program started
+has any value other than "unlimited",
+then it determines the default stack size of new threads.
+Using
+.BR pthread_attr_setstacksize (3),
+the stack size attribute can be explicitly set in the
+.I attr
+argument used to create a thread,
+in order to obtain a stack size other than the default.
+If the
+.B RLIMIT_STACK
+resource limit is set to "unlimited",
+a per-architecture value is used for the stack size:
+2 MB on most architectures; 4 MB on POWER and Sparc-64.
+.SH BUGS
+In the obsolete LinuxThreads implementation,
+each of the threads in a process has a different process ID.
+This is in violation of the POSIX threads specification,
+and is the source of many other nonconformances to the standard; see
+.BR pthreads (7).
+.SH EXAMPLES
+The program below demonstrates the use of
+.BR pthread_create (),
+as well as a number of other functions in the pthreads API.
+.P
+In the following run,
+on a system providing the NPTL threading implementation,
+the stack size defaults to the value given by the
+"stack size" resource limit:
+.P
+.in +4n
+.EX
+.RB "$" " ulimit \-s"
+8192            # The stack size limit is 8 MB (0x800000 bytes)
+.RB "$" " ./a.out hola salut servus"
+Thread 1: top of stack near 0xb7dd03b8; argv_string=hola
+Thread 2: top of stack near 0xb75cf3b8; argv_string=salut
+Thread 3: top of stack near 0xb6dce3b8; argv_string=servus
+Joined with thread 1; returned value was HOLA
+Joined with thread 2; returned value was SALUT
+Joined with thread 3; returned value was SERVUS
+.EE
+.in
+.P
+In the next run, the program explicitly sets a stack size of 1\ MB (using
+.BR pthread_attr_setstacksize (3))
+for the created threads:
+.P
+.in +4n
+.EX
+.RB "$" " ./a.out \-s 0x100000 hola salut servus"
+Thread 1: top of stack near 0xb7d723b8; argv_string=hola
+Thread 2: top of stack near 0xb7c713b8; argv_string=salut
+Thread 3: top of stack near 0xb7b703b8; argv_string=servus
+Joined with thread 1; returned value was HOLA
+Joined with thread 2; returned value was SALUT
+Joined with thread 3; returned value was SERVUS
+.EE
+.in
+.SS Program source
+\&
+.\" SRC BEGIN (pthread_create.c)
+.EX
+#include <ctype.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+\&
+#define handle_error_en(en, msg) \e
+        do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+#define handle_error(msg) \e
+        do { perror(msg); exit(EXIT_FAILURE); } while (0)
+\&
+struct thread_info {    /* Used as argument to thread_start() */
+    pthread_t thread_id;        /* ID returned by pthread_create() */
+    int       thread_num;       /* Application\-defined thread # */
+    char     *argv_string;      /* From command\-line argument */
+};
+\&
+/* Thread start function: display address near top of our stack,
+   and return upper\-cased copy of argv_string. */
+\&
+static void *
+thread_start(void *arg)
+{
+    struct thread_info *tinfo = arg;
+    char *uargv;
+\&
+    printf("Thread %d: top of stack near %p; argv_string=%s\en",
+           tinfo\->thread_num, (void *) &tinfo, tinfo\->argv_string);
+\&
+    uargv = strdup(tinfo\->argv_string);
+    if (uargv == NULL)
+        handle_error("strdup");
+\&
+    for (char *p = uargv; *p != \[aq]\e0\[aq]; p++)
+        *p = toupper(*p);
+\&
+    return uargv;
+}
+\&
+int
+main(int argc, char *argv[])
+{
+    int                 s, opt;
+    void                *res;
+    size_t              num_threads;
+    ssize_t             stack_size;
+    pthread_attr_t      attr;
+    struct thread_info  *tinfo;
+\&
+    /* The "\-s" option specifies a stack size for our threads. */
+\&
+    stack_size = \-1;
+    while ((opt = getopt(argc, argv, "s:")) != \-1) {
+        switch (opt) {
+        case \[aq]s\[aq]:
+            stack_size = strtoul(optarg, NULL, 0);
+            break;
+\&
+        default:
+            fprintf(stderr, "Usage: %s [\-s stack\-size] arg...\en",
+                    argv[0]);
+            exit(EXIT_FAILURE);
+        }
+    }
+\&
+    num_threads = argc \- optind;
+\&
+    /* Initialize thread creation attributes. */
+\&
+    s = pthread_attr_init(&attr);
+    if (s != 0)
+        handle_error_en(s, "pthread_attr_init");
+\&
+    if (stack_size > 0) {
+        s = pthread_attr_setstacksize(&attr, stack_size);
+        if (s != 0)
+            handle_error_en(s, "pthread_attr_setstacksize");
+    }
+\&
+    /* Allocate memory for pthread_create() arguments. */
+\&
+    tinfo = calloc(num_threads, sizeof(*tinfo));
+    if (tinfo == NULL)
+        handle_error("calloc");
+\&
+    /* Create one thread for each command\-line argument. */
+\&
+    for (size_t tnum = 0; tnum < num_threads; tnum++) {
+        tinfo[tnum].thread_num = tnum + 1;
+        tinfo[tnum].argv_string = argv[optind + tnum];
+\&
+        /* The pthread_create() call stores the thread ID into
+           corresponding element of tinfo[]. */
+\&
+        s = pthread_create(&tinfo[tnum].thread_id, &attr,
+                           &thread_start, &tinfo[tnum]);
+        if (s != 0)
+            handle_error_en(s, "pthread_create");
+    }
+\&
+    /* Destroy the thread attributes object, since it is no
+       longer needed. */
+\&
+    s = pthread_attr_destroy(&attr);
+    if (s != 0)
+        handle_error_en(s, "pthread_attr_destroy");
+\&
+    /* Now join with each thread, and display its returned value. */
+\&
+    for (size_t tnum = 0; tnum < num_threads; tnum++) {
+        s = pthread_join(tinfo[tnum].thread_id, &res);
+        if (s != 0)
+            handle_error_en(s, "pthread_join");
+\&
+        printf("Joined with thread %d; returned value was %s\en",
+               tinfo[tnum].thread_num, (char *) res);
+        free(res);      /* Free memory allocated by thread */
+    }
+\&
+    free(tinfo);
+    exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.ad l
+.nh
+.BR getrlimit (2),
+.BR pthread_attr_init (3),
+.BR pthread_cancel (3),
+.BR pthread_detach (3),
+.BR pthread_equal (3),
+.BR pthread_exit (3),
+.BR pthread_getattr_np (3),
+.BR pthread_join (3),
+.BR pthread_self (3),
+.BR pthread_setattr_default_np (3),
+.BR pthreads (7)