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[linuxjm/jm.git] / manual / LDP_man-pages / draft / man2 / futex.2

.\" Page by b.hubert - may be freely modified and distributed
.\"
.\" Niki A. Rahimi (LTC Security Development, narahimi@us.ibm.com)
.\" added ERRORS section.
.\"
.\" Modified 2004-06-17 mtk
.\" Modified 2004-10-07 aeb, added FUTEX_REQUEUE, FUTEX_CMP_REQUEUE
.\"
.\" FIXME
.\" 2.6.14 adds FUTEX_WAKE_OP
.\" 2.6.18 adds (Ingo Molnar) priority inheritance support:
.\" FUTEX_LOCK_PI, FUTEX_UNLOCK_PI, and FUTEX_TRYLOCK_PI.  These need
.\" to be documented in the manual page.  Probably there is sufficient
.\" material in the kernel source file Documentation/pi-futex.txt.
.\" 2.6.25 adds FUTEX_WAKE_BITSET, FUTEX_WAIT_BITSET
.\"
.\" Japanese Version Copyright(C) 2003 Suzuki Takashi
.\"         all rights reserved.
.\" Translated Fri Oct 24 10:37:10 JST 2003
.\"         by Suzuki Takashi.
.\" Updated & Modified Sat Feb  5 14:28:53 JST 2005
.\"         by Yuichi SATO <ysato444@yahoo.co.jp>, LDP v2.01
.\" Updated & Modified Wed Jan  3 04:51:22 JST 2007 by Yuichi SATO, LDP v2.43
.\"
.\"WORD: integer                int ·¿ÊÑ¿ô
.\"WORD: sleep                  µ¯¾²ÂÔ¤Á¤¹¤ë
.\"WORD: wake                   µ¯¾²¤¹¤ë
.\"WORD: wake up                µ¯¾²¤¹¤ë
.\"
.TH FUTEX 2 2008-11-27 "Linux" "Linux Programmer's Manual"
.\"O .SH NAME
.SH ̾Á°
.\"O futex \- Fast Userspace Locking system call
futex \- ¹â®¥æ¡¼¥¶¶õ´Ö¥í¥Ã¥¯µ¡¹½¤Î¥·¥¹¥Æ¥à¥³¡¼¥ë
.\"O .SH SYNOPSIS
.SH ½ñ¼°
.nf
.sp
.B "#include <linux/futex.h>"
.B "#include <sys/time.h>"
.sp
.BI "int futex(int *" uaddr ", int " op ", int " val \
", const struct timespec *" timeout ,
.br
.BI "          int *" uaddr2 ", int " val3 );
.\" int *? void *? u32 *?
.fi
.\"O .SH "DESCRIPTION"
.SH ÀâÌÀ
.PP
.\"O The
.\"O .BR futex ()
.\"O system call provides a method for
.\"O a program to wait for a value at a given address to change, and a
.\"O method to wake up anyone waiting on a particular address (while the
.\"O addresses for the same memory in separate processes may not be
.\"O equal, the kernel maps them internally so the same memory mapped in
.\"O different locations will correspond for
.\"O .BR futex ()
.\"O calls).
.\"O It is typically used to
.\"O implement the contended case of a lock in shared memory, as
.\"O described in
.\"O .BR futex (7).
.BR futex ()
¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï¡¢
»ØÄꤷ¤¿¥¢¥É¥ì¥¹¤ÎÃͤ¬Êѹ¹¤µ¤ì¤ë¤Î¤ò¥×¥í¥°¥é¥à¤¬ÂԤļêÃʤä
ÆÃÄê¤Î¥¢¥É¥ì¥¹¤ËÂФ·¤ÆÂÔµ¡Ãæ¤Î¥×¥í¥»¥¹¤ò wake (µ¯¾²) ¤µ¤»¤ë¼êÃʤòÄ󶡤¹¤ë
(¥×¥í¥»¥¹¤¬°Û¤Ê¤ì¤ÐƱ¤¸¥á¥â¥ê¤ËÂФ¹¤ë¥¢¥É¥ì¥¹¤âƱ¤¸¤Ç¤Ï¤Ê¤¤¤«¤â¤·¤ì¤Ê¤¤¤¬¡¢
¥«¡¼¥Í¥ë¤Ï°Û¤Ê¤ë°ÌÃ֤˥ޥåפµ¤ì¤¿Æ±¤¸¥á¥â¥ê¤ò
.BR futex ()
¤Ç»È¤¨¤ë¤è¤¦ÆâÉô¤Ç¥Þ¥Ã¥×¤¹¤ë)¡£
ŵ·¿Åª¤Ë¤Ï¡¢futex ¤Ï
.BR futex (7)
¤Ëµ­¤µ¤ì¤Æ¤¤¤ë¤è¤¦¤Ë¡¢
¶¦Í­¥á¥â¥êÃæ¤Î¥í¥Ã¥¯¤¬¶¥¹ç¤¹¤ë¾ì¹ç¤Î½èÍý¤ò¼ÂÁõ¤¹¤ë¤Î¤ËÍѤ¤¤é¤ì¤ë¡£
.PP
.\"O When a
.\"O .BR futex (7)
.\"O operation did not finish uncontended in userspace, a call needs to be made
.\"O to the kernel to arbitrate.
.\"O Arbitration can either mean putting the calling
.\"O process to sleep or, conversely, waking a waiting process.
.BR futex (7)
¤ÎÁàºî¤¬¥æ¡¼¥¶¶õ´Ö¤Ç¶¥¹ç¤Ê¤¯´°Î»¤·¤Ê¤«¤Ã¤¿¾ì¹ç¡¢
¥«¡¼¥Í¥ë¤ËÃçºÛ¤µ¤»¤ë¤¿¤á¤Ë¥·¥¹¥Æ¥à¥³¡¼¥ë¤ò¸Æ¤ÖɬÍפ¬¤¢¤ë¡£
ÃçºÛ¤È¤¤¤¦¤Î¤Ï¡¢¸Æ¤Ó½Ð¤·¥×¥í¥»¥¹¤ò sleep (µ¯¾²ÂÔ¤Á) ¤µ¤»¤¿¤ê¡¢È¿ÂФË
ÂÔ¤Á¥×¥í¥»¥¹¤ò wake ¤µ¤»¤¿¤ê¤¹¤ë¤³¤È¤ò°ÕÌ£¤¹¤ë¡£
.PP
.\"O Callers of this function are expected to adhere to the semantics as set out in
.\"O .BR futex (7).
.\"O As these
.\"O semantics involve writing nonportable assembly instructions, this in turn
.\"O probably means that most users will in fact be library authors and not
.\"O general application developers.
¤³¤Î´Ø¿ô¤ò¸Æ¤Ó½Ð¤¹¥×¥í¥»¥¹¤Ï
.BR futex (7)
¤Ëµ­½Ò¤µ¤ì¤Æ¤¤¤ë¥»¥Þ¥ó¥Æ¥£¥¯¥¹¤ËÃé¼Â¤Ç¤¢¤ë¤³¤È¤¬Í׵ᤵ¤ì¤ë¡£
¤³¤Î¥»¥Þ¥ó¥Æ¥£¥¯¥¹¤Ë¤Ï°Ü¿¢ÉÔ²Äǽ¤Ê¥¢¥»¥ó¥Ö¥êÌ¿Îá¤ò½ñ¤¯¤³¤È¤¬´Þ¤Þ¤ì¤ë¡£
¤³¤Î¤³¤È¤Ï¸À¤¤´¹¤¨¤ë¤È futex ¤Î¥æ¡¼¥¶¤Î¤Û¤È¤ó¤É¤Ï¼ÂºÝ¤Ï¥é¥¤¥Ö¥é¥ê¤Îºî¼Ô¤Ç¤¢¤ê¡¢
°ìÈÌ¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤Î³«È¯¼Ô¤Ç¤Ï¤Ê¤¤¤È¤¤¤¦¤³¤È¤Ç¤¢¤ë¡£
.PP
.\"O The
.\"O .I uaddr
.\"O argument needs to point to an aligned integer which stores the counter.
.\"O The operation to execute is passed via the
.\"O .I op
.\"O argument, along with a value
.\"O .IR val .
.I uaddr
°ú¤­¿ô¤Ï¡¢¥«¥¦¥ó¥¿¤ò³ÊǼ¤¹¤ë¡¢
¥¢¥é¥¤¥ó¥á¥ó¥È¤Î·¤Ã¤¿ int ·¿ÊÑ¿ô¤ò»Ø¤·¤Æ¤¤¤ëɬÍפ¬¤¢¤ë¡£
¼Â¹Ô¤¹¤ëÁàºî¤Ï
.I op
°ú¤­¿ô¤ò²ð¤·¤Æ¡¢ÃÍ
.I val
¤È¤È¤â¤ËÅϤµ¤ì¤ë¡£
.PP
.\"O Five operations are currently defined:
¸½ºß¤Î¤È¤³¤í 5 ¤Ä¤ÎÁàºî¤¬ÄêµÁ¤µ¤ì¤Æ¤¤¤ë:
.TP
.B FUTEX_WAIT
.\"O This operation atomically verifies that the futex address
.\"O .I uaddr
.\"O still contains the value
.\"O .IR val ,
.\"O and sleeps awaiting
.\"O .B FUTEX_WAKE
.\"O on this futex address.
.\"O If the
.\"O .I timeout
.\"O argument is non-NULL, its contents describe the maximum
.\"O duration of the wait, which is infinite otherwise.
.\"O The arguments
.\"O .I uaddr2
.\"O and
.\"O .I val3
.\"O are ignored.
¤³¤ÎÁàºî¤Ï futex ¥¢¥É¥ì¥¹
.I uaddr
¤Ë»ØÄꤵ¤ì¤¿ÃÍ
.I val
¤¬¤Þ¤À³ÊǼ¤µ¤ì¤Æ¤¤¤ë¤«¤É¤¦¤«¤òÉÔ²ÄʬÁàºî¤Ç¸¡¾Ú¤·¡¢
sleep ¾õÂÖ¤Ç
¤³¤Î futex ¥¢¥É¥ì¥¹¤ËÂФ·¤Æ
.B FUTEX_WAKE
¤¬¼Â¹Ô¤µ¤ì¤ë¤Î¤òÂԤġ£
.I timeout
°ú¤­¿ô¤¬ NULL ¤Ç¤Ê¤¤¾ì¹ç¡¢¤½¤ÎÆâÍƤÏ
ÂÔ¤Á»þ´Ö¤ÎºÇÂçÃͤòɽ¤¹¡£NULL ¤Î¾ì¹ç¤Ï̵¸ÂÂç¤òɽ¤¹¡£
°ú¤­¿ô
.I uaddr2
¤È
.I val3
¤Ï̵»ë¤µ¤ì¤ë¡£

.\"O For
.\"O .BR futex (7),
.\"O this call is executed if decrementing the count gave a negative value
.\"O (indicating contention), and will sleep until another process releases
.\"O the futex and executes the
.\"O .B FUTEX_WAKE
.\"O operation.
.BR futex (7)
¤Ë¾È¤é¤·¹ç¤ï¤»¤ë¤È¡¢¤³¤Î¸Æ¤Ó½Ð¤·¤Ï
¥«¥¦¥ó¥È¤Î¥Ç¥¯¥ê¥á¥ó¥È¤ÇÉé¤ÎÃÍ (¶¥¹ç¤òɽ¤¹) ¤Ë¤Ê¤Ã¤¿¾ì¹ç¤Ë¼Â¹Ô¤µ¤ì¡¢
ÊÌ¤Î¥×¥í¥»¥¹¤¬¤½¤Î futex ¤ò²òÊü¤·
.B FUTEX_WAKE
¤ÎÁàºî¤ò¼Â¹Ô¤¹¤ë¤Þ¤Ç sleep ¤¹¤ë¡£
.TP
.B FUTEX_WAKE
.\"O This operation wakes at most \fIval\fP
.\"O processes waiting on this futex address (i.e., inside
.\"O .BR FUTEX_WAIT ).
¤³¤ÎÁàºî¤Ç¤Ï»ØÄꤷ¤¿ futex ¥¢¥É¥ì¥¹¤ËÂФ·¤ÆÂÔ¤Á¾õÂÖ¤Î
(¤¹¤Ê¤ï¤Á
.B FUTEX_WAIT
Ãæ¤Î) ºÇÂç \fIval\fP ¸Ä¤Î¥×¥í¥»¥¹¤ò wake ¤µ¤»¤ë¡£
.\"O The arguments
.\"O .IR timeout ,
.\"O .I uaddr2
.\"O and
.\"O .I val3
.\"O are ignored.
°ú¤­¿ô
.IR timeout ,
.IR uaddr2 ,
.I val3
¤Ï̵»ë¤µ¤ì¤ë¡£

.\"O For
.\"O .BR futex (7),
.\"O this is executed if incrementing
.\"O the count showed that there were waiters, once the futex value has been set
.\"O to 1 (indicating that it is available).
\fBfutex\fR(4) ¤Ë¾È¤é¤·¹ç¤ï¤»¤ë¤È¡¢
¤³¤ÎÁàºî¤Ï
¥«¥¦¥ó¥È¤Î¥¤¥ó¥¯¥ê¥á¥ó¥È¤ÇÂÔ¤Á¥×¥í¥»¥¹¤¬¤¢¤ë¤ÈȽÌÀ¤·¡¢
futex Ãͤ¬ 1 ¤ËÀßÄꤵ¤ì¤¿ (ÍøÍѲÄǽ¤Ç¤¢¤ë¤³¤È¤òɽ¤¹) ¾ì¹ç¤Ë¼Â¹Ô¤µ¤ì¤ë¡£
.TP
.\"O .BR FUTEX_FD " (present up to and including Linux 2.6.25)"
.BR FUTEX_FD " (Linux 2.6.25 °ÊÁ°)"
.\"O To support asynchronous wakeups, this operation associates a file descriptor
.\"O with a futex.
.\"O .\" , suitable for .BR poll (2).
.\"O If another process executes a
.\"O .BR FUTEX_WAKE ,
.\"O the process will receive the signal number that was passed in
.\"O number that was passed in
.\"O .IR val .
.\"O The calling process must close the returned file descriptor after use.
ÈóƱ´ü¤Î wake ¤ËÂбþ¤¹¤ë¤¿¤á¡¢¤³¤ÎÁàºî¤Ï¥Õ¥¡¥¤¥ë¥Ç¥£¥¹¥¯¥ê¥×¥¿¤ò futex ¤Ë
´ØÏ¢¤Å¤±¤ë¡£
.\" .BR poll (2)
.\" ¤ËŬ¤·¤Æ¤¤¤ë¡£
ÊÌ¤Î¥×¥í¥»¥¹¤¬
.B FUTEX_WAKE
¤ò¼Â¹Ô¤¹¤ë¤È¡¢¥×¥í¥»¥¹¤Ï
.I val
¤ÇÅϤµ¤ì¤¿¥·¥°¥Ê¥ëÈÖ¹æ¤Î¥·¥°¥Ê¥ë¤ò¼õ¿®¤¹¤ë¡£
¸Æ¤Ó½Ð¤·¥×¥í¥»¥¹¤Ï»ÈÍѸ塢ÊÖ¤µ¤ì¤¿¥Õ¥¡¥¤¥ë¥Ç¥£¥¹¥¯¥ê¥×¥¿¤ò
¥¯¥í¡¼¥º¤·¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£
.\"O The arguments
.\"O .IR timeout ,
.\"O .I uaddr2
.\"O and
.\"O .I val3
.\"O are ignored.
°ú¤­¿ô
.IR timeout ,
.IR uaddr2 ,
.I val3
¤Ï̵»ë¤µ¤ì¤ë¡£

.\"O To prevent race conditions, the caller should test if the futex has
.\"O been upped after
.\"O .B FUTEX_FD
.\"O returns.
¶¥¹ç¾õÂÖ¤òËɻߤ¹¤ë¤¿¤á¡¢¸Æ¤Ó½Ð¤·¥×¥í¥»¥¹¤Ï
.B FUTEX_FD
¤¬Ê֤俤¢¤È
futex ¤¬ up ¤µ¤ì¤¿¤«¤É¤¦¤«¤ò³Îǧ¤·¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£

.\" FIXME . Check that this flag does eventually get removed.
.\"O Because it was inherently racy,
.\"O .B FUTEX_FD
.\"O has been removed from Linux 2.6.26 onwards.
.B FUTEX_FD
¤Ï¤â¤È¤â¤È¶¥¹ç¤¬µ¯¤­¤ä¤¹¤«¤Ã¤¿¤¿¤á¡¢
Linux 2.6.26 °Ê¹ß¤Çºï½ü¤µ¤ì¤Æ¤¤¤ë¡£
.TP
.\"O .BR FUTEX_REQUEUE " (since Linux 2.5.70)"
.BR FUTEX_REQUEUE " (Linux 2.5.70 °Ê¹ß)"
.\"O This operation was introduced in order to avoid a "thundering herd" effect
.\"O when
.\"O .B FUTEX_WAKE
.\"O is used and all processes woken up need to acquire another
.\"O futex.
.\"O This call wakes up
.\"O .I val
.\"O processes, and requeues all other waiters on the futex at address
.\"O .IR uaddr2 .
¤³¤ÎÁàºî¤Ï¡¢
.B FUTEX_WAKE
¤¬»È¤ï¤ì¤Æ¤¤¤Æ¡¢¤«¤Ä wake ¤µ¤ì¤Æ¤¤¤ëÁ´¤Æ¤Î¥×¥í¥»¥¹¤¬
¾¤Î futex ¤ò¼èÆÀ¤¹¤ëɬÍפ¬¤¢¤ë¾ì¹ç¤Ë¡¢
¡Ö½Ã¤Î·²¤ì¤Î˽Áö (thundering herd)¡×¸ú²Ì¤òÈò¤±¤ë¤¿¤á¤ËƳÆþ¤µ¤ì¤¿¡£
¤³¤Î¸Æ¤Ó½Ð¤·¤Ï
.I val
¸Ä¤Î¥×¥í¥»¥¹¤ò wake ¤·¡¢¥¢¥É¥ì¥¹
.I uaddr2
¤Ç futex ¤òÂԤäƤ¤¤ë¾¤ÎÁ´¤Æ¤Î¥×¥í¥»¥¹¤òºÆÅÙ¥­¥å¡¼¤Ë¤¤¤ì¤ë¡£
.\"O The arguments
.\"O .I timeout
.\"O and
.\"O .I val3
.\"O are ignored.
°ú¤­¿ô
.I timeout
¤È
.I val3
¤Ï̵»ë¤µ¤ì¤ë¡£
.TP
.\"O .BR FUTEX_CMP_REQUEUE " (since Linux 2.6.7)"
.BR FUTEX_CMP_REQUEUE " (Linux 2.6.7 °Ê¹ß)"
.\"O There was a race in the intended use of
.\"O .BR FUTEX_REQUEUE ,
.\"O so
.\"O .B FUTEX_CMP_REQUEUE
.\"O was introduced.
.\"O This is similar to
.\"O .BR FUTEX_REQUEUE ,
.\"O but first checks whether the location
.\"O .I uaddr
.\"O still contains the value
.\"O .IR val3 .
.\"Osato:
.\"Osato: intended ¤¬¤è¤¯Ê¬¤«¤é¤Ê¤¤¡£
.\"Osato:
¸Î°Õ¤Ë
.B FUTEX_REQUEUE
¤ò»È¤¦¾ì¹ç¤Ë¶¥¹ç¤¬µ¯¤³¤ë¤¿¤á¡¢
.B FUTEX_CMP_REQUEUE
¤¬Æ³Æþ¤µ¤ì¤¿¡£¤³¤ì¤Ï
.B FUTEX_REQUEUE
¤È»÷¤Æ¤¤¤ë¤¬¡¢¾ì½ê
.I uaddr
¤ËÃÍ
.I val3
¤¬¤Þ¤ÀÊÝ»ý¤µ¤ì¤Æ¤¤¤ë¤«¤òºÇ½é¤Ë¥Á¥§¥Ã¥¯¤¹¤ë¡£
.\"O If not, the operation fails with the error
.\"O .BR EAGAIN .
.\"O The argument
.\"O .I timeout
.\"O is ignored.
ÊÝ»ý¤µ¤ì¤Æ¤¤¤Ê¤¤¾ì¹ç¡¢Áàºî¤Ï¥¨¥é¡¼
.B EAGAIN
¤Ç¼ºÇÔ¤¹¤ë¡£°ú¤­¿ô
.I timeout
¤Ï̵»ë¤µ¤ì¤ë¡£
.\"O .SH "RETURN VALUE"
.SH ÊÖ¤êÃÍ
.PP
.\"O Depending on which operation was executed,
.\"O the returned value for a successful call can have differing meanings.
¤É¤ÎÁàºî¤¬¼Â¹Ô¤µ¤ì¤¿¤«¤Ë¤è¤Ã¤Æ¡¢
À®¸ù»þ¤ÎÊÖ¤êÃͤΰÕÌ£¤¬ÊѤï¤ë¡£
.TP
.B FUTEX_WAIT
.\"O Returns 0 if the process was woken by a
.\"O .B FUTEX_WAKE
.\"O call.
.\"O In case of timeout,
.\"O the operation fails with the error
.\"O .BR ETIMEDOUT .
.\"O If the futex was not equal to the expected value,
.\"O the operation fails with the error
.\"O .BR EWOULDBLOCK .
.\"O Signals (see
.\"O .BR signal (7))
.\"O or other spurious wakeups cause
.\"O .B FUTEX_WAIT
.\"O to fail with the error
.\"O .BR EINTR .
¥×¥í¥»¥¹¤¬
.B FUTEX_WAKE
¤Î¸Æ¤Ó½Ð¤·¤Ç wake ¤¹¤ë¤È 0 ¤òÊÖ¤¹¡£
¥¿¥¤¥à¥¢¥¦¥È¤Î¾ì¹ç¡¢Áàºî¤Ï¥¨¥é¡¼
.B ETIMEOUT
¤Ç¼ºÇÔ¤¹¤ë¡£
futex ¤¬»ØÄꤵ¤ì¤¿ÃͤÈÅù¤·¤¯¤Ê¤¤¾ì¹ç¡¢
¥¨¥é¡¼
.B EWOULDBLOCK
¤Ç¼ºÇÔ¤¹¤ë¡£
¥·¥°¥Ê¥ë¤ò¼õ¿®¤¹¤ë¤«
.RB ( signal (7)
»²¾È) ¾¤Îµ¶¤Î wake ¤¬¤¢¤Ã¤¿¾ì¹ç¤Ë¤Ï¡¢¥¨¥é¡¼
.B EINTR
¤Ç¼ºÇÔ¤¹¤ë¡£
.TP
.B FUTEX_WAKE
.\"O Returns the number of processes woken up.
wake ¤·¤¿¥×¥í¥»¥¹¤Î¿ô¤òÊÖ¤¹¡£
.TP
.B FUTEX_FD
.\"O Returns the new file descriptor associated with the futex.
futex ¤Ë´ØÏ¢¤Å¤±¤é¤ì¤¿¿·¤¿¤Ê¥Õ¥¡¥¤¥ë¥Ç¥£¥¹¥¯¥ê¥×¥¿¤òÊÖ¤¹¡£
.TP
.B FUTEX_REQUEUE
.\"O Returns the number of processes woken up.
wake ¤·¤¿¥×¥í¥»¥¹¤Î¿ô¤òÊÖ¤¹¡£
.TP
.B FUTEX_CMP_REQUEUE
.\"O Returns the number of processes woken up.
wake ¤·¤¿¥×¥í¥»¥¹¤Î¿ô¤òÊÖ¤¹¡£
.PP
.\"O In the event of an error, all operations return \-1, and set
.\"O .I errno
.\"O to indicate the error.
¥¨¥é¡¼¤Î¾ì¹ç¡¢Á´¤Æ¤ÎÁàºî¤Ç \-1 ¤¬Ê֤ꡢ
.I errno
¤¬¥¨¥é¡¼¤ÎÆâÍƤò¼¨¤¹ÃͤËÀßÄꤵ¤ì¤ë¡£
.\"O .SH ERRORS
.SH ¥¨¥é¡¼
.TP
.B EACCES
.\"O No read access to futex memory.
futex ¥á¥â¥ê¤ËÆɤ߹þ¤ß¥¢¥¯¥»¥¹¸¢¤¬¤Ê¤«¤Ã¤¿¡£
.TP
.B EAGAIN
.\"O .B FUTEX_CMP_REQUEUE
.\"O found an unexpected futex value.
.\"O (This probably indicates a race;
.\"O use the safe
.\"O .B FUTEX_WAKE
.\"O now.)
.B FUTEX_CMP_REQUEUE
¤Çͽ´ü¤·¤Ê¤¤ futex Ãͤ¬¸«¤Ä¤«¤Ã¤¿
(¤³¤ì¤Ï¶¥¹ç¤ò¼¨¤·¤Æ¤¤¤ë¤«¤â¤·¤ì¤Ê¤¤¡£
¤³¤Î¾ì¹ç¤Ï°ÂÁ´¤Ê
.B FUTEX_WAKE
¤ò»È¤¦¤³¤È)¡£
.TP
.B EFAULT
.\"O Error in getting
.\"O .I timeout
.\"O information from userspace.
¥æ¡¼¥¶¶õ´Ö¤«¤é
.I timeout
¤Î¾ðÊó¤ò¼èÆÀ¤¹¤ëºÝ¤Ë¥¨¥é¡¼¤¬È¯À¸¤·¤¿¡£
.TP
.B EINVAL
.\"O An operation was not defined or error in page alignment.
Áàºî¤¬ÄêµÁ¤µ¤ì¤Æ¤¤¤Ê¤¤¡£¤Þ¤¿¤Ï¥Ú¡¼¥¸¡¦¥¢¥é¥¤¥ó¥á¥ó¥È¤Ç¥¨¥é¡¼¤¬È¯À¸¤·¤¿¡£
.TP
.B ENFILE
.\"O The system limit on the total number of open files has been reached.
¥ª¡¼¥×¥ó¤µ¤ì¤Æ¤¤¤ë¥Õ¥¡¥¤¥ë¤ÎÁí¿ô¤¬¥·¥¹¥Æ¥à¤ÎÀ©¸Â¤Ë㤷¤¿¡£
.TP
.B ENOSYS
.\"O Invalid operation specified in
.\"O .IR op .
.I op
¤Ë̵¸ú¤ÊÁàºî¤¬»ØÄꤵ¤ì¤¿¡£
.\"O .SH "VERSIONS"
.SH ¥Ð¡¼¥¸¥ç¥ó
.PP
.\"O Initial futex support was merged in Linux 2.5.7 but with different semantics
.\"O from what was described above.
.\"O A 4-argument system call with the semantics
.\"O given here was introduced in Linux 2.5.40.
.\"O In Linux 2.5.70 one argument
.\"O was added.
.\"O In Linux 2.6.7 a sixth argument was added \(em messy, especially
.\"O on the s390 architecture.
ºÇ½é¤Î futex Âбþ¤Ï Linux 2.5.7 ¤ÇÁȤ߹þ¤Þ¤ì¤¿¤¬¡¢
¾åµ­¤Î¥»¥Þ¥ó¥Æ¥£¥¯¥¹¤È¤Ï°Û¤Ê¤ë¡£
¤³¤³¤Ç¼¨¤µ¤ì¤Æ¤¤¤ë¥»¥Þ¥ó¥Æ¥£¥¯¥¹¤ò»ý¤Ä
4 ¤Ä¤Î°ú¤­¿ô¤Î¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï¡¢Linux 2.5.40 ¤ÇƳÆþ¤µ¤ì¤¿¡£
Linux 2.5.70 ¤Ç¤Ï 1 ¤Ä¤Î°ú¤­¿ô¤¬Äɲ䵤줿¡£
Linux 2.6.7 ¤Ç¤Ï 6 ÈÖÌܤΰú¤­¿ô¤¬Äɲ䵤줿¡£
¤³¤ì¤Ï±ø¤¯¡¢s390 ¥¢¡¼¥­¥Æ¥¯¥Á¥ã¾å¤ÎÆÃÊ̤Τâ¤Î¤Ç¤¢¤ë¡£
.\"O .SH "CONFORMING TO"
.SH ½àµò
.\"O This system call is Linux-specific.
¤³¤Î¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï Linux Æȼ«¤Ç¤¢¤ë¡£
.\"O .SH "NOTES"
.SH Ãí°Õ
.PP
.\"O To reiterate, bare futexes are not intended as an easy-to-use abstraction
.\"O for end-users.
.\"O (There is no wrapper function for this system call in glibc.)
.\"O Implementors are expected to be assembly literate and to have
.\"O read the sources of the futex userspace library referenced below.
·«¤êÊÖ¤¹¤¬¡¢Íç¤Î futex ¤Ï¥¨¥ó¥É¥æ¡¼¥¶¤¬Íưפ˻Ȥ¦¤³¤È¤Î¤Ç¤­¤ë³µÇ°¤È¤·¤Æ
°Õ¿Þ¤µ¤ì¤¿¤â¤Î¤Ç¤Ï¤Ê¤¤
(glibc ¤Ë¤Ï¤³¤Î¥·¥¹¥Æ¥à¥³¡¼¥ë¤ËÂФ¹¤ë¥é¥Ã¥Ñ¡¼´Ø¿ô¤Ï¤Ê¤¤)¡£
¼ÂÁõ¼Ô¤Ï¡¢¥¢¥»¥ó¥Ö¥ê¸À¸ì¤Ë´·¤ì¤Æ¤ª¤ê¡¢°Ê²¼¤Ëµó¤²¤ë futex ¥æ¡¼¥¶¶õ´Ö¥é¥¤¥Ö¥é¥ê¤Î
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.\"O .\" .SH "AUTHORS"
.\" .SH Ãø¼Ô
.\" .PP
.\"O .\" Futexes were designed and worked on by
.\"O .\" Hubertus Franke (IBM Thomas J. Watson Research Center),
.\"O .\" Matthew Kirkwood, Ingo Molnar (Red Hat)
.\"O .\" and Rusty Russell (IBM Linux Technology Center).
.\"O .\" This page written by bert hubert.
.\" futex ¤Ï Hubertus Franke (IBM Thomas J. Watson Research Center),
.\" Matthew Kirkwood, Ingo Molnar (Red Hat),
.\" Rusty Russell (IBM Linux Technology Center) ¤¬À߷פ·¡¢ºîÀ®¤·¤¿¡£
.\" ¤³¤Î¥Ú¡¼¥¸¤Ï bert hubert ¤¬µ­¤·¤¿¡£
.\"O .SH SEE ALSO
.SH ´ØÏ¢¹àÌÜ
.BR futex (7)
.PP
\fIFuss, Futexes and Furwocks: Fast Userlevel Locking in Linux\fP
(proceedings of the Ottawa Linux Symposium 2002),
.\"O futex example library, futex-*.tar.bz2
futex ¤Î»ÈÍÑÎã¥é¥¤¥Ö¥é¥ê, futex-*.tar.bz2
<URL:ftp://ftp.nl.kernel.org/pub/linux/kernel/people/rusty/>.