LDP
/
man-pages
mirror of https://github.com/mkerrisk/man-pages
0
1
Fork 0
Code Releases Activity

futex.2: Expand FUTEX_FD description 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2015-01-13 10:11:46 +01:00
parent 75bc6c1197
commit ff5976814d
1 changed files with 24 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
man2/futex.2
View File

@ -435,14 +435,25 @@ plus the number of waiters woken on the futex
.TP
.BR FUTEX_FD " (from Linux 2.6.0 up to and including Linux 2.6.25)"
.\" Strictly speaking, from Linux 2.5.x to 2.6.25
To support asynchronous wakeups, this operation associates a file descriptor
with a futex.
This operation creates a file descriptor that is associated with the futex at
.IR uaddr .
.\" , suitable for .BR poll (2).
If another process executes a
.BR FUTEX_WAKE ,
the process will receive the signal number that was passed in
.IR val .
The calling process must close the returned file descriptor after use.
When another process performs a
.BR FUTEX_WAKE
on the futex, the file descriptor indicates as being readable with
.BR select (2),
.BR poll (2),
and
.BR epoll (7)
The file descriptor can be used to obtain asynchronous notifications:
if
.I val
is nonzero, then when another process executes a
.BR FUTEX_WAKE ,
the caller will receive the signal number that was passed in
.IR val .
The arguments
.IR timeout ,
@ -677,10 +688,17 @@ and the kernel state; that is, it detected a waiter which waits in
on
.IR uaddr .
.TP
.BR EINVAL
.RB ( FUTEX_FD )
The signal number supplied in
.I val
is invalid.
.TP
.B EINVAL
Invalid argument.
.TP
.B ENFILE
.RB ( FUTEX_FD )
The system limit on the total number of open files has been reached.
.TP
.B ENOSYS