man2/splice.2: document SPLICE_F_NOWAIT
Commit Message
Patch for SPLICE_F_NOWAIT submitted to LKML:
https://lore.kernel.org/lkml/20230926063609.2451260-1-max.kellermann@ionos.com/
In the HISTORY section, I declared Linux 6.7 as the first version to
have this feature, but this is only speculation, because
SPLICE_F_NOWAIT is still under discussion and has not yet been merged.
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
---
man2/splice.2 | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
Comments
Hi Max,
On Tue, Sep 26, 2023 at 09:04:02AM +0200, Max Kellermann wrote:
> Patch for SPLICE_F_NOWAIT submitted to LKML:
> https://lore.kernel.org/lkml/20230926063609.2451260-1-max.kellermann@ionos.com/
>
> In the HISTORY section, I declared Linux 6.7 as the first version to
> have this feature, but this is only speculation, because
> SPLICE_F_NOWAIT is still under discussion and has not yet been merged.
>
> Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Please find some formatting issues below.
Cheers,
Alex
> ---
> man2/splice.2 | 23 +++++++++++++++++++++--
> 1 file changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/man2/splice.2 b/man2/splice.2
> index e9a18e668..1e686b858 100644
> --- a/man2/splice.2
> +++ b/man2/splice.2
> @@ -89,13 +89,27 @@ call);
> in the future, a correct implementation may be restored.
> .TP
> .B SPLICE_F_NONBLOCK
> -Do not block on I/O.
> +Do not block on I/O on pipes.
> This makes the splice pipe operations nonblocking, but
> .BR splice ()
> may nevertheless block because the file descriptors that
> are spliced to/from may block (unless they have the
> .B O_NONBLOCK
> -flag set).
> +flag set or
> +.B SPLICE_F_NOWAIT
> +is specified).
> +.TP
> +.B SPLICE_F_NOWAIT
> +If no data is immediately available on
> +.I fd_in
> +and it is not a pipe, do not wait (e.g. for backing storage or locks),
> +but return immediately with
> +.B EAGAIN.
.BR EAGAIN .
> +This is analogous to the
> +.B RWF_NOWAIT
> +flag of
> +.BR preadv2()
.BR preadv2 ().
> +.
> .TP
> .B SPLICE_F_MORE
> More data will be coming in a subsequent splice.
> @@ -138,6 +152,8 @@ is set to indicate the error.
> .TP
> .B EAGAIN
> .B SPLICE_F_NONBLOCK
> +or
> +.B SPLICE_F_NOWAIT
> was specified in
> .I flags
> or one of the file descriptors had been marked as nonblocking
> @@ -192,6 +208,9 @@ was required to be a pipe.
> Since Linux 2.6.31,
> .\" commit 7c77f0b3f9208c339a4b40737bb2cb0f0319bb8d
> both arguments may refer to pipes.
> +.PP
> +.B SPLICE_F_NOWAIT
> +was added in Linux 6.7.
> .SH NOTES
> The three system calls
> .BR splice (),
> --
> 2.39.2
>
@@ -89,13 +89,27 @@ call);
in the future, a correct implementation may be restored.
.TP
.B SPLICE_F_NONBLOCK
-Do not block on I/O.
+Do not block on I/O on pipes.
This makes the splice pipe operations nonblocking, but
.BR splice ()
may nevertheless block because the file descriptors that
are spliced to/from may block (unless they have the
.B O_NONBLOCK
-flag set).
+flag set or
+.B SPLICE_F_NOWAIT
+is specified).
+.TP
+.B SPLICE_F_NOWAIT
+If no data is immediately available on
+.I fd_in
+and it is not a pipe, do not wait (e.g. for backing storage or locks),
+but return immediately with
+.B EAGAIN.
+This is analogous to the
+.B RWF_NOWAIT
+flag of
+.BR preadv2()
+.
.TP
.B SPLICE_F_MORE
More data will be coming in a subsequent splice.
@@ -138,6 +152,8 @@ is set to indicate the error.
.TP
.B EAGAIN
.B SPLICE_F_NONBLOCK
+or
+.B SPLICE_F_NOWAIT
was specified in
.I flags
or one of the file descriptors had been marked as nonblocking
@@ -192,6 +208,9 @@ was required to be a pipe.
Since Linux 2.6.31,
.\" commit 7c77f0b3f9208c339a4b40737bb2cb0f0319bb8d
both arguments may refer to pipes.
+.PP
+.B SPLICE_F_NOWAIT
+was added in Linux 6.7.
.SH NOTES
The three system calls
.BR splice (),