* Re: [PATCH] vmsplice.2: SPLICE_F_GIFT became no-op [not found] <20190801222417.14413-1-leonardo@linux.ibm.com> @ 2019-09-13 12:55 ` Michael Kerrisk (man-pages) 2019-11-14 18:56 ` Leonardo Bras 2019-12-17 21:12 ` Leonardo Bras 0 siblings, 2 replies; 5+ messages in thread From: Michael Kerrisk (man-pages) @ 2019-09-13 12:55 UTC (permalink / raw) To: Leonardo Bras, Jens Axboe; +Cc: mtk.manpages, linux-man Hello Jens, Would you be willing to take a look at this man-pages bug report relating to vmsplice()? Thanks, Michael On 8/2/19 12:24 AM, Leonardo Bras wrote: > As explained in splice.2, SPLICE_F_MOVE became a no-op, and since it > is needed to use page gifting, it made SPLICE_F_GIFT a no-op too. > > I took a look in current code, and found no use of this flag: > When enabled, it sets PIPE_BUF_FLAG_GIFT,which is only checked in > user_page_pipe_buf_steal, which is only used on > user_page_pipe_buf_ops, as a .steal component. > > But, in the whole kernel code, there is no calling of a steal() > function, making me believe this flag is not used anymore. > > Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> > --- > man2/vmsplice.2 | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/man2/vmsplice.2 b/man2/vmsplice.2 > index 17834607b..94fb86142 100644 > --- a/man2/vmsplice.2 > +++ b/man2/vmsplice.2 > @@ -123,6 +123,11 @@ if this flag is not specified, then a subsequent > .B SPLICE_F_MOVE > must copy the pages. > Data must also be properly page aligned, both in memory and length. > +Starting in Linux 2.6.21, it is a no-op, because the > +.B SPLICE_F_MOVE > +also became a no-op on > +.BR splice (2) > +. > .\" FIXME > .\" It looks like the page-alignment requirement went away with > .\" commit bd1a68b59c8e3bce45fb76632c64e1e063c3962d > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] vmsplice.2: SPLICE_F_GIFT became no-op 2019-09-13 12:55 ` [PATCH] vmsplice.2: SPLICE_F_GIFT became no-op Michael Kerrisk (man-pages) @ 2019-11-14 18:56 ` Leonardo Bras 2019-12-17 21:12 ` Leonardo Bras 1 sibling, 0 replies; 5+ messages in thread From: Leonardo Bras @ 2019-11-14 18:56 UTC (permalink / raw) To: Michael Kerrisk (man-pages), Jens Axboe; +Cc: linux-man [-- Attachment #1: Type: text/plain, Size: 1676 bytes --] On Fri, 2019-09-13 at 14:55 +0200, Michael Kerrisk (man-pages) wrote: > Hello Jens, > > Would you be willing to take a look at this man-pages bug report > relating to vmsplice()? > > Thanks, > > Michael Hello Michael, Jens, Any update about this patch? Kind Regards, > > On 8/2/19 12:24 AM, Leonardo Bras wrote: > > As explained in splice.2, SPLICE_F_MOVE became a no-op, and since > > it > > is needed to use page gifting, it made SPLICE_F_GIFT a no-op too. > > > > I took a look in current code, and found no use of this flag: > > When enabled, it sets PIPE_BUF_FLAG_GIFT,which is only checked in > > user_page_pipe_buf_steal, which is only used on > > user_page_pipe_buf_ops, as a .steal component. > > > > But, in the whole kernel code, there is no calling of a steal() > > function, making me believe this flag is not used anymore. > > > > Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> > > --- > > man2/vmsplice.2 | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/man2/vmsplice.2 b/man2/vmsplice.2 > > index 17834607b..94fb86142 100644 > > --- a/man2/vmsplice.2 > > +++ b/man2/vmsplice.2 > > @@ -123,6 +123,11 @@ if this flag is not specified, then a > > subsequent > > .B SPLICE_F_MOVE > > must copy the pages. > > Data must also be properly page aligned, both in memory and > > length. > > +Starting in Linux 2.6.21, it is a no-op, because the > > +.B SPLICE_F_MOVE > > +also became a no-op on > > +.BR splice (2) > > +. > > .\" FIXME > > .\" It looks like the page-alignment requirement went away with > > .\" commit bd1a68b59c8e3bce45fb76632c64e1e063c3962d > > > > [-- Attachment #2: This is a digitally signed message part --] [-- Type: application/pgp-signature, Size: 833 bytes --] ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] vmsplice.2: SPLICE_F_GIFT became no-op 2019-09-13 12:55 ` [PATCH] vmsplice.2: SPLICE_F_GIFT became no-op Michael Kerrisk (man-pages) 2019-11-14 18:56 ` Leonardo Bras @ 2019-12-17 21:12 ` Leonardo Bras 2019-12-18 1:13 ` Jens Axboe 1 sibling, 1 reply; 5+ messages in thread From: Leonardo Bras @ 2019-12-17 21:12 UTC (permalink / raw) To: Michael Kerrisk (man-pages), Jens Axboe; +Cc: linux-man [-- Attachment #1: Type: text/plain, Size: 1688 bytes --] On Fri, 2019-09-13 at 14:55 +0200, Michael Kerrisk (man-pages) wrote: > Hello Jens, > > Would you be willing to take a look at this man-pages bug report > relating to vmsplice()? Hello Jens, Could you please provide feedback on this patch? Thank you, Leonardo Bras > > Thanks, > > Michael > > On 8/2/19 12:24 AM, Leonardo Bras wrote: > > As explained in splice.2, SPLICE_F_MOVE became a no-op, and since it > > is needed to use page gifting, it made SPLICE_F_GIFT a no-op too. > > > > I took a look in current code, and found no use of this flag: > > When enabled, it sets PIPE_BUF_FLAG_GIFT,which is only checked in > > user_page_pipe_buf_steal, which is only used on > > user_page_pipe_buf_ops, as a .steal component. > > > > But, in the whole kernel code, there is no calling of a steal() > > function, making me believe this flag is not used anymore. > > > > Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> > > --- > > man2/vmsplice.2 | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/man2/vmsplice.2 b/man2/vmsplice.2 > > index 17834607b..94fb86142 100644 > > --- a/man2/vmsplice.2 > > +++ b/man2/vmsplice.2 > > @@ -123,6 +123,11 @@ if this flag is not specified, then a subsequent > > .B SPLICE_F_MOVE > > must copy the pages. > > Data must also be properly page aligned, both in memory and length. > > +Starting in Linux 2.6.21, it is a no-op, because the > > +.B SPLICE_F_MOVE > > +also became a no-op on > > +.BR splice (2) > > +. > > .\" FIXME > > .\" It looks like the page-alignment requirement went away with > > .\" commit bd1a68b59c8e3bce45fb76632c64e1e063c3962d > > > > [-- Attachment #2: This is a digitally signed message part --] [-- Type: application/pgp-signature, Size: 833 bytes --] ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] vmsplice.2: SPLICE_F_GIFT became no-op 2019-12-17 21:12 ` Leonardo Bras @ 2019-12-18 1:13 ` Jens Axboe 2019-12-18 16:22 ` Leonardo Bras 0 siblings, 1 reply; 5+ messages in thread From: Jens Axboe @ 2019-12-18 1:13 UTC (permalink / raw) To: Leonardo Bras, Michael Kerrisk (man-pages); +Cc: linux-man Sorry, better late than never? He's right, Nick Piggin removed that flag (and promised to reinstate it, but a decade later I'm not holding my breath). On 12/17/19 2:12 PM, Leonardo Bras wrote: > On Fri, 2019-09-13 at 14:55 +0200, Michael Kerrisk (man-pages) wrote: >> Hello Jens, >> >> Would you be willing to take a look at this man-pages bug report >> relating to vmsplice()? > > Hello Jens, > > Could you please provide feedback on this patch? > > Thank you, > Leonardo Bras > > >> >> Thanks, >> >> Michael >> >> On 8/2/19 12:24 AM, Leonardo Bras wrote: >>> As explained in splice.2, SPLICE_F_MOVE became a no-op, and since it >>> is needed to use page gifting, it made SPLICE_F_GIFT a no-op too. >>> >>> I took a look in current code, and found no use of this flag: >>> When enabled, it sets PIPE_BUF_FLAG_GIFT,which is only checked in >>> user_page_pipe_buf_steal, which is only used on >>> user_page_pipe_buf_ops, as a .steal component. >>> >>> But, in the whole kernel code, there is no calling of a steal() >>> function, making me believe this flag is not used anymore. >>> >>> Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> >>> --- >>> man2/vmsplice.2 | 5 +++++ >>> 1 file changed, 5 insertions(+) >>> >>> diff --git a/man2/vmsplice.2 b/man2/vmsplice.2 >>> index 17834607b..94fb86142 100644 >>> --- a/man2/vmsplice.2 >>> +++ b/man2/vmsplice.2 >>> @@ -123,6 +123,11 @@ if this flag is not specified, then a subsequent >>> .B SPLICE_F_MOVE >>> must copy the pages. >>> Data must also be properly page aligned, both in memory and length. >>> +Starting in Linux 2.6.21, it is a no-op, because the >>> +.B SPLICE_F_MOVE >>> +also became a no-op on >>> +.BR splice (2) >>> +. >>> .\" FIXME >>> .\" It looks like the page-alignment requirement went away with >>> .\" commit bd1a68b59c8e3bce45fb76632c64e1e063c3962d >>> >> >> -- Jens Axboe ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] vmsplice.2: SPLICE_F_GIFT became no-op 2019-12-18 1:13 ` Jens Axboe @ 2019-12-18 16:22 ` Leonardo Bras 0 siblings, 0 replies; 5+ messages in thread From: Leonardo Bras @ 2019-12-18 16:22 UTC (permalink / raw) To: Jens Axboe, Michael Kerrisk (man-pages); +Cc: linux-man [-- Attachment #1: Type: text/plain, Size: 293 bytes --] On Tue, 2019-12-17 at 18:13 -0700, Jens Axboe wrote: > Sorry, better late than never? No problem :) > He's right, Nick Piggin removed that flag (and promised to reinstate it, > but a decade later I'm not holding my breath). Thanks for the feedback! Best regards, Leonardo Bras [-- Attachment #2: This is a digitally signed message part --] [-- Type: application/pgp-signature, Size: 833 bytes --] ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-12-18 16:22 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <20190801222417.14413-1-leonardo@linux.ibm.com> 2019-09-13 12:55 ` [PATCH] vmsplice.2: SPLICE_F_GIFT became no-op Michael Kerrisk (man-pages) 2019-11-14 18:56 ` Leonardo Bras 2019-12-17 21:12 ` Leonardo Bras 2019-12-18 1:13 ` Jens Axboe 2019-12-18 16:22 ` Leonardo Bras
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