From: "Michael S. Tsirkin" <mst@redhat.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Miller <davem@davemloft.net>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 08/17] {macvtap,tun}_get_user(): switch to iov_iter
Date: Tue, 3 Feb 2015 16:19:25 +0100 [thread overview]
Message-ID: <20150203151925.GA9031@redhat.com> (raw)
In-Reply-To: <20150203142728.GC29656@ZenIV.linux.org.uk>
On Tue, Feb 03, 2015 at 02:27:28PM +0000, Al Viro wrote:
> On Tue, Feb 03, 2015 at 12:10:44PM +0200, Michael S. Tsirkin wrote:
>
> > Hmm does copy_from_iter actually modify the iovec?
> > If so, won't this break aio on tun/macvtap, by
> > reversing the effect of
> > commit 6f26c9a7555e5bcca3560919db9b852015077dae
> > tun: fix tun_chr_aio_write so that aio works
> > ?
> >
> >
> > Maybe we should change iovec_iter to avoid modifying the
> > underlying iovec?
>
> iov_iter never changes the underlying iovec (or kvec, or bvec).
> iter->iov_offset changes as you go and once you have consumed an
> entire iovec element ->iov is incremented to point to the next one
> (and ->iov_offset is reset to 0 at that point). *Contents* of
> iter->iov is never modified.
I see, I think I misread the code.
Thanks for the clarification.
--
MST
next prev parent reply other threads:[~2015-02-03 15:19 UTC|newest]
Thread overview: 133+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-18 8:47 [RFC] situation with csum_and_copy_... API Al Viro
2014-11-18 19:40 ` [patches][RFC] " Al Viro
2014-11-18 19:41 ` [PATCH 1/5] separate kernel- and userland-side msghdr Al Viro
2014-11-18 19:42 ` [PATCH 2/5] {compat_,}verify_iovec(): switch to generic copying of iovecs Al Viro
2014-11-18 19:42 ` [PATCH 3/5] remove a bunch of now-pointless access_ok() in net Al Viro
2014-11-18 19:43 ` [PATCH 4/5] bury skb_copy_to_page() Al Viro
2014-11-18 19:43 ` [PATCH 5/5] fold verify_iovec() into copy_msghdr_from_user() Al Viro
2014-11-19 20:25 ` [patches][RFC] situation with csum_and_copy_... API David Miller
2014-11-18 20:49 ` [RFC] " Linus Torvalds
2014-11-18 21:23 ` Al Viro
2014-11-18 21:39 ` Linus Torvalds
2014-11-19 20:31 ` David Miller
2014-11-19 20:40 ` Linus Torvalds
2014-11-19 21:17 ` Al Viro
2014-11-19 21:17 ` David Miller
2014-11-19 21:30 ` Al Viro
2014-11-19 21:53 ` David Miller
2014-11-20 21:47 ` Al Viro
2014-11-20 21:55 ` Eric Dumazet
2014-11-20 22:25 ` Al Viro
2014-11-20 22:53 ` Eric Dumazet
2014-11-21 8:49 ` Al Viro
2014-11-21 15:01 ` Eric Dumazet
2014-11-21 17:42 ` David Laight
2014-11-21 19:39 ` Al Viro
2014-11-21 19:40 ` Linus Torvalds
2014-11-24 10:03 ` David Laight
2014-11-22 3:27 ` Al Viro
2014-11-22 3:36 ` Al Viro
2014-11-24 10:27 ` David Laight
2014-11-20 23:23 ` David Miller
2014-11-21 17:26 ` David Miller
2014-11-22 4:28 ` Al Viro
2014-11-22 4:29 ` [PATCH 01/17] new helper: skb_copy_and_csum_datagram_msg() Al Viro
2014-11-22 4:30 ` [PATCH 02/17] new helper: memcpy_from_msg() Al Viro
2014-11-22 4:30 ` [PATCH 03/17] switch ipxrtr_route_packet() from iovec to msghdr Al Viro
2014-11-22 4:31 ` [PATCH 04/17] new helper: memcpy_to_msg() Al Viro
2014-11-22 4:32 ` [PATCH 05/17] switch drivers/net/tun.c to ->read_iter() Al Viro
2014-11-22 4:32 ` [PATCH 06/17] switch macvtap " Al Viro
2014-11-23 23:29 ` Ben Hutchings
2014-11-22 4:33 ` [PATCH 07/17] new helpers: skb_copy_datagram_from_iter() and zerocopy_sg_from_iter() Al Viro
2014-11-24 0:02 ` Ben Hutchings
2014-11-24 0:29 ` Ben Hutchings
2014-11-24 5:34 ` Jason Wang
2014-11-24 10:03 ` Al Viro
2014-11-22 4:33 ` [PATCH 08/17] {macvtap,tun}_get_user(): switch to iov_iter Al Viro
2014-11-24 0:27 ` Ben Hutchings
2014-11-24 1:06 ` Ben Hutchings
2014-11-24 10:15 ` Al Viro
2014-11-22 4:34 ` [PATCH 09/17] kill zerocopy_sg_from_iovec() Al Viro
2014-11-22 4:35 ` [PATCH 10/17] switch AF_PACKET and AF_UNIX to skb_copy_datagram_from_iter() Al Viro
2014-11-22 4:36 ` PATCH 11/17] switch sctp_user_addto_chunk() and sctp_datamsg_from_user() to passing iov_iter Al Viro
2014-11-22 4:36 ` [PATCH 12/17] tipc_sendmsg(): pass msghdr instead of its ->msg_iov Al Viro
2014-11-22 4:37 ` [PATCH 13/17] tipc_msg_build(): " Al Viro
2014-11-22 4:37 ` [PATCH 14/17] vmci_transport: switch ->enqeue_dgram, ->enqueue_stream and ->dequeue_stream to msghdr Al Viro
2014-11-22 4:38 ` [PATCH 15/17] [atm] switch vcc_sendmsg() to copy_from_iter() Al Viro
2014-11-22 4:38 ` [PATCH 16/17] rds: switch ->inc_copy_to_user() to passing iov_iter Al Viro
2014-11-22 4:39 ` [PATCH 17/17] rds: switch rds_message_copy_from_user() to iov_iter Al Viro
2014-11-24 2:00 ` Ben Hutchings
2014-11-24 10:17 ` Al Viro
2014-11-22 7:24 ` [RFC] situation with csum_and_copy_... API David Miller
2014-11-25 2:40 ` Al Viro
2014-11-25 14:02 ` [PATCH v2 01/17] new helper: skb_copy_and_csum_datagram_msg() Al Viro
2014-11-25 19:28 ` David Miller
2014-11-25 20:59 ` Al Viro
2014-11-26 17:27 ` David Miller
2014-12-05 5:56 ` the next chunk of iov_iter-net stuff for review Al Viro
2014-12-05 5:58 ` [PATCH 01/12] raw.c: stick msghdr into raw_frag_vec Al Viro
2014-12-05 5:58 ` [PATCH 02/12] ipv6 equivalent of "ipv4: Avoid reading user iov twice after raw_probe_proto_opt" Al Viro
2014-12-05 5:58 ` [PATCH 03/12] ip_generic_getfrag, udplite_getfrag: switch to passing msghdr Al Viro
2014-12-05 5:58 ` [PATCH 04/12] switch tcp_sock->ucopy from iovec (ucopy.iov) to msghdr (ucopy.msg) Al Viro
2014-12-05 5:58 ` [PATCH 05/12] switch l2cap ->memcpy_fromiovec() to msghdr Al Viro
2014-12-05 5:58 ` [PATCH 06/12] vmci: propagate msghdr all way down to __qp_memcpy_from_queue() Al Viro
2014-12-05 5:58 ` [PATCH 07/12] put iov_iter into msghdr Al Viro
2014-12-05 5:58 ` [PATCH 08/12] first fruits - kill l2cap ->memcpy_fromiovec() Al Viro
2014-12-05 5:58 ` [PATCH 09/12] switch memcpy_to_msg() and skb_copy{,_and_csum}_datagram_msg() to primitives Al Viro
2014-12-05 5:58 ` [PATCH 10/12] ppp_read(): switch to skb_copy_datagram_iter() Al Viro
2014-12-05 5:58 ` [PATCH 11/12] skb_copy_datagram_iovec() can die Al Viro
2014-12-05 5:58 ` [PATCH 12/12] bury memcpy_toiovec() Al Viro
2014-12-09 20:07 ` the next chunk of iov_iter-net stuff for review David Miller
2014-12-09 21:04 ` Al Viro
2014-12-09 21:17 ` David Miller
2014-12-09 21:23 ` Al Viro
2014-12-09 21:37 ` David Miller
2014-12-09 22:49 ` Al Viro
2014-12-09 22:50 ` [PATCH 01/25] iov_iter.c: macros for iterating over iov_iter Al Viro
2014-12-09 22:50 ` [PATCH 02/25] iov_iter.c: iterate_and_advance Al Viro
2014-12-09 22:50 ` [PATCH 03/25] iov_iter.c: convert iov_iter_npages() to iterate_all_kinds Al Viro
2014-12-09 22:50 ` [PATCH 04/25] iov_iter.c: convert iov_iter_get_pages() " Al Viro
2014-12-09 22:50 ` [PATCH 05/25] iov_iter.c: convert iov_iter_get_pages_alloc() " Al Viro
2014-12-09 22:50 ` [PATCH 06/25] iov_iter.c: convert iov_iter_zero() to iterate_and_advance Al Viro
2014-12-09 22:50 ` [PATCH 07/25] iov_iter.c: get rid of bvec_copy_page_{to,from}_iter() Al Viro
2014-12-09 22:50 ` [PATCH 08/25] iov_iter.c: convert copy_from_iter() to iterate_and_advance Al Viro
2014-12-09 22:50 ` [PATCH 09/25] iov_iter.c: convert copy_to_iter() " Al Viro
2014-12-09 22:50 ` [PATCH 10/25] iov_iter.c: handle ITER_KVEC directly Al Viro
2014-12-09 22:50 ` [PATCH 11/25] csum_and_copy_..._iter() Al Viro
2014-12-09 22:50 ` [PATCH 12/25] new helper: iov_iter_kvec() Al Viro
2014-12-09 22:50 ` [PATCH 13/25] copy_from_iter_nocache() Al Viro
2014-12-09 22:50 ` [PATCH 14/25] raw.c: stick msghdr into raw_frag_vec Al Viro
2014-12-09 22:50 ` [PATCH 15/25] ipv6 equivalent of "ipv4: Avoid reading user iov twice after raw_probe_proto_opt" Al Viro
2014-12-09 22:50 ` [PATCH 16/25] ip_generic_getfrag, udplite_getfrag: switch to passing msghdr Al Viro
2014-12-09 22:50 ` [PATCH 17/25] switch tcp_sock->ucopy from iovec (ucopy.iov) to msghdr (ucopy.msg) Al Viro
2014-12-09 22:50 ` [PATCH 18/25] switch l2cap ->memcpy_fromiovec() to msghdr Al Viro
2014-12-09 22:50 ` [PATCH 19/25] vmci: propagate msghdr all way down to __qp_memcpy_from_queue() Al Viro
2014-12-09 22:50 ` [PATCH 20/25] put iov_iter into msghdr Al Viro
2014-12-09 22:50 ` [PATCH 21/25] first fruits - kill l2cap ->memcpy_fromiovec() Al Viro
2014-12-09 22:50 ` [PATCH 22/25] switch memcpy_to_msg() and skb_copy{,_and_csum}_datagram_msg() to primitives Al Viro
2014-12-09 22:50 ` [PATCH 23/25] ppp_read(): switch to skb_copy_datagram_iter() Al Viro
2014-12-09 22:50 ` [PATCH 24/25] skb_copy_datagram_iovec() can die Al Viro
2014-12-09 22:50 ` [PATCH 25/25] bury memcpy_toiovec() Al Viro
2014-12-09 23:13 ` the next chunk of iov_iter-net stuff for review Al Viro
2014-12-10 18:25 ` David Miller
2014-11-25 14:02 ` [PATCH v2 02/17] new helper: memcpy_from_msg() Al Viro
2014-11-25 14:02 ` [PATCH v2 03/17] switch ipxrtr_route_packet() from iovec to msghdr Al Viro
2014-11-25 14:02 ` [PATCH v2 04/17] new helper: memcpy_to_msg() Al Viro
2014-11-25 14:02 ` [PATCH v2 05/17] switch drivers/net/tun.c to ->read_iter() Al Viro
2014-11-25 14:02 ` [PATCH v2 06/17] switch macvtap " Al Viro
2014-11-25 14:02 ` [PATCH v2 07/17] new helpers: skb_copy_datagram_from_iter() and zerocopy_sg_from_iter() Al Viro
2014-11-25 14:02 ` [PATCH v2 08/17] {macvtap,tun}_get_user(): switch to iov_iter Al Viro
2015-02-03 10:10 ` Michael S. Tsirkin
2015-02-03 14:27 ` Al Viro
2015-02-03 15:19 ` Michael S. Tsirkin [this message]
2014-11-25 14:02 ` [PATCH v2 09/17] kill zerocopy_sg_from_iovec() Al Viro
2014-11-25 14:02 ` [PATCH v2 10/17] switch AF_PACKET and AF_UNIX to skb_copy_datagram_from_iter() Al Viro
2014-11-25 14:02 ` [PATCH v2 11/17] switch sctp_user_addto_chunk() and sctp_datamsg_from_user() to passing iov_iter Al Viro
2014-11-25 14:02 ` [PATCH v2 12/17] tipc_sendmsg(): pass msghdr instead of its ->msg_iov Al Viro
2014-11-25 14:02 ` [PATCH v2 13/17] tipc_msg_build(): " Al Viro
2014-11-25 14:02 ` [PATCH v2 14/17] vmci_transport: switch ->enqeue_dgram, ->enqueue_stream and ->dequeue_stream to msghdr Al Viro
2014-11-25 14:02 ` [PATCH v2 15/17] [atm] switch vcc_sendmsg() to copy_from_iter() Al Viro
2014-11-25 14:02 ` [PATCH v2 16/17] rds: switch ->inc_copy_to_user() to passing iov_iter Al Viro
2014-11-25 14:02 ` [PATCH v2 17/17] rds: switch rds_message_copy_from_user() to iov_iter Al Viro
2014-11-22 17:48 ` [RFC] situation with csum_and_copy_... API Linus Torvalds
2014-11-21 4:17 ` Nicholas A. Bellinger
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