From: Mina Almasry <almasrymina@google.com>
To: Stanislav Fomichev <sdf@google.com>
Cc: "Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
"David Ahern" <dsahern@kernel.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
"Arnd Bergmann" <arnd@arndb.de>, "Shuah Khan" <shuah@kernel.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Christian König" <christian.koenig@amd.com>,
"Shakeel Butt" <shakeelb@google.com>,
"Jeroen de Borst" <jeroendb@google.com>,
"Praveen Kaligineedi" <pkaligineedi@google.com>,
"Willem de Bruijn" <willemb@google.com>,
"Kaiyuan Zhang" <kaiyuanz@google.com>
Subject: Re: [RFC PATCH v3 09/12] net: add support for skbs with unreadable frags
Date: Tue, 7 Nov 2023 11:53:22 -0800 [thread overview]
Message-ID: <CAHS8izNTDsHTahkd17zQVQnjzniZAk-dKNs-Mq0E4shdrXOJbg@mail.gmail.com> (raw)
In-Reply-To: <ZUmNk98LyO_Ntcy7@google.com>
On Mon, Nov 6, 2023 at 5:06 PM Stanislav Fomichev <sdf@google.com> wrote:
[..]
> > > > And the socket has to know this association; otherwise those tokens
> > > > are useless since they don't carry anything to identify the dmabuf.
> > > >
> > > > I think my other issue with MSG_SOCK_DEVMEM being on recvmsg is that
> > > > it somehow implies that I have an option of passing or not passing it
> > > > for an individual system call.
> >
> > You do have the option of passing it or not passing it per system
> > call. The MSG_SOCK_DEVMEM says the application is willing to receive
> > devmem cmsgs - that's all. The application doesn't get to decide
> > whether it's actually going to receive a devmem cmsg or not, because
> > that's dictated by the type of skb that is present in the receive
> > queue, and not up to the application. I should explain this in the
> > commit message...
>
> What would be the case of passing it or not passing it? Some fallback to
> the host memory after flow steering update? Yeah, would be useful to
> document those constrains. I'd lean on starting stricter and relaxing
> those conditions if we find the use-cases.
>
MSG_SOCK_DEVMEM (or its replacement SOCK_DEVMEM or SO_SOCK_DEVMEM),
just says that the application is able to receive devmem cmsgs and
will parse them. The use case for not setting that flag is existing
applications that are not aware of devmem cmsgs. I don't want those
applications to think they're receiving data in the linear buffer only
to find out that the data is in devmem and they ignored the devmem
cmsg.
So, what happens:
- MSG_SOCK_DEVMEM provided and next skb in the queue is devmem:
application receives cmsgs.
- MSG_SOCK_DEVMEM provided and next skb in the queue is non-devmem:
application receives in the linear buffer.
- MSG_SOCK_DEVMEM not provided and net skb is devmem: application
receives EFAULT.
- MSG_SOCK_DEVMEM not provided and next skb is non-devmem: application
receives in the linear buffer.
My bad on not including some docs about this. The next version should
have the commit message beefed up to explain all this, or a docs
patch.
--
Thanks,
Mina
WARNING: multiple messages have this Message-ID (diff)
From: Mina Almasry <almasrymina@google.com>
To: Stanislav Fomichev <sdf@google.com>
Cc: "Kaiyuan Zhang" <kaiyuanz@google.com>,
dri-devel@lists.freedesktop.org,
"Eric Dumazet" <edumazet@google.com>,
linux-kselftest@vger.kernel.org, "Shuah Khan" <shuah@kernel.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
linux-arch@vger.kernel.org,
"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
"Jeroen de Borst" <jeroendb@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
linux-media@vger.kernel.org,
"Jesper Dangaard Brouer" <hawk@kernel.org>,
"Arnd Bergmann" <arnd@arndb.de>,
linaro-mm-sig@lists.linaro.org,
"Shakeel Butt" <shakeelb@google.com>,
"Willem de Bruijn" <willemb@google.com>,
netdev@vger.kernel.org, "David Ahern" <dsahern@kernel.org>,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
linux-kernel@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
"Praveen Kaligineedi" <pkaligineedi@google.com>,
"Christian König" <christian.koenig@amd.com>
Subject: Re: [RFC PATCH v3 09/12] net: add support for skbs with unreadable frags
Date: Tue, 7 Nov 2023 11:53:22 -0800 [thread overview]
Message-ID: <CAHS8izNTDsHTahkd17zQVQnjzniZAk-dKNs-Mq0E4shdrXOJbg@mail.gmail.com> (raw)
In-Reply-To: <ZUmNk98LyO_Ntcy7@google.com>
On Mon, Nov 6, 2023 at 5:06 PM Stanislav Fomichev <sdf@google.com> wrote:
[..]
> > > > And the socket has to know this association; otherwise those tokens
> > > > are useless since they don't carry anything to identify the dmabuf.
> > > >
> > > > I think my other issue with MSG_SOCK_DEVMEM being on recvmsg is that
> > > > it somehow implies that I have an option of passing or not passing it
> > > > for an individual system call.
> >
> > You do have the option of passing it or not passing it per system
> > call. The MSG_SOCK_DEVMEM says the application is willing to receive
> > devmem cmsgs - that's all. The application doesn't get to decide
> > whether it's actually going to receive a devmem cmsg or not, because
> > that's dictated by the type of skb that is present in the receive
> > queue, and not up to the application. I should explain this in the
> > commit message...
>
> What would be the case of passing it or not passing it? Some fallback to
> the host memory after flow steering update? Yeah, would be useful to
> document those constrains. I'd lean on starting stricter and relaxing
> those conditions if we find the use-cases.
>
MSG_SOCK_DEVMEM (or its replacement SOCK_DEVMEM or SO_SOCK_DEVMEM),
just says that the application is able to receive devmem cmsgs and
will parse them. The use case for not setting that flag is existing
applications that are not aware of devmem cmsgs. I don't want those
applications to think they're receiving data in the linear buffer only
to find out that the data is in devmem and they ignored the devmem
cmsg.
So, what happens:
- MSG_SOCK_DEVMEM provided and next skb in the queue is devmem:
application receives cmsgs.
- MSG_SOCK_DEVMEM provided and next skb in the queue is non-devmem:
application receives in the linear buffer.
- MSG_SOCK_DEVMEM not provided and net skb is devmem: application
receives EFAULT.
- MSG_SOCK_DEVMEM not provided and next skb is non-devmem: application
receives in the linear buffer.
My bad on not including some docs about this. The next version should
have the commit message beefed up to explain all this, or a docs
patch.
--
Thanks,
Mina
next prev parent reply other threads:[~2023-11-07 19:53 UTC|newest]
Thread overview: 254+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-06 2:43 [RFC PATCH v3 00/12] Device Memory TCP Mina Almasry
2023-11-06 2:43 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 01/12] net: page_pool: factor out releasing DMA from releasing the page Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 02/12] net: page_pool: create hooks for custom page providers Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-07 7:44 ` Yunsheng Lin
2023-11-07 7:44 ` Yunsheng Lin
2023-11-09 11:09 ` Paolo Abeni
2023-11-09 11:09 ` Paolo Abeni
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-13 3:28 ` Mina Almasry
2023-11-13 3:28 ` Mina Almasry
2023-11-13 22:10 ` Jakub Kicinski
2023-11-13 22:10 ` Jakub Kicinski
2023-11-06 2:44 ` [RFC PATCH v3 03/12] net: netdev netlink api to bind dma-buf to a net device Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-10 23:16 ` Jakub Kicinski
2023-11-10 23:16 ` Jakub Kicinski
2023-11-06 2:44 ` [RFC PATCH v3 04/12] netdev: support binding dma-buf to netdevice Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-07 7:46 ` Yunsheng Lin
2023-11-07 7:46 ` Yunsheng Lin
2023-11-07 21:59 ` Mina Almasry
2023-11-07 21:59 ` Mina Almasry
2023-11-08 3:40 ` Yunsheng Lin
2023-11-08 3:40 ` Yunsheng Lin
2023-11-09 2:22 ` Mina Almasry
2023-11-09 2:22 ` Mina Almasry
2023-11-09 9:29 ` Yunsheng Lin
2023-11-09 9:29 ` Yunsheng Lin
2023-11-08 23:47 ` David Wei
2023-11-08 23:47 ` David Wei
2023-11-09 2:25 ` Mina Almasry
2023-11-09 2:25 ` Mina Almasry
2023-11-09 8:29 ` Paolo Abeni
2023-11-09 8:29 ` Paolo Abeni
2023-11-10 2:59 ` Mina Almasry
2023-11-10 2:59 ` Mina Almasry
2023-11-10 7:38 ` Yunsheng Lin
2023-11-10 7:38 ` Yunsheng Lin
2023-11-10 9:45 ` Mina Almasry
2023-11-10 9:45 ` Mina Almasry
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-11 2:19 ` Mina Almasry
2023-11-11 2:19 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 05/12] netdev: netdevice devmem allocator Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 23:44 ` David Ahern
2023-11-06 23:44 ` David Ahern
2023-11-07 22:10 ` Mina Almasry
2023-11-07 22:10 ` Mina Almasry
2023-11-07 22:55 ` David Ahern
2023-11-07 22:55 ` David Ahern
2023-11-07 23:03 ` Mina Almasry
2023-11-07 23:03 ` Mina Almasry
2023-11-09 1:15 ` David Wei
2023-11-09 1:15 ` David Wei
2023-11-10 14:26 ` Pavel Begunkov
2023-11-10 14:26 ` Pavel Begunkov
2023-11-11 17:19 ` David Ahern
2023-11-11 17:19 ` David Ahern
2023-11-14 16:09 ` Pavel Begunkov
2023-11-14 16:09 ` Pavel Begunkov
2023-11-09 1:00 ` David Wei
2023-11-09 1:00 ` David Wei
2023-11-08 3:48 ` Yunsheng Lin
2023-11-08 3:48 ` Yunsheng Lin
2023-11-09 1:41 ` Mina Almasry
2023-11-09 1:41 ` Mina Almasry
2023-11-07 7:45 ` Yunsheng Lin
2023-11-07 7:45 ` Yunsheng Lin
2023-11-09 8:44 ` Paolo Abeni
2023-11-09 8:44 ` Paolo Abeni
2023-11-06 2:44 ` [RFC PATCH v3 06/12] memory-provider: dmabuf devmem memory provider Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 21:02 ` Stanislav Fomichev
2023-11-06 21:02 ` Stanislav Fomichev
2023-11-06 23:49 ` David Ahern
2023-11-06 23:49 ` David Ahern
2023-11-08 0:02 ` Mina Almasry
2023-11-08 0:02 ` Mina Almasry
2023-11-08 0:10 ` David Ahern
2023-11-08 0:10 ` David Ahern
2023-11-10 23:16 ` Jakub Kicinski
2023-11-10 23:16 ` Jakub Kicinski
2023-11-13 4:54 ` Mina Almasry
2023-11-13 4:54 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 07/12] page-pool: device memory support Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-07 8:00 ` Yunsheng Lin
2023-11-07 8:00 ` Yunsheng Lin
2023-11-07 21:56 ` Mina Almasry
2023-11-07 21:56 ` Mina Almasry
2023-11-08 10:56 ` Yunsheng Lin
2023-11-08 10:56 ` Yunsheng Lin
2023-11-09 3:20 ` Mina Almasry
2023-11-09 3:20 ` Mina Almasry
2023-11-09 9:30 ` Yunsheng Lin
2023-11-09 9:30 ` Yunsheng Lin
2023-11-09 12:20 ` Mina Almasry
2023-11-09 12:20 ` Mina Almasry
2023-11-09 13:23 ` Yunsheng Lin
2023-11-09 13:23 ` Yunsheng Lin
2023-11-09 14:23 ` Christian König
2023-11-09 9:01 ` Paolo Abeni
2023-11-09 9:01 ` Paolo Abeni
2023-11-06 2:44 ` [RFC PATCH v3 08/12] net: support non paged skb frags Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-07 9:00 ` Yunsheng Lin
2023-11-07 9:00 ` Yunsheng Lin
2023-11-07 21:19 ` Mina Almasry
2023-11-07 21:19 ` Mina Almasry
2023-11-08 11:25 ` Yunsheng Lin
2023-11-08 11:25 ` Yunsheng Lin
2023-11-09 9:14 ` Paolo Abeni
2023-11-09 9:14 ` Paolo Abeni
2023-11-10 4:06 ` Mina Almasry
2023-11-10 4:06 ` Mina Almasry
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-13 6:05 ` Mina Almasry
2023-11-13 6:05 ` Mina Almasry
2023-11-13 22:17 ` Jakub Kicinski
2023-11-13 22:17 ` Jakub Kicinski
2023-11-06 2:44 ` [RFC PATCH v3 09/12] net: add support for skbs with unreadable frags Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 18:47 ` Stanislav Fomichev
2023-11-06 18:47 ` Stanislav Fomichev
2023-11-06 19:34 ` David Ahern
2023-11-06 19:34 ` David Ahern
2023-11-06 20:31 ` Mina Almasry
2023-11-06 20:31 ` Mina Almasry
2023-11-06 21:59 ` Stanislav Fomichev
2023-11-06 21:59 ` Stanislav Fomichev
2023-11-06 22:18 ` Mina Almasry
2023-11-06 22:18 ` Mina Almasry
2023-11-06 22:59 ` Stanislav Fomichev
2023-11-06 22:59 ` Stanislav Fomichev
2023-11-06 23:14 ` Kaiyuan Zhang
2023-11-06 23:27 ` Mina Almasry
2023-11-06 23:27 ` Mina Almasry
2023-11-06 23:55 ` Stanislav Fomichev
2023-11-06 23:55 ` Stanislav Fomichev
2023-11-07 0:07 ` Willem de Bruijn
2023-11-07 0:07 ` Willem de Bruijn
2023-11-07 0:14 ` Stanislav Fomichev
2023-11-07 0:14 ` Stanislav Fomichev
2023-11-07 0:59 ` Stanislav Fomichev
2023-11-07 0:59 ` Stanislav Fomichev
2023-11-07 2:23 ` Willem de Bruijn
2023-11-07 2:23 ` Willem de Bruijn
2023-11-07 17:44 ` Stanislav Fomichev
2023-11-07 17:44 ` Stanislav Fomichev
2023-11-07 17:57 ` Willem de Bruijn
2023-11-07 17:57 ` Willem de Bruijn
2023-11-07 18:14 ` Stanislav Fomichev
2023-11-07 18:14 ` Stanislav Fomichev
2023-11-07 0:20 ` Mina Almasry
2023-11-07 0:20 ` Mina Almasry
2023-11-07 1:06 ` Stanislav Fomichev
2023-11-07 1:06 ` Stanislav Fomichev
2023-11-07 19:53 ` Mina Almasry [this message]
2023-11-07 19:53 ` Mina Almasry
2023-11-07 21:05 ` Stanislav Fomichev
2023-11-07 21:05 ` Stanislav Fomichev
2023-11-07 21:17 ` Eric Dumazet
2023-11-07 21:17 ` Eric Dumazet
2023-11-07 22:23 ` Stanislav Fomichev
2023-11-07 22:23 ` Stanislav Fomichev
2023-11-10 23:17 ` Jakub Kicinski
2023-11-10 23:17 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-07 1:09 ` David Ahern
2023-11-07 1:09 ` David Ahern
2023-11-06 23:37 ` David Ahern
2023-11-06 23:37 ` David Ahern
2023-11-07 0:03 ` Mina Almasry
2023-11-07 0:03 ` Mina Almasry
2023-11-06 20:56 ` Stanislav Fomichev
2023-11-06 20:56 ` Stanislav Fomichev
2023-11-07 0:16 ` David Ahern
2023-11-07 0:16 ` David Ahern
2023-11-07 0:23 ` Mina Almasry
2023-11-07 0:23 ` Mina Almasry
2023-11-08 14:43 ` David Laight
2023-11-08 14:43 ` David Laight
2023-11-06 2:44 ` [RFC PATCH v3 10/12] tcp: RX path for devmem TCP Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 18:44 ` Stanislav Fomichev
2023-11-06 18:44 ` Stanislav Fomichev
2023-11-06 19:29 ` Mina Almasry
2023-11-06 19:29 ` Mina Almasry
2023-11-06 21:14 ` Willem de Bruijn
2023-11-06 21:14 ` Willem de Bruijn
2023-11-06 22:34 ` Stanislav Fomichev
2023-11-06 22:34 ` Stanislav Fomichev
2023-11-06 22:55 ` Willem de Bruijn
2023-11-06 22:55 ` Willem de Bruijn
2023-11-06 23:32 ` Stanislav Fomichev
2023-11-06 23:32 ` Stanislav Fomichev
2023-11-06 23:55 ` David Ahern
2023-11-06 23:55 ` David Ahern
2023-11-07 0:02 ` Willem de Bruijn
2023-11-07 0:02 ` Willem de Bruijn
2023-11-07 23:55 ` Mina Almasry
2023-11-07 23:55 ` Mina Almasry
2023-11-08 0:01 ` David Ahern
2023-11-08 0:01 ` David Ahern
2023-11-09 2:39 ` Mina Almasry
2023-11-09 2:39 ` Mina Almasry
2023-11-09 16:07 ` Edward Cree
2023-11-09 16:07 ` Edward Cree
2023-12-08 20:12 ` Pavel Begunkov
2023-12-08 20:12 ` Pavel Begunkov
2023-11-09 11:05 ` Paolo Abeni
2023-11-09 11:05 ` Paolo Abeni
2023-11-10 23:16 ` Jakub Kicinski
2023-11-10 23:16 ` Jakub Kicinski
2023-12-08 20:28 ` Pavel Begunkov
2023-12-08 20:28 ` Pavel Begunkov
2023-12-08 20:09 ` Pavel Begunkov
2023-12-08 20:09 ` Pavel Begunkov
2023-11-06 21:17 ` Stanislav Fomichev
2023-11-06 21:17 ` Stanislav Fomichev
2023-11-08 15:36 ` Edward Cree
2023-11-08 15:36 ` Edward Cree
2023-11-09 10:52 ` Paolo Abeni
2023-11-09 10:52 ` Paolo Abeni
2023-11-10 23:19 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-06 2:44 ` [RFC PATCH v3 11/12] net: add SO_DEVMEM_DONTNEED setsockopt to release RX pages Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 12/12] selftests: add ncdevmem, netcat for devmem TCP Mina Almasry
2023-11-06 2:44 ` Mina Almasry
2023-11-09 11:03 ` Paolo Abeni
2023-11-09 11:03 ` Paolo Abeni
2023-11-10 23:13 ` Jakub Kicinski
2023-11-10 23:13 ` Jakub Kicinski
2023-11-11 2:27 ` Mina Almasry
2023-11-11 2:27 ` Mina Almasry
2023-11-11 2:35 ` Jakub Kicinski
2023-11-11 2:35 ` Jakub Kicinski
2023-11-13 4:08 ` Mina Almasry
2023-11-13 4:08 ` Mina Almasry
2023-11-13 22:20 ` Jakub Kicinski
2023-11-13 22:20 ` Jakub Kicinski
2023-11-10 23:17 ` Jakub Kicinski
2023-11-10 23:17 ` Jakub Kicinski
2023-11-07 15:18 ` [RFC PATCH v3 00/12] Device Memory TCP David Ahern
2023-11-07 15:18 ` David Ahern
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