From: David Ahern <dsahern@kernel.org>
To: Stanislav Fomichev <sdf@google.com>,
Mina Almasry <almasrymina@google.com>
Cc: 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>,
"Willem de Bruijn" <willemdebruijn.kernel@gmail.com>,
"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: Mon, 6 Nov 2023 12:34:52 -0700 [thread overview]
Message-ID: <19129763-6f74-4b04-8a5f-441255b76d34@kernel.org> (raw)
In-Reply-To: <ZUk03DhWxV-bOFJL@google.com>
On 11/6/23 11:47 AM, Stanislav Fomichev wrote:
> On 11/05, Mina Almasry wrote:
>> For device memory TCP, we expect the skb headers to be available in host
>> memory for access, and we expect the skb frags to be in device memory
>> and unaccessible to the host. We expect there to be no mixing and
>> matching of device memory frags (unaccessible) with host memory frags
>> (accessible) in the same skb.
>>
>> Add a skb->devmem flag which indicates whether the frags in this skb
>> are device memory frags or not.
>>
>> __skb_fill_page_desc() now checks frags added to skbs for page_pool_iovs,
>> and marks the skb as skb->devmem accordingly.
>>
>> Add checks through the network stack to avoid accessing the frags of
>> devmem skbs and avoid coalescing devmem skbs with non devmem skbs.
>>
>> Signed-off-by: Willem de Bruijn <willemb@google.com>
>> Signed-off-by: Kaiyuan Zhang <kaiyuanz@google.com>
>> Signed-off-by: Mina Almasry <almasrymina@google.com>
>>
>> ---
>> include/linux/skbuff.h | 14 +++++++-
>> include/net/tcp.h | 5 +--
>> net/core/datagram.c | 6 ++++
>> net/core/gro.c | 5 ++-
>> net/core/skbuff.c | 77 ++++++++++++++++++++++++++++++++++++------
>> net/ipv4/tcp.c | 6 ++++
>> net/ipv4/tcp_input.c | 13 +++++--
>> net/ipv4/tcp_output.c | 5 ++-
>> net/packet/af_packet.c | 4 +--
>> 9 files changed, 115 insertions(+), 20 deletions(-)
>>
>> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
>> index 1fae276c1353..8fb468ff8115 100644
>> --- a/include/linux/skbuff.h
>> +++ b/include/linux/skbuff.h
>> @@ -805,6 +805,8 @@ typedef unsigned char *sk_buff_data_t;
>> * @csum_level: indicates the number of consecutive checksums found in
>> * the packet minus one that have been verified as
>> * CHECKSUM_UNNECESSARY (max 3)
>> + * @devmem: indicates that all the fragments in this skb are backed by
>> + * device memory.
>> * @dst_pending_confirm: need to confirm neighbour
>> * @decrypted: Decrypted SKB
>> * @slow_gro: state present at GRO time, slower prepare step required
>> @@ -991,7 +993,7 @@ struct sk_buff {
>> #if IS_ENABLED(CONFIG_IP_SCTP)
>> __u8 csum_not_inet:1;
>> #endif
>> -
>> + __u8 devmem:1;
>> #if defined(CONFIG_NET_SCHED) || defined(CONFIG_NET_XGRESS)
>> __u16 tc_index; /* traffic control index */
>> #endif
>> @@ -1766,6 +1768,12 @@ static inline void skb_zcopy_downgrade_managed(struct sk_buff *skb)
>> __skb_zcopy_downgrade_managed(skb);
>> }
>>
>> +/* Return true if frags in this skb are not readable by the host. */
>> +static inline bool skb_frags_not_readable(const struct sk_buff *skb)
>> +{
>> + return skb->devmem;
>
> bikeshedding: should we also rename 'devmem' sk_buff flag to 'not_readable'?
> It better communicates the fact that the stack shouldn't dereference the
> frags (because it has 'devmem' fragments or for some other potential
> future reason).
+1.
Also, the flag on the skb is an optimization - a high level signal that
one or more frags is in unreadable memory. There is no requirement that
all of the frags are in the same memory type.
next prev parent reply other threads:[~2023-11-06 19:35 UTC|newest]
Thread overview: 126+ 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 2:44 ` [RFC PATCH v3 01/12] net: page_pool: factor out releasing DMA from releasing the page Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 02/12] net: page_pool: create hooks for custom page providers Mina Almasry
2023-11-07 7:44 ` Yunsheng Lin
2023-11-09 11:09 ` Paolo Abeni
2023-11-10 23:19 ` Jakub Kicinski
2023-11-13 3:28 ` Mina Almasry
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
2023-11-10 23:16 ` Jakub Kicinski
2023-11-06 2:44 ` [RFC PATCH v3 04/12] netdev: support binding dma-buf to netdevice Mina Almasry
2023-11-07 7:46 ` Yunsheng Lin
2023-11-07 21:59 ` Mina Almasry
2023-11-08 3:40 ` Yunsheng Lin
2023-11-09 2:22 ` Mina Almasry
2023-11-09 9:29 ` Yunsheng Lin
2023-11-08 23:47 ` David Wei
2023-11-09 2:25 ` Mina Almasry
2023-11-09 8:29 ` Paolo Abeni
2023-11-10 2:59 ` Mina Almasry
2023-11-10 7:38 ` Yunsheng Lin
2023-11-10 9:45 ` Mina Almasry
2023-11-10 23:19 ` Jakub Kicinski
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 23:44 ` David Ahern
2023-11-07 22:10 ` Mina Almasry
2023-11-07 22:55 ` David Ahern
2023-11-07 23:03 ` Mina Almasry
2023-11-09 1:15 ` David Wei
2023-11-10 14:26 ` Pavel Begunkov
2023-11-11 17:19 ` David Ahern
2023-11-14 16:09 ` Pavel Begunkov
2023-11-09 1:00 ` David Wei
2023-11-08 3:48 ` Yunsheng Lin
2023-11-09 1:41 ` Mina Almasry
2023-11-07 7:45 ` Yunsheng Lin
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 21:02 ` Stanislav Fomichev
2023-11-06 23:49 ` David Ahern
2023-11-08 0:02 ` Mina Almasry
2023-11-08 0:10 ` David Ahern
2023-11-10 23:16 ` Jakub Kicinski
2023-11-13 4:54 ` Mina Almasry
2023-11-06 2:44 ` [RFC PATCH v3 07/12] page-pool: device memory support Mina Almasry
2023-11-07 8:00 ` Yunsheng Lin
2023-11-07 21:56 ` Mina Almasry
2023-11-08 10:56 ` Yunsheng Lin
2023-11-09 3:20 ` Mina Almasry
2023-11-09 9:30 ` Yunsheng Lin
2023-11-09 12:20 ` Mina Almasry
2023-11-09 13:23 ` Yunsheng Lin
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
2023-11-07 9:00 ` Yunsheng Lin
2023-11-07 21:19 ` Mina Almasry
2023-11-08 11:25 ` Yunsheng Lin
2023-11-09 9:14 ` Paolo Abeni
2023-11-10 4:06 ` Mina Almasry
2023-11-10 23:19 ` Jakub Kicinski
2023-11-13 6:05 ` Mina Almasry
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 18:47 ` Stanislav Fomichev
2023-11-06 19:34 ` David Ahern [this message]
2023-11-06 20:31 ` Mina Almasry
2023-11-06 21:59 ` Stanislav Fomichev
2023-11-06 22:18 ` Mina Almasry
2023-11-06 22:59 ` Stanislav Fomichev
2023-11-06 23:27 ` Mina Almasry
2023-11-06 23:55 ` Stanislav Fomichev
2023-11-07 0:07 ` Willem de Bruijn
2023-11-07 0:14 ` Stanislav Fomichev
2023-11-07 0:59 ` Stanislav Fomichev
2023-11-07 2:23 ` Willem de Bruijn
2023-11-07 17:44 ` Stanislav Fomichev
2023-11-07 17:57 ` Willem de Bruijn
2023-11-07 18:14 ` Stanislav Fomichev
2023-11-07 0:20 ` Mina Almasry
2023-11-07 1:06 ` Stanislav Fomichev
2023-11-07 19:53 ` Mina Almasry
2023-11-07 21:05 ` Stanislav Fomichev
2023-11-07 21:17 ` Eric Dumazet
2023-11-07 22:23 ` Stanislav Fomichev
2023-11-10 23:17 ` Jakub Kicinski
2023-11-10 23:19 ` Jakub Kicinski
2023-11-07 1:09 ` David Ahern
2023-11-06 23:37 ` David Ahern
2023-11-07 0:03 ` Mina Almasry
2023-11-06 20:56 ` Stanislav Fomichev
2023-11-07 0:16 ` David Ahern
2023-11-07 0:23 ` Mina Almasry
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 18:44 ` Stanislav Fomichev
2023-11-06 19:29 ` Mina Almasry
2023-11-06 21:14 ` Willem de Bruijn
2023-11-06 22:34 ` Stanislav Fomichev
2023-11-06 22:55 ` Willem de Bruijn
2023-11-06 23:32 ` Stanislav Fomichev
2023-11-06 23:55 ` David Ahern
2023-11-07 0:02 ` Willem de Bruijn
2023-11-07 23:55 ` Mina Almasry
2023-11-08 0:01 ` David Ahern
2023-11-09 2:39 ` Mina Almasry
2023-11-09 16:07 ` Edward Cree
2023-12-08 20:12 ` Pavel Begunkov
2023-11-09 11:05 ` Paolo Abeni
2023-11-10 23:16 ` Jakub Kicinski
2023-12-08 20:28 ` Pavel Begunkov
2023-12-08 20:09 ` Pavel Begunkov
2023-11-06 21:17 ` Stanislav Fomichev
2023-11-08 15:36 ` Edward Cree
2023-11-09 10:52 ` Paolo Abeni
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 ` [RFC PATCH v3 12/12] selftests: add ncdevmem, netcat for devmem TCP Mina Almasry
2023-11-09 11:03 ` Paolo Abeni
2023-11-10 23:13 ` Jakub Kicinski
2023-11-11 2:27 ` Mina Almasry
2023-11-11 2:35 ` Jakub Kicinski
2023-11-13 4:08 ` Mina Almasry
2023-11-13 22:20 ` Jakub Kicinski
2023-11-10 23:17 ` Jakub Kicinski
2023-11-07 15:18 ` [RFC PATCH v3 00/12] Device Memory TCP David Ahern
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