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Message-ID: <b9a15afe-c65d-5cf3-e6c7-eaec46cc99c1@linux.alibaba.com>
Date: Fri, 28 Apr 2023 11:12:03 +0800
From: "D. Wythe" <alibuda@...ux.alibaba.com>
To: David Howells <dhowells@...hat.com>,
Matthew Wilcox <willy@...radead.org>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Al Viro <viro@...iv.linux.org.uk>,
Christoph Hellwig <hch@...radead.org>,
Jens Axboe <axboe@...nel.dk>, Jeff Layton <jlayton@...nel.org>,
Christian Brauner <brauner@...nel.org>,
Chuck Lever III <chuck.lever@...cle.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
netdev@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Karsten Graul <kgraul@...ux.ibm.com>,
Wenjia Zhang <wenjia@...ux.ibm.com>,
Jan Karcher <jaka@...ux.ibm.com>, linux-s390@...r.kernel.org
Subject: Re: [PATCH v3 51/55] smc: Drop smc_sendpage() in favour of
smc_sendmsg() + MSG_SPLICE_PAGES
On 4/26/23 9:07 PM, D. Wythe wrote:
>
> Hi David,
>
> Fallback is one of the most important features of SMC, which
> automatically downgrades to TCP
> when SMC discovers that the peer does not support SMC. After fallback,
> SMC hopes the the ability can be
> consistent with that of TCP sock. If you delete the smc_sendpage, when
> fallback occurs, it means that the sock after the fallback
> loses the ability of sendpage( tcp_sendpage).
>
> Thanks
> D. Wythe
Sorry, I missed the key email context. The problem mentioned here does
not exist ...
>
> On 4/1/23 12:09 AM, David Howells wrote:
>> Drop the smc_sendpage() code as smc_sendmsg() just passes the call
>> down to
>> the underlying TCP socket and smc_tx_sendpage() is just a wrapper around
>> its sendmsg implementation.
>> Signed-off-by: David Howells <dhowells@...hat.com>
>> cc: Karsten Graul <kgraul@...ux.ibm.com>
>> cc: Wenjia Zhang <wenjia@...ux.ibm.com>
>> cc: Jan Karcher <jaka@...ux.ibm.com>
>> cc: "David S. Miller" <davem@...emloft.net>
>> cc: Eric Dumazet <edumazet@...gle.com>
>> cc: Jakub Kicinski <kuba@...nel.org>
>> cc: Paolo Abeni <pabeni@...hat.com>
>> cc: Jens Axboe <axboe@...nel.dk>
>> cc: Matthew Wilcox <willy@...radead.org>
>> cc: linux-s390@...r.kernel.org
>> cc: netdev@...r.kernel.org
>> ---
>> net/smc/af_smc.c | 29 -----------------------------
>> net/smc/smc_stats.c | 2 +-
>> net/smc/smc_stats.h | 1 -
>> net/smc/smc_tx.c | 16 ----------------
>> net/smc/smc_tx.h | 2 --
>> 5 files changed, 1 insertion(+), 49 deletions(-)
>>
>> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
>> index a4cccdfdc00a..d4113c8a7cda 100644
>> --- a/net/smc/af_smc.c
>> +++ b/net/smc/af_smc.c
>> @@ -3125,34 +3125,6 @@ static int smc_ioctl(struct socket *sock,
>> unsigned int cmd,
>> return put_user(answ, (int __user *)arg);
>> }
>> -static ssize_t smc_sendpage(struct socket *sock, struct page *page,
>> - int offset, size_t size, int flags)
>> -{
>> - struct sock *sk = sock->sk;
>> - struct smc_sock *smc;
>> - int rc = -EPIPE;
>> -
>> - smc = smc_sk(sk);
>> - lock_sock(sk);
>> - if (sk->sk_state != SMC_ACTIVE) {
>> - release_sock(sk);
>> - goto out;
>> - }
>> - release_sock(sk);
>> - if (smc->use_fallback) {
>> - rc = kernel_sendpage(smc->clcsock, page, offset,
>> - size, flags);
>> - } else {
>> - lock_sock(sk);
>> - rc = smc_tx_sendpage(smc, page, offset, size, flags);
>> - release_sock(sk);
>> - SMC_STAT_INC(smc, sendpage_cnt);
>> - }
>> -
>> -out:
>> - return rc;
>> -}
>> -
>> /* Map the affected portions of the rmbe into an spd, note the
>> number of bytes
>> * to splice in conn->splice_pending, and press 'go'. Delays
>> consumer cursor
>> * updates till whenever a respective page has been fully processed.
>> @@ -3224,7 +3196,6 @@ static const struct proto_ops smc_sock_ops = {
>> .sendmsg = smc_sendmsg,
>> .recvmsg = smc_recvmsg,
>> .mmap = sock_no_mmap,
>> - .sendpage = smc_sendpage,
>> .splice_read = smc_splice_read,
>> };
>> diff --git a/net/smc/smc_stats.c b/net/smc/smc_stats.c
>> index e80e34f7ac15..ca14c0f3a07d 100644
>> --- a/net/smc/smc_stats.c
>> +++ b/net/smc/smc_stats.c
>> @@ -227,7 +227,7 @@ static int smc_nl_fill_stats_tech_data(struct
>> sk_buff *skb,
>> SMC_NLA_STATS_PAD))
>> goto errattr;
>> if (nla_put_u64_64bit(skb, SMC_NLA_STATS_T_SENDPAGE_CNT,
>> - smc_tech->sendpage_cnt,
>> + 0,
>> SMC_NLA_STATS_PAD))
>> goto errattr;
>> if (nla_put_u64_64bit(skb, SMC_NLA_STATS_T_CORK_CNT,
>> diff --git a/net/smc/smc_stats.h b/net/smc/smc_stats.h
>> index 84b7ecd8c05c..b60fe1eb37ab 100644
>> --- a/net/smc/smc_stats.h
>> +++ b/net/smc/smc_stats.h
>> @@ -71,7 +71,6 @@ struct smc_stats_tech {
>> u64 clnt_v2_succ_cnt;
>> u64 srv_v1_succ_cnt;
>> u64 srv_v2_succ_cnt;
>> - u64 sendpage_cnt;
>> u64 urg_data_cnt;
>> u64 splice_cnt;
>> u64 cork_cnt;
>> diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
>> index f4b6a71ac488..d31ce8209fa2 100644
>> --- a/net/smc/smc_tx.c
>> +++ b/net/smc/smc_tx.c
>> @@ -298,22 +298,6 @@ int smc_tx_sendmsg(struct smc_sock *smc, struct
>> msghdr *msg, size_t len)
>> return rc;
>> }
>> -int smc_tx_sendpage(struct smc_sock *smc, struct page *page, int
>> offset,
>> - size_t size, int flags)
>> -{
>> - struct msghdr msg = {.msg_flags = flags};
>> - char *kaddr = kmap(page);
>> - struct kvec iov;
>> - int rc;
>> -
>> - iov.iov_base = kaddr + offset;
>> - iov.iov_len = size;
>> - iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &iov, 1, size);
>> - rc = smc_tx_sendmsg(smc, &msg, size);
>> - kunmap(page);
>> - return rc;
>> -}
>> -
>> /***************************** sndbuf consumer
>> *******************************/
>> /* sndbuf consumer: actual data transfer of one target chunk with
>> ISM write */
>> diff --git a/net/smc/smc_tx.h b/net/smc/smc_tx.h
>> index 34b578498b1f..a59f370b8b43 100644
>> --- a/net/smc/smc_tx.h
>> +++ b/net/smc/smc_tx.h
>> @@ -31,8 +31,6 @@ void smc_tx_pending(struct smc_connection *conn);
>> void smc_tx_work(struct work_struct *work);
>> void smc_tx_init(struct smc_sock *smc);
>> int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t
>> len);
>> -int smc_tx_sendpage(struct smc_sock *smc, struct page *page, int
>> offset,
>> - size_t size, int flags);
>> int smc_tx_sndbuf_nonempty(struct smc_connection *conn);
>> void smc_tx_sndbuf_nonfull(struct smc_sock *smc);
>> void smc_tx_consumer_update(struct smc_connection *conn, bool force);
>
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