linux/net/smc/smc_tx.h
Tony Lu ea785a1a57 net/smc: Send directly when TCP_CORK is cleared
According to the man page of TCP_CORK [1], if set, don't send out
partial frames. All queued partial frames are sent when option is
cleared again.

When applications call setsockopt to disable TCP_CORK, this call is
protected by lock_sock(), and tries to mod_delayed_work() to 0, in order
to send pending data right now. However, the delayed work smc_tx_work is
also protected by lock_sock(). There introduces lock contention for
sending data.

To fix it, send pending data directly which acts like TCP, without
lock_sock() protected in the context of setsockopt (already lock_sock()ed),
and cancel unnecessary dealyed work, which is protected by lock.

[1] https://linux.die.net/man/7/tcp

Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-01-31 15:08:20 +00:00

41 lines
1.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/*
* Shared Memory Communications over RDMA (SMC-R) and RoCE
*
* Manage send buffer
*
* Copyright IBM Corp. 2016
*
* Author(s): Ursula Braun <ubraun@linux.vnet.ibm.com>
*/
#ifndef SMC_TX_H
#define SMC_TX_H
#include <linux/socket.h>
#include <linux/types.h>
#include "smc.h"
#include "smc_cdc.h"
static inline int smc_tx_prepared_sends(struct smc_connection *conn)
{
union smc_host_cursor sent, prep;
smc_curs_copy(&sent, &conn->tx_curs_sent, conn);
smc_curs_copy(&prep, &conn->tx_curs_prep, conn);
return smc_curs_diff(conn->sndbuf_desc->len, &sent, &prep);
}
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_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);
int smcd_tx_ism_write(struct smc_connection *conn, void *data, size_t len,
u32 offset, int signal);
#endif /* SMC_TX_H */