root/net/smc/smc_sysctl.c
// SPDX-License-Identifier: GPL-2.0
/*
 *  Shared Memory Communications over RDMA (SMC-R) and RoCE
 *
 *  smc_sysctl.c: sysctl interface to SMC subsystem.
 *
 *  Copyright (c) 2022, Alibaba Inc.
 *
 *  Author: Tony Lu <tonylu@linux.alibaba.com>
 *
 */

#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/bpf.h>
#include <net/net_namespace.h>

#include "smc.h"
#include "smc_core.h"
#include "smc_llc.h"
#include "smc_sysctl.h"
#include "smc_hs_bpf.h"

static int min_sndbuf = SMC_BUF_MIN_SIZE;
static int min_rcvbuf = SMC_BUF_MIN_SIZE;
static int max_sndbuf = INT_MAX / 2;
static int max_rcvbuf = INT_MAX / 2;
static const int net_smc_wmem_init = (64 * 1024);
static const int net_smc_rmem_init = (64 * 1024);
static int links_per_lgr_min = SMC_LINKS_ADD_LNK_MIN;
static int links_per_lgr_max = SMC_LINKS_ADD_LNK_MAX;
static int conns_per_lgr_min = SMC_CONN_PER_LGR_MIN;
static int conns_per_lgr_max = SMC_CONN_PER_LGR_MAX;
static unsigned int smcr_max_wr_min = 2;
static unsigned int smcr_max_wr_max = 2048;

#if IS_ENABLED(CONFIG_SMC_HS_CTRL_BPF)
static int smc_net_replace_smc_hs_ctrl(struct net *net, const char *name)
{
        struct smc_hs_ctrl *ctrl = NULL;

        rcu_read_lock();
        /* null or empty name ask to clear current ctrl */
        if (name && name[0]) {
                ctrl = smc_hs_ctrl_find_by_name(name);
                if (!ctrl) {
                        rcu_read_unlock();
                        return -EINVAL;
                }
                /* no change, just return */
                if (ctrl == rcu_dereference(net->smc.hs_ctrl)) {
                        rcu_read_unlock();
                        return 0;
                }
                if (!bpf_try_module_get(ctrl, ctrl->owner)) {
                        rcu_read_unlock();
                        return -EBUSY;
                }
        }
        /* xhcg old ctrl with the new one atomically */
        ctrl = unrcu_pointer(xchg(&net->smc.hs_ctrl, RCU_INITIALIZER(ctrl)));
        /* release old ctrl */
        if (ctrl)
                bpf_module_put(ctrl, ctrl->owner);

        rcu_read_unlock();
        return 0;
}

static int proc_smc_hs_ctrl(const struct ctl_table *ctl, int write,
                            void *buffer, size_t *lenp, loff_t *ppos)
{
        struct net *net = container_of(ctl->data, struct net, smc.hs_ctrl);
        char val[SMC_HS_CTRL_NAME_MAX];
        const struct ctl_table tbl = {
                .data = val,
                .maxlen = SMC_HS_CTRL_NAME_MAX,
        };
        struct smc_hs_ctrl *ctrl;
        int ret;

        rcu_read_lock();
        ctrl = rcu_dereference(net->smc.hs_ctrl);
        if (ctrl)
                memcpy(val, ctrl->name, sizeof(ctrl->name));
        else
                val[0] = '\0';
        rcu_read_unlock();

        ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
        if (ret)
                return ret;

        if (write)
                ret = smc_net_replace_smc_hs_ctrl(net, val);
        return ret;
}
#endif /* CONFIG_SMC_HS_CTRL_BPF */

static struct ctl_table smc_table[] = {
        {
                .procname       = "autocorking_size",
                .data           = &init_net.smc.sysctl_autocorking_size,
                .maxlen         = sizeof(unsigned int),
                .mode           = 0644,
                .proc_handler   = proc_douintvec,
        },
        {
                .procname       = "smcr_buf_type",
                .data           = &init_net.smc.sysctl_smcr_buf_type,
                .maxlen         = sizeof(unsigned int),
                .mode           = 0644,
                .proc_handler   = proc_douintvec_minmax,
                .extra1         = SYSCTL_ZERO,
                .extra2         = SYSCTL_TWO,
        },
        {
                .procname       = "smcr_testlink_time",
                .data           = &init_net.smc.sysctl_smcr_testlink_time,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_jiffies,
        },
        {
                .procname       = "wmem",
                .data           = &init_net.smc.sysctl_wmem,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = &min_sndbuf,
                .extra2         = &max_sndbuf,
        },
        {
                .procname       = "rmem",
                .data           = &init_net.smc.sysctl_rmem,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = &min_rcvbuf,
                .extra2         = &max_rcvbuf,
        },
        {
                .procname       = "smcr_max_links_per_lgr",
                .data           = &init_net.smc.sysctl_max_links_per_lgr,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = &links_per_lgr_min,
                .extra2         = &links_per_lgr_max,
        },
        {
                .procname       = "smcr_max_conns_per_lgr",
                .data           = &init_net.smc.sysctl_max_conns_per_lgr,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = &conns_per_lgr_min,
                .extra2         = &conns_per_lgr_max,
        },
        {
                .procname       = "limit_smc_hs",
                .data           = &init_net.smc.limit_smc_hs,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = SYSCTL_ZERO,
                .extra2         = SYSCTL_ONE,
        },
        {
                .procname       = "smcr_max_send_wr",
                .data           = &init_net.smc.sysctl_smcr_max_send_wr,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = &smcr_max_wr_min,
                .extra2         = &smcr_max_wr_max,
        },
        {
                .procname       = "smcr_max_recv_wr",
                .data           = &init_net.smc.sysctl_smcr_max_recv_wr,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_dointvec_minmax,
                .extra1         = &smcr_max_wr_min,
                .extra2         = &smcr_max_wr_max,
        },
#if IS_ENABLED(CONFIG_SMC_HS_CTRL_BPF)
        {
                .procname       = "hs_ctrl",
                .data           = &init_net.smc.hs_ctrl,
                .mode           = 0644,
                .maxlen         = SMC_HS_CTRL_NAME_MAX,
                .proc_handler   = proc_smc_hs_ctrl,
        },
#endif /* CONFIG_SMC_HS_CTRL_BPF */
};

int __net_init smc_sysctl_net_init(struct net *net)
{
        size_t table_size = ARRAY_SIZE(smc_table);
        struct ctl_table *table;

        table = smc_table;
        if (!net_eq(net, &init_net)) {
                int i;
#if IS_ENABLED(CONFIG_SMC_HS_CTRL_BPF)
                struct smc_hs_ctrl *ctrl;

                rcu_read_lock();
                ctrl = rcu_dereference(init_net.smc.hs_ctrl);
                if (ctrl && ctrl->flags & SMC_HS_CTRL_FLAG_INHERITABLE &&
                    bpf_try_module_get(ctrl, ctrl->owner))
                        rcu_assign_pointer(net->smc.hs_ctrl, ctrl);
                rcu_read_unlock();
#endif /* CONFIG_SMC_HS_CTRL_BPF */

                table = kmemdup(table, sizeof(smc_table), GFP_KERNEL);
                if (!table)
                        goto err_alloc;

                for (i = 0; i < table_size; i++)
                        table[i].data += (void *)net - (void *)&init_net;
        }

        net->smc.smc_hdr = register_net_sysctl_sz(net, "net/smc", table,
                                                  table_size);
        if (!net->smc.smc_hdr)
                goto err_reg;

        net->smc.sysctl_autocorking_size = SMC_AUTOCORKING_DEFAULT_SIZE;
        net->smc.sysctl_smcr_buf_type = SMCR_PHYS_CONT_BUFS;
        net->smc.sysctl_smcr_testlink_time = SMC_LLC_TESTLINK_DEFAULT_TIME;
        WRITE_ONCE(net->smc.sysctl_wmem, net_smc_wmem_init);
        WRITE_ONCE(net->smc.sysctl_rmem, net_smc_rmem_init);
        net->smc.sysctl_max_links_per_lgr = SMC_LINKS_PER_LGR_MAX_PREFER;
        net->smc.sysctl_max_conns_per_lgr = SMC_CONN_PER_LGR_PREFER;
        net->smc.sysctl_smcr_max_send_wr = SMCR_MAX_SEND_WR_DEF;
        net->smc.sysctl_smcr_max_recv_wr = SMCR_MAX_RECV_WR_DEF;
        /* disable handshake limitation by default */
        net->smc.limit_smc_hs = 0;

        return 0;

err_reg:
        if (!net_eq(net, &init_net))
                kfree(table);
err_alloc:
#if IS_ENABLED(CONFIG_SMC_HS_CTRL_BPF)
        smc_net_replace_smc_hs_ctrl(net, NULL);
#endif /* CONFIG_SMC_HS_CTRL_BPF */
        return -ENOMEM;
}

void __net_exit smc_sysctl_net_exit(struct net *net)
{
        const struct ctl_table *table;

        table = net->smc.smc_hdr->ctl_table_arg;
        unregister_net_sysctl_table(net->smc.smc_hdr);
#if IS_ENABLED(CONFIG_SMC_HS_CTRL_BPF)
        smc_net_replace_smc_hs_ctrl(net, NULL);
#endif /* CONFIG_SMC_HS_CTRL_BPF */

        if (!net_eq(net, &init_net))
                kfree(table);
}