linux/net/core/sysctl_net_core.c
Ingo Molnar c5905afb0e static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]()
So here's a boot tested patch on top of Jason's series that does
all the cleanups I talked about and turns jump labels into a
more intuitive to use facility. It should also address the
various misconceptions and confusions that surround jump labels.

Typical usage scenarios:

        #include <linux/static_key.h>

        struct static_key key = STATIC_KEY_INIT_TRUE;

        if (static_key_false(&key))
                do unlikely code
        else
                do likely code

Or:

        if (static_key_true(&key))
                do likely code
        else
                do unlikely code

The static key is modified via:

        static_key_slow_inc(&key);
        ...
        static_key_slow_dec(&key);

The 'slow' prefix makes it abundantly clear that this is an
expensive operation.

I've updated all in-kernel code to use this everywhere. Note
that I (intentionally) have not pushed through the rename
blindly through to the lowest levels: the actual jump-label
patching arch facility should be named like that, so we want to
decouple jump labels from the static-key facility a bit.

On non-jump-label enabled architectures static keys default to
likely()/unlikely() branches.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jason Baron <jbaron@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: a.p.zijlstra@chello.nl
Cc: mathieu.desnoyers@efficios.com
Cc: davem@davemloft.net
Cc: ddaney.cavm@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20120222085809.GA26397@elte.hu
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-02-24 10:05:59 +01:00

265 lines
5.6 KiB
C

/* -*- linux-c -*-
* sysctl_net_core.c: sysctl interface to net core subsystem.
*
* Begun April 1, 1996, Mike Shaver.
* Added /proc/sys/net/core directory entry (empty =) ). [MS]
*/
#include <linux/mm.h>
#include <linux/sysctl.h>
#include <linux/module.h>
#include <linux/socket.h>
#include <linux/netdevice.h>
#include <linux/ratelimit.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <net/ip.h>
#include <net/sock.h>
#include <net/net_ratelimit.h>
#ifdef CONFIG_RPS
static int rps_sock_flow_sysctl(ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
unsigned int orig_size, size;
int ret, i;
ctl_table tmp = {
.data = &size,
.maxlen = sizeof(size),
.mode = table->mode
};
struct rps_sock_flow_table *orig_sock_table, *sock_table;
static DEFINE_MUTEX(sock_flow_mutex);
mutex_lock(&sock_flow_mutex);
orig_sock_table = rcu_dereference_protected(rps_sock_flow_table,
lockdep_is_held(&sock_flow_mutex));
size = orig_size = orig_sock_table ? orig_sock_table->mask + 1 : 0;
ret = proc_dointvec(&tmp, write, buffer, lenp, ppos);
if (write) {
if (size) {
if (size > 1<<30) {
/* Enforce limit to prevent overflow */
mutex_unlock(&sock_flow_mutex);
return -EINVAL;
}
size = roundup_pow_of_two(size);
if (size != orig_size) {
sock_table =
vmalloc(RPS_SOCK_FLOW_TABLE_SIZE(size));
if (!sock_table) {
mutex_unlock(&sock_flow_mutex);
return -ENOMEM;
}
sock_table->mask = size - 1;
} else
sock_table = orig_sock_table;
for (i = 0; i < size; i++)
sock_table->ents[i] = RPS_NO_CPU;
} else
sock_table = NULL;
if (sock_table != orig_sock_table) {
rcu_assign_pointer(rps_sock_flow_table, sock_table);
if (sock_table)
static_key_slow_inc(&rps_needed);
if (orig_sock_table) {
static_key_slow_dec(&rps_needed);
synchronize_rcu();
vfree(orig_sock_table);
}
}
}
mutex_unlock(&sock_flow_mutex);
return ret;
}
#endif /* CONFIG_RPS */
static struct ctl_table net_core_table[] = {
#ifdef CONFIG_NET
{
.procname = "wmem_max",
.data = &sysctl_wmem_max,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "rmem_max",
.data = &sysctl_rmem_max,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "wmem_default",
.data = &sysctl_wmem_default,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "rmem_default",
.data = &sysctl_rmem_default,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "dev_weight",
.data = &weight_p,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "netdev_max_backlog",
.data = &netdev_max_backlog,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
#ifdef CONFIG_BPF_JIT
{
.procname = "bpf_jit_enable",
.data = &bpf_jit_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
#endif
{
.procname = "netdev_tstamp_prequeue",
.data = &netdev_tstamp_prequeue,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "message_cost",
.data = &net_ratelimit_state.interval,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
{
.procname = "message_burst",
.data = &net_ratelimit_state.burst,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "optmem_max",
.data = &sysctl_optmem_max,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
#ifdef CONFIG_RPS
{
.procname = "rps_sock_flow_entries",
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = rps_sock_flow_sysctl
},
#endif
#endif /* CONFIG_NET */
{
.procname = "netdev_budget",
.data = &netdev_budget,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{
.procname = "warnings",
.data = &net_msg_warn,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{ }
};
static struct ctl_table netns_core_table[] = {
{
.procname = "somaxconn",
.data = &init_net.core.sysctl_somaxconn,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
{ }
};
__net_initdata struct ctl_path net_core_path[] = {
{ .procname = "net", },
{ .procname = "core", },
{ },
};
static __net_init int sysctl_core_net_init(struct net *net)
{
struct ctl_table *tbl;
net->core.sysctl_somaxconn = SOMAXCONN;
tbl = netns_core_table;
if (!net_eq(net, &init_net)) {
tbl = kmemdup(tbl, sizeof(netns_core_table), GFP_KERNEL);
if (tbl == NULL)
goto err_dup;
tbl[0].data = &net->core.sysctl_somaxconn;
}
net->core.sysctl_hdr = register_net_sysctl_table(net,
net_core_path, tbl);
if (net->core.sysctl_hdr == NULL)
goto err_reg;
return 0;
err_reg:
if (tbl != netns_core_table)
kfree(tbl);
err_dup:
return -ENOMEM;
}
static __net_exit void sysctl_core_net_exit(struct net *net)
{
struct ctl_table *tbl;
tbl = net->core.sysctl_hdr->ctl_table_arg;
unregister_net_sysctl_table(net->core.sysctl_hdr);
BUG_ON(tbl == netns_core_table);
kfree(tbl);
}
static __net_initdata struct pernet_operations sysctl_core_ops = {
.init = sysctl_core_net_init,
.exit = sysctl_core_net_exit,
};
static __init int sysctl_core_init(void)
{
static struct ctl_table empty[1];
register_sysctl_paths(net_core_path, empty);
register_net_sysctl_rotable(net_core_path, net_core_table);
return register_pernet_subsys(&sysctl_core_ops);
}
fs_initcall(sysctl_core_init);