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/*
* netsniff-ng - the packet sniffing beast
* By Daniel Borkmann <daniel@netsniff-ng.org>
* Copyright 2011 Daniel Borkmann.
* Subject to the GPL, version 2.
*/
#define _GNU_SOURCE
#include <search.h>
#include <limits.h>
#include <errno.h>
#include <string.h>
#include "locking.h"
#include "ct_cpusched.h"
#include "xmalloc.h"
#include "hash.h"
/* Flow to CPU mapper / scheduler to keep connection CPU-local */
struct map_entry {
int fd;
unsigned int cpu;
struct map_entry *next;
};
static struct hash_table mapper;
static unsigned int *cpu_assigned = NULL;
static unsigned int cpu_len = 0;
static struct rwlock map_lock;
void init_cpusched(unsigned int cpus)
{
rwlock_init(&map_lock);
rwlock_wr_lock(&map_lock);
cpu_len = cpus;
cpu_assigned = xzmalloc(cpus * sizeof(*cpu_assigned));
memset(&mapper, 0, sizeof(mapper));
init_hash(&mapper);
rwlock_unlock(&map_lock);
}
static int get_appropriate_cpu(void)
{
int i, cpu = 0;
int work = INT_MAX;
for (i = 0; i < cpu_len; ++i) {
if (cpu_assigned[i] < work) {
work = cpu_assigned[i];
cpu = i;
}
}
return cpu;
}
unsigned int socket_to_cpu(int fd)
{
int cpu = 0;
struct map_entry *entry;
errno = 0;
rwlock_rd_lock(&map_lock);
entry = lookup_hash(fd, &mapper);
while (entry && fd != entry->fd)
entry = entry->next;
if (entry && fd == entry->fd)
cpu = entry->cpu;
else
errno = ENOENT;
rwlock_unlock(&map_lock);
return cpu;
}
unsigned int register_socket(int fd)
{
void **pos;
struct map_entry *entry;
rwlock_wr_lock(&map_lock);
entry = xzmalloc(sizeof(*entry));
entry->fd = fd;
entry->cpu = get_appropriate_cpu();
cpu_assigned[entry->cpu]++;
pos = insert_hash(entry->fd, entry, &mapper);
if (pos) {
entry->next = (*pos);
(*pos) = entry;
}
rwlock_unlock(&map_lock);
return entry->cpu;
}
static struct map_entry *socket_to_map_entry(int fd)
{
struct map_entry *entry, *ret = NULL;
errno = 0;
rwlock_rd_lock(&map_lock);
entry = lookup_hash(fd, &mapper);
while (entry && fd != entry->fd)
entry = entry->next;
if (entry && fd == entry->fd)
ret = entry;
else
errno = ENOENT;
rwlock_unlock(&map_lock);
return ret;
}
void unregister_socket(int fd)
{
struct map_entry *pos;
struct map_entry *entry = socket_to_map_entry(fd);
if (!entry == 0 && errno == ENOENT)
return;
rwlock_wr_lock(&map_lock);
cpu_assigned[entry->cpu]--;
pos = remove_hash(entry->fd, entry, entry->next, &mapper);
while (pos && pos->next && pos->next != entry)
pos = pos->next;
if (pos && pos->next && pos->next == entry)
pos->next = entry->next;
entry->next = NULL;
xfree(entry);
rwlock_unlock(&map_lock);
}
static int cleanup_batch(void *ptr)
{
struct map_entry *next;
struct map_entry *e = ptr;
if (!e)
return 0;
while ((next = e->next)) {
e->next = NULL;
xfree(e);
e = next;
}
xfree(e);
return 0;
}
void destroy_cpusched(void)
{
rwlock_wr_lock(&map_lock);
xfree(cpu_assigned);
cpu_len = 0;
for_each_hash(&mapper, cleanup_batch);
free_hash(&mapper);
rwlock_unlock(&map_lock);
rwlock_destroy(&map_lock);
}
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