ClabureDB: Classified Bug-Reports Database

  /*
   *  net/dccp/ccid.c
   *
   *  An implementation of the DCCP protocol
   *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   *
   *  CCID infrastructure
   *
   *        This program is free software; you can redistribute it and/or modify it
  *        under the terms of the GNU General Public License version 2 as
  *        published by the Free Software Foundation.
  */
 
 #include "ccid.h"
 
 static struct ccid_operations *ccids[CCID_MAX];
 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
 static atomic_t ccids_lockct = ATOMIC_INIT(0);
 static DEFINE_SPINLOCK(ccids_lock);
 
 /*
  * The strategy is: modifications ccids vector are short, do not sleep and
  * veeery rare, but read access should be free of any exclusive locks.
  */
 static void ccids_write_lock(void)
 {
         spin_lock(&ccids_lock);
         while (atomic_read(&ccids_lockct) != 0) {
                 spin_unlock(&ccids_lock);
                 yield();
                 spin_lock(&ccids_lock);
         }
 }
 
 static inline void ccids_write_unlock(void)
 {
         spin_unlock(&ccids_lock);
 }
 
 static inline void ccids_read_lock(void)
 {
         atomic_inc(&ccids_lockct);
         smp_mb__after_atomic_inc();
         spin_unlock_wait(&ccids_lock);
 }
 
 static inline void ccids_read_unlock(void)
 {
         atomic_dec(&ccids_lockct);
 }
 
 #else
 #define ccids_write_lock() do { } while(0)
 #define ccids_write_unlock() do { } while(0)
 #define ccids_read_lock() do { } while(0)
 #define ccids_read_unlock() do { } while(0)
 #endif
 
 static struct kmem_cache *ccid_kmem_cache_create(int obj_size, const char *fmt,...)
 {
         struct kmem_cache *slab;
         char slab_name_fmt[32], *slab_name;
         va_list args;
 
         va_start(args, fmt);
         vsnprintf(slab_name_fmt, sizeof(slab_name_fmt), fmt, args);
         va_end(args);
 
         slab_name = kstrdup(slab_name_fmt, GFP_KERNEL);
         if (slab_name == NULL)
                 return NULL;
         slab = kmem_cache_create(slab_name, sizeof(struct ccid) + obj_size, 0,
                                  SLAB_HWCACHE_ALIGN, NULL);
         if (slab == NULL)
                 kfree(slab_name);
         return slab;
 }
 
 static void ccid_kmem_cache_destroy(struct kmem_cache *slab)
 {
         if (slab != NULL) {
                 const char *name = kmem_cache_name(slab);
 
                 kmem_cache_destroy(slab);
                 kfree(name);
         }
 }
 
 int ccid_register(struct ccid_operations *ccid_ops)
 {
         int err = -ENOBUFS;
 
         ccid_ops->ccid_hc_rx_slab =
                         ccid_kmem_cache_create(ccid_ops->ccid_hc_rx_obj_size,
                                                "ccid%u_hc_rx_sock",
                                                ccid_ops->ccid_id);
         if (ccid_ops->ccid_hc_rx_slab == NULL)
                 goto out;
 
        ccid_ops->ccid_hc_tx_slab =
                        ccid_kmem_cache_create(ccid_ops->ccid_hc_tx_obj_size,
                                               "ccid%u_hc_tx_sock",
                                               ccid_ops->ccid_id);
        if (ccid_ops->ccid_hc_tx_slab == NULL)
                goto out_free_rx_slab;

        ccids_write_lock();
        err = -EEXIST;
        if (ccids[ccid_ops->ccid_id] == NULL) {
                ccids[ccid_ops->ccid_id] = ccid_ops;
                err = 0;
        }
        ccids_write_unlock();
        if (err != 0)
                goto out_free_tx_slab;

        pr_info("CCID: Registered CCID %d (%s)\n",
                ccid_ops->ccid_id, ccid_ops->ccid_name);
out:
        return err;
out_free_tx_slab:
        ccid_kmem_cache_destroy(ccid_ops->ccid_hc_tx_slab);
        ccid_ops->ccid_hc_tx_slab = NULL;
        goto out;
out_free_rx_slab:
        ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
        ccid_ops->ccid_hc_rx_slab = NULL;
        goto out;
}

EXPORT_SYMBOL_GPL(ccid_register);

int ccid_unregister(struct ccid_operations *ccid_ops)
{
        ccids_write_lock();
        ccids[ccid_ops->ccid_id] = NULL;
        ccids_write_unlock();

        ccid_kmem_cache_destroy(ccid_ops->ccid_hc_tx_slab);
        ccid_ops->ccid_hc_tx_slab = NULL;
        ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
        ccid_ops->ccid_hc_rx_slab = NULL;

        pr_info("CCID: Unregistered CCID %d (%s)\n",
                ccid_ops->ccid_id, ccid_ops->ccid_name);
        return 0;
}

EXPORT_SYMBOL_GPL(ccid_unregister);

struct ccid *ccid_new(unsigned char id, struct sock *sk, int rx, gfp_t gfp)
{
        struct ccid_operations *ccid_ops;
        struct ccid *ccid = NULL;

        ccids_read_lock();
#ifdef CONFIG_MODULES
        if (ccids[id] == NULL) {
                /* We only try to load if in process context */
                ccids_read_unlock();
                if (gfp & GFP_ATOMIC)
                        goto out;
                request_module("net-dccp-ccid-%d", id);
                ccids_read_lock();
        }
#endif
        ccid_ops = ccids[id];
        if (ccid_ops == NULL)
                goto out_unlock;

        if (!try_module_get(ccid_ops->ccid_owner))
                goto out_unlock;

        ccids_read_unlock();

        ccid = kmem_cache_alloc(rx ? ccid_ops->ccid_hc_rx_slab :
                                     ccid_ops->ccid_hc_tx_slab, gfp);
        if (ccid == NULL)
                goto out_module_put;
        ccid->ccid_ops = ccid_ops;
        if (rx) {
                memset(ccid + 1, 0, ccid_ops->ccid_hc_rx_obj_size);
                if (ccid->ccid_ops->ccid_hc_rx_init != NULL &&
                    ccid->ccid_ops->ccid_hc_rx_init(ccid, sk) != 0)
                        goto out_free_ccid;
        } else {
                memset(ccid + 1, 0, ccid_ops->ccid_hc_tx_obj_size);
                if (ccid->ccid_ops->ccid_hc_tx_init != NULL &&
                    ccid->ccid_ops->ccid_hc_tx_init(ccid, sk) != 0)
                        goto out_free_ccid;
        }
out:
        return ccid;
out_unlock:
        ccids_read_unlock();
        goto out;
out_free_ccid:
        kmem_cache_free(rx ? ccid_ops->ccid_hc_rx_slab :
                        ccid_ops->ccid_hc_tx_slab, ccid);
        ccid = NULL;
out_module_put:
        module_put(ccid_ops->ccid_owner);
        goto out;
}

EXPORT_SYMBOL_GPL(ccid_new);

struct ccid *ccid_hc_rx_new(unsigned char id, struct sock *sk, gfp_t gfp)
{
        return ccid_new(id, sk, 1, gfp);
}

EXPORT_SYMBOL_GPL(ccid_hc_rx_new);

struct ccid *ccid_hc_tx_new(unsigned char id,struct sock *sk,  gfp_t gfp)
{
        return ccid_new(id, sk, 0, gfp);
}

EXPORT_SYMBOL_GPL(ccid_hc_tx_new);

static void ccid_delete(struct ccid *ccid, struct sock *sk, int rx)
{
        struct ccid_operations *ccid_ops;

        if (ccid == NULL)
                return;

        ccid_ops = ccid->ccid_ops;
        if (rx) {
                if (ccid_ops->ccid_hc_rx_exit != NULL)
                        ccid_ops->ccid_hc_rx_exit(sk);
                kmem_cache_free(ccid_ops->ccid_hc_rx_slab,  ccid);
        } else {
                if (ccid_ops->ccid_hc_tx_exit != NULL)
                        ccid_ops->ccid_hc_tx_exit(sk);
                kmem_cache_free(ccid_ops->ccid_hc_tx_slab,  ccid);
        }
        ccids_read_lock();
        if (ccids[ccid_ops->ccid_id] != NULL)
                module_put(ccid_ops->ccid_owner);
        ccids_read_unlock();
}

void ccid_hc_rx_delete(struct ccid *ccid, struct sock *sk)
{
        ccid_delete(ccid, sk, 1);
}

EXPORT_SYMBOL_GPL(ccid_hc_rx_delete);

void ccid_hc_tx_delete(struct ccid *ccid, struct sock *sk)
{
        ccid_delete(ccid, sk, 0);
}

EXPORT_SYMBOL_GPL(ccid_hc_tx_delete);