[DCCP] CCID: Improve CCID infrastructure

1. No need for ->ccid_init nor ->ccid_exit, this is what module_{init,exit}
   does and anynways neither ccid2 nor ccid3 were using it.

2. Rename struct ccid to struct ccid_operations and introduce struct ccid
   with a pointer to ccid_operations and rigth after it the rx or tx
   private state.

3. Remove the pointer to the state of the half connections from struct
   dccp_sock, now its derived thru ccid_priv() from the ccid pointer.

Now we also can implement the setsockopt for changing the CCID easily as
no ccid init routines can affect struct dccp_sock in any way that prevents
other CCIDs from working if a CCID switch operation is asked by apps.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 154 insertions, 34 deletions

diff --git a/net/dccp/ccid.c b/net/dccp/ccid.c
index 06b191a5740b..ff05e59043cd 100644
--- a/net/dccp/ccid.c
+++ b/net/dccp/ccid.c
@@ -13,7 +13,7 @@
 
 #include "ccid.h"
 
-static struct ccid *ccids[CCID_MAX];
+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);
@@ -55,82 +55,202 @@ static inline void ccids_read_unlock(void)
 #define ccids_read_unlock() do { } while(0)
 #endif
 
-int ccid_register(struct ccid *ccid)
+static kmem_cache_t *ccid_kmem_cache_create(int obj_size, const char *fmt,...)
 {
-        int err;
+        kmem_cache_t *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, NULL);
+        if (slab == NULL)
+                kfree(slab_name);
+        return slab;
+}
+
+static void ccid_kmem_cache_destroy(kmem_cache_t *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,
+                                               "%s_hc_rx_sock",
+                                               ccid_ops->ccid_name);
+        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,
+                                               "%s_hc_tx_sock",
+                                               ccid_ops->ccid_name);
+        if (ccid_ops->ccid_hc_tx_slab == NULL)
+                goto out_free_rx_slab;
 
         ccids_write_lock();
         err = -EEXIST;
-        if (ccids[ccid->ccid_id] == NULL) {
-                ccids[ccid->ccid_id] = ccid;
+        if (ccids[ccid_ops->ccid_id] == NULL) {
+                ccids[ccid_ops->ccid_id] = ccid_ops;
                 err = 0;
         }
         ccids_write_unlock();
-        if (err == 0)
-                pr_info("CCID: Registered CCID %d (%s)\n",
-                        ccid->ccid_id, ccid->ccid_name);
+        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 *ccid)
+int ccid_unregister(struct ccid_operations *ccid_ops)
 {
         ccids_write_lock();
-        ccids[ccid->ccid_id] = NULL;
+        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->ccid_id, ccid->ccid_name);
+                ccid_ops->ccid_id, ccid_ops->ccid_name);
         return 0;
 }
 
 EXPORT_SYMBOL_GPL(ccid_unregister);
 
-struct ccid *ccid_init(unsigned char id, struct sock *sk)
+struct ccid *ccid_new(unsigned char id, struct sock *sk, int rx, gfp_t gfp)
 {
-        struct ccid *ccid;
+        struct ccid_operations *ccid_ops;
+        struct ccid *ccid = NULL;
 
+        ccids_read_lock();
 #ifdef CONFIG_KMOD
-        if (ccids[id] == NULL)
+        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
-        ccids_read_lock();
+        ccid_ops = ccids[id];
+        if (ccid_ops == NULL)
+                goto out_unlock;
 
-        ccid = ccids[id];
-        if (ccid == NULL)
-                goto out;
+        if (!try_module_get(ccid_ops->ccid_owner))
+                goto out_unlock;
 
-        if (!try_module_get(ccid->ccid_owner))
-                goto out_err;
+        ccids_read_unlock();
 
-        if (ccid->ccid_init != NULL && ccid->ccid_init(sk) != 0)
+        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:
-        ccids_read_unlock();
         return ccid;
-out_module_put:
-        module_put(ccid->ccid_owner);
-out_err:
+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_init);
+EXPORT_SYMBOL_GPL(ccid_new);
 
-void ccid_exit(struct ccid *ccid, struct sock *sk)
+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();
+}
 
-        if (ccids[ccid->ccid_id] != NULL) {
-                if (ccid->ccid_exit != NULL)
-                        ccid->ccid_exit(sk);
-                module_put(ccid->ccid_owner);
-        }
+void ccid_hc_rx_delete(struct ccid *ccid, struct sock *sk)
+{
+        ccid_delete(ccid, sk, 1);
+}
 
-        ccids_read_unlock();
+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_exit);
+EXPORT_SYMBOL_GPL(ccid_hc_tx_delete);