[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 06b191a..ff05e59 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);