ISDN: Make PPP compressors unload-safe.

Remove MOD_{INC,DEC}_USE_COUNT and introduce .owner instead.

drivers/isdn/i4l/isdn_bsdcomp.c

@@ -300,7 +300,6 @@ static void bsd_free (void *state)
 		 * Finally release the structure itself.
 		 */
 		kfree (db);
-		MOD_DEC_USE_COUNT;
 	}
 }
 
@@ -355,8 +354,6 @@ static void *bsd_alloc (struct isdn_ppp_comp_data *data)
 		return NULL;
 	}
 
-	MOD_INC_USE_COUNT;
-
 	/*
 	 * If this is the compression buffer then there is no length data.
 	 * For decompression, the length information is needed as well.
@@ -907,6 +904,7 @@ static int bsd_decompress (void *state, struct sk_buff *skb_in, struct sk_buff *
  *************************************************************/
 
 static struct isdn_ppp_compressor ippp_bsd_compress = {
+	.owner          = THIS_MODULE,
 	.num            = CI_BSD_COMPRESS,
 	.alloc          = bsd_alloc,
 	.free           = bsd_free,

drivers/isdn/i4l/isdn_ppp_ccp.c

@@ -259,11 +259,14 @@ ippp_ccp_free(struct ippp_ccp *ccp)
 {
 	int id;
 
-	if (ccp->comp_stat)
+	if (ccp->comp_stat) {
 		ccp->compressor->free(ccp->comp_stat);
-	if (ccp->decomp_stat)
+		module_put(ccp->compressor->owner);
+	}
+	if (ccp->decomp_stat) {
 		ccp->decompressor->free(ccp->decomp_stat);
-
+		module_put(ccp->decompressor->owner);
+	}
 	for (id = 0; id < 256; id++) {
 		if (ccp->reset->rs[id])
 			ippp_ccp_reset_free_state(ccp, id);
@@ -572,25 +575,34 @@ ippp_ccp_set_compressor(struct ippp_ccp *ccp, int unit,
 		if (ipc->num != num)
 			continue;
 		
+		if (!try_module_get(ipc->owner))
+			continue;
+
 		stat = ipc->alloc(data);
 		if (!stat) {
 			printk(KERN_ERR "Can't alloc (de)compression!\n");
+			module_put(ipc->owner);
 			break;
 		}
 		ret = ipc->init(stat, data, unit, 0);
 		if(!ret) {
 			printk(KERN_ERR "Can't init (de)compression!\n");
 			ipc->free(stat);
+			module_put(ipc->owner);
 			break;
 		}
 		if (data->flags & IPPP_COMP_FLAG_XMIT) {
-			if (ccp->comp_stat)
+			if (ccp->comp_stat) {
 				ccp->compressor->free(ccp->comp_stat);
+				module_put(ccp->compressor->owner);
+			}
 			ccp->comp_stat = stat;
 			ccp->compressor = ipc;
 		} else {
-			if (ccp->decomp_stat)
+			if (ccp->decomp_stat) {
 				ccp->decompressor->free(ccp->decomp_stat);
+				module_put(ccp->decompressor->owner);
+			}
 			ccp->decomp_stat = stat;
 			ccp->decompressor = ipc;
 		}

include/linux/isdn_ppp.h

@@ -95,6 +95,7 @@ struct isdn_ppp_resetparams {
  * check the original include for more information
  */
 struct isdn_ppp_compressor {
+	struct module *owner;
 	struct isdn_ppp_compressor *next, *prev;
 	int num; /* CCP compression protocol number */