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Commit 72029fe8 authored by Tejun Heo's avatar Tejun Heo Committed by Eric Van Hensbergen
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9p: implement proper trans module refcounting and unregistration 



9p trans modules aren't refcounted nor were they unregistered
properly.  Fix it.

* Add 9p_trans_module->owner and reference the module on each trans
  instance creation and put it on destruction.

* Protect v9fs_trans_list with a spinlock.  This isn't strictly
  necessary as the list is manipulated only during module loading /
  unloading but it's a good idea to make the API safe.

* Unregister trans modules when the corresponding module is being
  unloaded.

* While at it, kill unnecessary EXPORT_SYMBOL on p9_trans_fd_init().

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarEric Van Hensbergen <ericvh@gmail.com>
parent 72d31053

include/net/9p/9p.h

+1 −0
Original line number Diff line number Diff line
@@ -596,4 +596,5 @@ int p9_idpool_check(int id, struct p9_idpool *p); 
int p9_error_init(void);

int p9_errstr2errno(char *, int);

int p9_trans_fd_init(void);

void p9_trans_fd_exit(void);

#endif /* NET_9P_H */

include/net/9p/transport.h

+7 −2
Original line number Diff line number Diff line
@@ -26,6 +26,8 @@ 
#ifndef NET_9P_TRANSPORT_H

#define NET_9P_TRANSPORT_H



#include <linux/module.h>



/**

 * enum p9_trans_status - different states of underlying transports

 * @Connected: transport is connected and healthy
@@ -91,9 +93,12 @@ struct p9_trans_module { 
	int maxsize;		/* max message size of transport */

	int def;		/* this transport should be default */

	struct p9_trans * (*create)(const char *, char *, int, unsigned char);

	struct module *owner;

};



void v9fs_register_trans(struct p9_trans_module *m);

struct p9_trans_module *v9fs_match_trans(const substring_t *name);

struct p9_trans_module *v9fs_default_trans(void);

void v9fs_unregister_trans(struct p9_trans_module *m);

struct p9_trans_module *v9fs_get_trans_by_name(const substring_t *name);

struct p9_trans_module *v9fs_get_default_trans(void);

void v9fs_put_trans(struct p9_trans_module *m);

#endif /* NET_9P_TRANSPORT_H */

net/9p/client.c

+8 −2
Original line number Diff line number Diff line
@@ -75,7 +75,6 @@ static int parse_opts(char *opts, struct p9_client *clnt) 
	int option;

	int ret = 0;



	clnt->trans_mod = v9fs_default_trans();

	clnt->dotu = 1;

	clnt->msize = 8192;
@@ -108,7 +107,7 @@ static int parse_opts(char *opts, struct p9_client *clnt) 
			clnt->msize = option;

			break;

		case Opt_trans:

			clnt->trans_mod = v9fs_match_trans(&args[0]);

			clnt->trans_mod = v9fs_get_trans_by_name(&args[0]);

			break;

		case Opt_legacy:

			clnt->dotu = 0;
@@ -117,6 +116,10 @@ static int parse_opts(char *opts, struct p9_client *clnt) 
			continue;

		}

	}



	if (!clnt->trans_mod)

		clnt->trans_mod = v9fs_get_default_trans();



	kfree(options);

	return ret;

}
@@ -150,6 +153,7 @@ struct p9_client *p9_client_create(const char *dev_name, char *options) 
	if (!clnt)

		return ERR_PTR(-ENOMEM);



	clnt->trans_mod = NULL;

	clnt->trans = NULL;

	spin_lock_init(&clnt->lock);

	INIT_LIST_HEAD(&clnt->fidlist);
@@ -235,6 +239,8 @@ void p9_client_destroy(struct p9_client *clnt) 
		clnt->trans = NULL;

	}



	v9fs_put_trans(clnt->trans_mod);



	list_for_each_entry_safe(fid, fidptr, &clnt->fidlist, flist)

		p9_fid_destroy(fid);

net/9p/mod.c

+67 −25
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <linux/parser.h>

#include <net/9p/transport.h>

#include <linux/list.h>

#include <linux/spinlock.h>



#ifdef CONFIG_NET_9P_DEBUG

unsigned int p9_debug_level = 0;	/* feature-rific global debug level  */
@@ -44,8 +45,8 @@ MODULE_PARM_DESC(debug, "9P debugging level"); 
 *

 */



static DEFINE_SPINLOCK(v9fs_trans_lock);

static LIST_HEAD(v9fs_trans_list);

static struct p9_trans_module *v9fs_default_transport;



/**

 * v9fs_register_trans - register a new transport with 9p
@@ -54,48 +55,87 @@ static struct p9_trans_module *v9fs_default_transport; 
 */

void v9fs_register_trans(struct p9_trans_module *m)

{

	spin_lock(&v9fs_trans_lock);

	list_add_tail(&m->list, &v9fs_trans_list);

	if (m->def)

		v9fs_default_transport = m;

	spin_unlock(&v9fs_trans_lock);

}

EXPORT_SYMBOL(v9fs_register_trans);



/**

 * v9fs_match_trans - match transport versus registered transports

 * v9fs_unregister_trans - unregister a 9p transport

 * @m: the transport to remove

 *

 */

void v9fs_unregister_trans(struct p9_trans_module *m)

{

	spin_lock(&v9fs_trans_lock);

	list_del_init(&m->list);

	spin_unlock(&v9fs_trans_lock);

}

EXPORT_SYMBOL(v9fs_unregister_trans);



/**

 * v9fs_get_trans_by_name - get transport with the matching name

 * @name: string identifying transport

 *

 */

struct p9_trans_module *v9fs_match_trans(const substring_t *name)

struct p9_trans_module *v9fs_get_trans_by_name(const substring_t *name)

{

	struct list_head *p;

	struct p9_trans_module *t = NULL;

	struct p9_trans_module *t, *found = NULL;



	spin_lock(&v9fs_trans_lock);



	list_for_each(p, &v9fs_trans_list) {

		t = list_entry(p, struct p9_trans_module, list);

		if (strncmp(t->name, name->from, name->to-name->from) == 0)

			return t;

	list_for_each_entry(t, &v9fs_trans_list, list)

		if (strncmp(t->name, name->from, name->to-name->from) == 0 &&

		    try_module_get(t->owner)) {

			found = t;

			break;

		}

	return NULL;



	spin_unlock(&v9fs_trans_lock);

	return found;

}

EXPORT_SYMBOL(v9fs_match_trans);

EXPORT_SYMBOL(v9fs_get_trans_by_name);



/**

 * v9fs_default_trans - returns pointer to default transport

 * v9fs_get_default_trans - get the default transport

 *

 */



struct p9_trans_module *v9fs_default_trans(void)

struct p9_trans_module *v9fs_get_default_trans(void)

{

	if (v9fs_default_transport)

		return v9fs_default_transport;

	else if (!list_empty(&v9fs_trans_list))

		return list_first_entry(&v9fs_trans_list,

					struct p9_trans_module, list);

	else

		return NULL;

	struct p9_trans_module *t, *found = NULL;



	spin_lock(&v9fs_trans_lock);



	list_for_each_entry(t, &v9fs_trans_list, list)

		if (t->def && try_module_get(t->owner)) {

			found = t;

			break;

		}

EXPORT_SYMBOL(v9fs_default_trans);



	if (!found)

		list_for_each_entry(t, &v9fs_trans_list, list)

			if (try_module_get(t->owner)) {

				found = t;

				break;

			}



	spin_unlock(&v9fs_trans_lock);

	return found;

}

EXPORT_SYMBOL(v9fs_get_default_trans);



/**

 * v9fs_put_trans - put trans

 * @m: transport to put

 *

 */

void v9fs_put_trans(struct p9_trans_module *m)

{

	if (m)

		module_put(m->owner);

}



/**

 * v9fs_init - Initialize module
@@ -120,6 +160,8 @@ static int __init init_p9(void) 
static void __exit exit_p9(void)

{

	printk(KERN_INFO "Unloading 9P2000 support\n");



	p9_trans_fd_exit();

}



module_init(init_p9)

net/9p/trans_fd.c

+10 −1
Original line number Diff line number Diff line
@@ -1629,6 +1629,7 @@ static struct p9_trans_module p9_tcp_trans = { 
	.maxsize = MAX_SOCK_BUF,

	.def = 1,

	.create = p9_trans_create_tcp,

	.owner = THIS_MODULE,

};



static struct p9_trans_module p9_unix_trans = {
@@ -1636,6 +1637,7 @@ static struct p9_trans_module p9_unix_trans = { 
	.maxsize = MAX_SOCK_BUF,

	.def = 0,

	.create = p9_trans_create_unix,

	.owner = THIS_MODULE,

};



static struct p9_trans_module p9_fd_trans = {
@@ -1643,6 +1645,7 @@ static struct p9_trans_module p9_fd_trans = { 
	.maxsize = MAX_SOCK_BUF,

	.def = 0,

	.create = p9_trans_create_fd,

	.owner = THIS_MODULE,

};



int p9_trans_fd_init(void)
@@ -1659,4 +1662,10 @@ int p9_trans_fd_init(void) 


	return 0;

}

EXPORT_SYMBOL(p9_trans_fd_init);
 


void p9_trans_fd_exit(void)

{

	v9fs_unregister_trans(&p9_tcp_trans);

	v9fs_unregister_trans(&p9_unix_trans);

	v9fs_unregister_trans(&p9_fd_trans);

}