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
......@@ -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 */
......@@ -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 */
......@@ -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);
......
......@@ -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;
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;
}
return NULL;
struct p9_trans_module *t, *found = NULL;
spin_lock(&v9fs_trans_lock);
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;
}
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;
}
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_default_trans);
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)
......
......@@ -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);
}
......@@ -528,6 +528,7 @@ static struct p9_trans_module p9_virtio_trans = {
.create = p9_virtio_create,
.maxsize = PAGE_SIZE*16,
.def = 0,
.owner = THIS_MODULE,
};
/* The standard init function */
......@@ -545,6 +546,7 @@ static int __init p9_virtio_init(void)
static void __exit p9_virtio_cleanup(void)
{
unregister_virtio_driver(&p9_virtio_drv);
v9fs_unregister_trans(&p9_virtio_trans);
}
module_init(p9_virtio_init);
......
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