From: Tejun Heo Date: Wed, 24 Sep 2008 21:22:23 +0000 (-0500) Subject: 9p: implement proper trans module refcounting and unregistration X-Git-Tag: v2.6.27-rc8~25^2~7 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=72029fe85d8d060b3f966f2dbc36b3c75b5a6532;p=linux-2.6-omap-h63xx.git 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: Tejun Heo Signed-off-by: Eric Van Hensbergen --- diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h index b3d3e27c629..c3626c0ba9d 100644 --- a/include/net/9p/9p.h +++ b/include/net/9p/9p.h @@ -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 */ diff --git a/include/net/9p/transport.h b/include/net/9p/transport.h index 0db3a4038dc..3ca737120a9 100644 --- a/include/net/9p/transport.h +++ b/include/net/9p/transport.h @@ -26,6 +26,8 @@ #ifndef NET_9P_TRANSPORT_H #define NET_9P_TRANSPORT_H +#include + /** * 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 */ diff --git a/net/9p/client.c b/net/9p/client.c index 2ffe40cf2f0..10e320307ec 100644 --- a/net/9p/client.c +++ b/net/9p/client.c @@ -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); diff --git a/net/9p/mod.c b/net/9p/mod.c index bdee1fb7cc6..1084feb24cb 100644 --- a/net/9p/mod.c +++ b/net/9p/mod.c @@ -31,6 +31,7 @@ #include #include #include +#include #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) diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index cdf137af7ad..6a32ffdb942 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -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); +} diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 42adc052b14..94912e077a5 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -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);