linux/net/9p/mod.c
Thomas Weißschuh 019641d1b5 net/p9: load default transports
Now that all transports are split into modules it may happen that no
transports are registered when v9fs_get_default_trans() is called.
When that is the case try to load more transports from modules.

Link: https://lkml.kernel.org/r/20211103193823.111007-5-linux@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
[Dominique: constify v9fs_get_trans_by_name argument as per patch1v2]
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
2022-01-10 10:00:09 +09:00

213 lines
4.3 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* 9P entry point
*
* Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
* Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/moduleparam.h>
#include <net/9p/9p.h>
#include <linux/fs.h>
#include <linux/parser.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#ifdef CONFIG_NET_9P_DEBUG
unsigned int p9_debug_level; /* feature-rific global debug level */
EXPORT_SYMBOL(p9_debug_level);
module_param_named(debug, p9_debug_level, uint, 0);
MODULE_PARM_DESC(debug, "9P debugging level");
void _p9_debug(enum p9_debug_flags level, const char *func,
const char *fmt, ...)
{
struct va_format vaf;
va_list args;
if ((p9_debug_level & level) != level)
return;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
if (level == P9_DEBUG_9P)
pr_notice("(%8.8d) %pV", task_pid_nr(current), &vaf);
else
pr_notice("-- %s (%d): %pV", func, task_pid_nr(current), &vaf);
va_end(args);
}
EXPORT_SYMBOL(_p9_debug);
#endif
/* Dynamic Transport Registration Routines */
static DEFINE_SPINLOCK(v9fs_trans_lock);
static LIST_HEAD(v9fs_trans_list);
/**
* v9fs_register_trans - register a new transport with 9p
* @m: structure describing the transport module and entry points
*
*/
void v9fs_register_trans(struct p9_trans_module *m)
{
spin_lock(&v9fs_trans_lock);
list_add_tail(&m->list, &v9fs_trans_list);
spin_unlock(&v9fs_trans_lock);
}
EXPORT_SYMBOL(v9fs_register_trans);
/**
* 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);
static struct p9_trans_module *_p9_get_trans_by_name(const char *s)
{
struct p9_trans_module *t, *found = NULL;
spin_lock(&v9fs_trans_lock);
list_for_each_entry(t, &v9fs_trans_list, list)
if (strcmp(t->name, s) == 0 &&
try_module_get(t->owner)) {
found = t;
break;
}
spin_unlock(&v9fs_trans_lock);
return found;
}
/**
* v9fs_get_trans_by_name - get transport with the matching name
* @s: string identifying transport
*
*/
struct p9_trans_module *v9fs_get_trans_by_name(const char *s)
{
struct p9_trans_module *found = NULL;
found = _p9_get_trans_by_name(s);
#ifdef CONFIG_MODULES
if (!found) {
request_module("9p-%s", s);
found = _p9_get_trans_by_name(s);
}
#endif
return found;
}
EXPORT_SYMBOL(v9fs_get_trans_by_name);
static const char * const v9fs_default_transports[] = {
"virtio", "tcp", "fd", "unix", "xen", "rdma",
};
/**
* v9fs_get_default_trans - get the default transport
*
*/
struct p9_trans_module *v9fs_get_default_trans(void)
{
struct p9_trans_module *t, *found = NULL;
int i;
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);
for (i = 0; !found && i < ARRAY_SIZE(v9fs_default_transports); i++)
found = v9fs_get_trans_by_name(v9fs_default_transports[i]);
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);
}
/**
* init_p9 - Initialize module
*
*/
static int __init init_p9(void)
{
int ret;
ret = p9_client_init();
if (ret)
return ret;
p9_error_init();
pr_info("Installing 9P2000 support\n");
return ret;
}
/**
* exit_p9 - shutdown module
*
*/
static void __exit exit_p9(void)
{
pr_info("Unloading 9P2000 support\n");
p9_client_exit();
}
module_init(init_p9)
module_exit(exit_p9)
MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Plan 9 Resource Sharing Support (9P2000)");