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5adb5bc65f
Right now there's nothing to stop the various paths that use rs->rs_transport from racing with rmmod and executing freed transport code. The simple fix is to have binding to a transport also hold a reference to the transport's module, removing this class of races. We already had an unused t_owner field which was set for the modular transports and which wasn't set for the built-in loop transport. Signed-off-by: Zach Brown <zach.brown@oracle.com>
138 lines
3.6 KiB
C
138 lines
3.6 KiB
C
/*
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* Copyright (c) 2006 Oracle. All rights reserved.
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*
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* This software is available to you under a choice of one of two
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* licenses. You may choose to be licensed under the terms of the GNU
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* General Public License (GPL) Version 2, available from the file
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* COPYING in the main directory of this source tree, or the
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* OpenIB.org BSD license below:
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*
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* Redistribution and use in source and binary forms, with or
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* without modification, are permitted provided that the following
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* conditions are met:
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*
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* - Redistributions of source code must retain the above
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* copyright notice, this list of conditions and the following
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* disclaimer.
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*
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* - Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials
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* provided with the distribution.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/in.h>
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#include "rds.h"
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#include "loop.h"
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static struct rds_transport *transports[RDS_TRANS_COUNT];
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static DECLARE_RWSEM(rds_trans_sem);
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int rds_trans_register(struct rds_transport *trans)
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{
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BUG_ON(strlen(trans->t_name) + 1 > TRANSNAMSIZ);
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down_write(&rds_trans_sem);
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if (transports[trans->t_type])
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printk(KERN_ERR "RDS Transport type %d already registered\n",
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trans->t_type);
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else {
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transports[trans->t_type] = trans;
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printk(KERN_INFO "Registered RDS/%s transport\n", trans->t_name);
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}
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up_write(&rds_trans_sem);
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return 0;
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}
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EXPORT_SYMBOL_GPL(rds_trans_register);
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void rds_trans_unregister(struct rds_transport *trans)
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{
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down_write(&rds_trans_sem);
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transports[trans->t_type] = NULL;
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printk(KERN_INFO "Unregistered RDS/%s transport\n", trans->t_name);
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up_write(&rds_trans_sem);
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}
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EXPORT_SYMBOL_GPL(rds_trans_unregister);
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void rds_trans_put(struct rds_transport *trans)
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{
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if (trans && trans->t_owner)
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module_put(trans->t_owner);
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}
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struct rds_transport *rds_trans_get_preferred(__be32 addr)
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{
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struct rds_transport *ret = NULL;
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struct rds_transport *trans;
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unsigned int i;
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if (IN_LOOPBACK(ntohl(addr)))
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return &rds_loop_transport;
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down_read(&rds_trans_sem);
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for (i = 0; i < RDS_TRANS_COUNT; i++) {
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trans = transports[i];
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if (trans && (trans->laddr_check(addr) == 0) &&
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(!trans->t_owner || try_module_get(trans->t_owner))) {
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ret = trans;
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break;
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}
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}
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up_read(&rds_trans_sem);
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return ret;
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}
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/*
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* This returns the number of stats entries in the snapshot and only
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* copies them using the iter if there is enough space for them. The
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* caller passes in the global stats so that we can size and copy while
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* holding the lock.
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*/
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unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
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unsigned int avail)
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{
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struct rds_transport *trans;
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unsigned int total = 0;
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unsigned int part;
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int i;
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rds_info_iter_unmap(iter);
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down_read(&rds_trans_sem);
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for (i = 0; i < RDS_TRANS_COUNT; i++)
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{
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trans = transports[i];
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if (!trans || !trans->stats_info_copy)
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continue;
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part = trans->stats_info_copy(iter, avail);
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avail -= min(avail, part);
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total += part;
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}
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up_read(&rds_trans_sem);
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return total;
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}
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