/* * Copyright (c) 2006 Oracle. All rights reserved. * * This software is available to you under a choice of one of two * licenses. You may choose to be licensed under the terms of the GNU * General Public License (GPL) Version 2, available from the file * COPYING in the main directory of this source tree, or the * OpenIB.org BSD license below: * * Redistribution and use in source and binary forms, with or * without modification, are permitted provided that the following * conditions are met: * * - Redistributions of source code must retain the above * copyright notice, this list of conditions and the following * disclaimer. * * - Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials * provided with the distribution. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. * */ #include #include #include #include "rds.h" #include "loop.h" static struct rds_transport *transports[RDS_TRANS_COUNT]; static DECLARE_RWSEM(rds_trans_sem); int rds_trans_register(struct rds_transport *trans) { BUG_ON(strlen(trans->t_name) + 1 > TRANSNAMSIZ); down_write(&rds_trans_sem); if (transports[trans->t_type]) printk(KERN_ERR "RDS Transport type %d already registered\n", trans->t_type); else { transports[trans->t_type] = trans; printk(KERN_INFO "Registered RDS/%s transport\n", trans->t_name); } up_write(&rds_trans_sem); return 0; } EXPORT_SYMBOL_GPL(rds_trans_register); void rds_trans_unregister(struct rds_transport *trans) { down_write(&rds_trans_sem); transports[trans->t_type] = NULL; printk(KERN_INFO "Unregistered RDS/%s transport\n", trans->t_name); up_write(&rds_trans_sem); } EXPORT_SYMBOL_GPL(rds_trans_unregister); void rds_trans_put(struct rds_transport *trans) { if (trans) module_put(trans->t_owner); } struct rds_transport *rds_trans_get_preferred(struct net *net, __be32 addr) { struct rds_transport *ret = NULL; struct rds_transport *trans; unsigned int i; if (IN_LOOPBACK(ntohl(addr))) return &rds_loop_transport; down_read(&rds_trans_sem); for (i = 0; i < RDS_TRANS_COUNT; i++) { trans = transports[i]; if (trans && (trans->laddr_check(net, addr) == 0) && (!trans->t_owner || try_module_get(trans->t_owner))) { ret = trans; break; } } up_read(&rds_trans_sem); return ret; } struct rds_transport *rds_trans_get(int t_type) { struct rds_transport *ret = NULL; struct rds_transport *trans; unsigned int i; down_read(&rds_trans_sem); for (i = 0; i < RDS_TRANS_COUNT; i++) { trans = transports[i]; if (trans && trans->t_type == t_type && (!trans->t_owner || try_module_get(trans->t_owner))) { ret = trans; break; } } up_read(&rds_trans_sem); return ret; } /* * This returns the number of stats entries in the snapshot and only * copies them using the iter if there is enough space for them. The * caller passes in the global stats so that we can size and copy while * holding the lock. */ unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter, unsigned int avail) { struct rds_transport *trans; unsigned int total = 0; unsigned int part; int i; rds_info_iter_unmap(iter); down_read(&rds_trans_sem); for (i = 0; i < RDS_TRANS_COUNT; i++) { trans = transports[i]; if (!trans || !trans->stats_info_copy) continue; part = trans->stats_info_copy(iter, avail); avail -= min(avail, part); total += part; } up_read(&rds_trans_sem); return total; } mode:
authorIago Abal <mail@iagoabal.eu>2017-01-11 14:00:21 +0100
committerVinod Koul <vinod.koul@intel.com>2017-01-25 15:35:11 +0530
commit91539eb1fda2d530d3b268eef542c5414e54bf1a (patch)
tree960f5ca6342ad20837aff18aad6e8ecd7da32fd6 /fs/xfs/xfs_trans_ail.c
parent6610d0edf6dc7ee97e46ab3a538a565c79d26199 (diff)
dmaengine: pl330: fix double lock
The static bug finder EBA (http://www.iagoabal.eu/eba/) reported the following double-lock bug: Double lock: 1. spin_lock_irqsave(pch->lock, flags) at pl330_free_chan_resources:2236; 2. call to function `pl330_release_channel' immediately after; 3. call to function `dma_pl330_rqcb' in line 1753; 4. spin_lock_irqsave(pch->lock, flags) at dma_pl330_rqcb:1505. I have fixed it as suggested by Marek Szyprowski. First, I have replaced `pch->lock' with `pl330->lock' in functions `pl330_alloc_chan_resources' and `pl330_free_chan_resources'. This avoids the double-lock by acquiring a different lock than `dma_pl330_rqcb'. NOTE that, as a result, `pl330_free_chan_resources' executes `list_splice_tail_init' on `pch->work_list' under lock `pl330->lock', whereas in the rest of the code `pch->work_list' is protected by `pch->lock'. I don't know if this may cause race conditions. Similarly `pch->cyclic' is written by `pl330_alloc_chan_resources' under `pl330->lock' but read by `pl330_tx_submit' under `pch->lock'. Second, I have removed locking from `pl330_request_channel' and `pl330_release_channel' functions. Function `pl330_request_channel' is only called from `pl330_alloc_chan_resources', so the lock is already held. Function `pl330_release_channel' is called from `pl330_free_chan_resources', which already holds the lock, and from `pl330_del'. Function `pl330_del' is called in an error path of `pl330_probe' and at the end of `pl330_remove', but I assume that there cannot be concurrent accesses to the protected data at those points. Signed-off-by: Iago Abal <mail@iagoabal.eu> Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'fs/xfs/xfs_trans_ail.c')