/* * Created by: Jason Wessel * * Copyright (c) 2010 Wind River Systems, Inc. All Rights Reserved. * * This file is licensed under the terms of the GNU General Public * License version 2. This program is licensed "as is" without any * warranty of any kind, whether express or implied. */ #include #include /* * All kdb shell command call backs receive argc and argv, where * argv[0] is the command the end user typed */ static int kdb_hello_cmd(int argc, const char **argv) { if (argc > 1) return KDB_ARGCOUNT; if (argc) kdb_printf("Hello %s.\n", argv[1]); else kdb_printf("Hello world!\n"); return 0; } static int __init kdb_hello_cmd_init(void) { /* * Registration of a dynamically added kdb command is done with * kdb_register() with the arguments being: * 1: The name of the shell command * 2: The function that processes the command * 3: Description of the usage of any arguments * 4: Descriptive text when you run help * 5: Number of characters to complete the command * 0 == type the whole command * 1 == match both "g" and "go" for example */ kdb_register("hello", kdb_hello_cmd, "[string]", "Say Hello World or Hello [string]", 0); return 0; } static void __exit kdb_hello_cmd_exit(void) { kdb_unregister("hello"); } module_init(kdb_hello_cmd_init); module_exit(kdb_hello_cmd_exit); MODULE_AUTHOR("WindRiver"); MODULE_DESCRIPTION("KDB example to add a hello command"); MODULE_LICENSE("GPL"); > summaryrefslogtreecommitdiff
path: root/net/dccp/ackvec.c
diff options
context:
space:
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 /net/dccp/ackvec.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 'net/dccp/ackvec.c')