/* * ALSA sequencer MIDI-through client * Copyright (c) 1999-2000 by Takashi Iwai * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * */ #include #include #include #include #include "seq_clientmgr.h" #include #include /* Sequencer MIDI-through client This gives a simple midi-through client. All the normal input events are redirected to output port immediately. The routing can be done via aconnect program in alsa-utils. Each client has a static client number 62 (= SNDRV_SEQ_CLIENT_DUMMY). If you want to auto-load this module, you may add the following alias in your /etc/conf.modules file. alias snd-seq-client-62 snd-seq-dummy The module is loaded on demand for client 62, or /proc/asound/seq/ is accessed. If you don't need this module to be loaded, alias snd-seq-client-62 as "off". This will help modprobe. The number of ports to be created can be specified via the module parameter "ports". For example, to create four ports, add the following option in a configuration file under /etc/modprobe.d/: option snd-seq-dummy ports=4 The model option "duplex=1" enables duplex operation to the port. In duplex mode, a pair of ports are created instead of single port, and events are tunneled between pair-ports. For example, input to port A is sent to output port of another port B and vice versa. In duplex mode, each port has DUPLEX capability. */ MODULE_AUTHOR("Takashi Iwai "); MODULE_DESCRIPTION("ALSA sequencer MIDI-through client"); MODULE_LICENSE("GPL"); MODULE_ALIAS("snd-seq-client-" __stringify(SNDRV_SEQ_CLIENT_DUMMY)); static int ports = 1; static bool duplex; module_param(ports, int, 0444); MODULE_PARM_DESC(ports, "number of ports to be created"); module_param(duplex, bool, 0444); MODULE_PARM_DESC(duplex, "create DUPLEX ports"); struct snd_seq_dummy_port { int client; int port; int duplex; int connect; }; static int my_client = -1; /* * event input callback - just redirect events to subscribers */ static int dummy_input(struct snd_seq_event *ev, int direct, void *private_data, int atomic, int hop) { struct snd_seq_dummy_port *p; struct snd_seq_event tmpev; p = private_data; if (ev->source.client == SNDRV_SEQ_CLIENT_SYSTEM || ev->type == SNDRV_SEQ_EVENT_KERNEL_ERROR) return 0; /* ignore system messages */ tmpev = *ev; if (p->duplex) tmpev.source.port = p->connect; else tmpev.source.port = p->port; tmpev.dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS; return snd_seq_kernel_client_dispatch(p->client, &tmpev, atomic, hop); } /* * free_private callback */ static void dummy_free(void *private_data) { kfree(private_data); } /* * create a port */ static struct snd_seq_dummy_port __init * create_port(int idx, int type) { struct snd_seq_port_info pinfo; struct snd_seq_port_callback pcb; struct snd_seq_dummy_port *rec; if ((rec = kzalloc(sizeof(*rec), GFP_KERNEL)) == NULL) return NULL; rec->client = my_client; rec->duplex = duplex; rec->connect = 0; memset(&pinfo, 0, sizeof(pinfo)); pinfo.addr.client = my_client; if (duplex) sprintf(pinfo.name, "Midi Through Port-%d:%c", idx, (type ? 'B' : 'A')); else sprintf(pinfo.name, "Midi Through Port-%d", idx); pinfo.capability = SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ; pinfo.capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE; if (duplex) pinfo.capability |= SNDRV_SEQ_PORT_CAP_DUPLEX; pinfo.type = SNDRV_SEQ_PORT_TYPE_MIDI_GENERIC | SNDRV_SEQ_PORT_TYPE_SOFTWARE | SNDRV_SEQ_PORT_TYPE_PORT; memset(&pcb, 0, sizeof(pcb)); pcb.owner = THIS_MODULE; pcb.event_input = dummy_input; pcb.private_free = dummy_free; pcb.private_data = rec; pinfo.kernel = &pcb; if (snd_seq_kernel_client_ctl(my_client, SNDRV_SEQ_IOCTL_CREATE_PORT, &pinfo) < 0) { kfree(rec); return NULL; } rec->port = pinfo.addr.port; return rec; } /* * register client and create ports */ static int __init register_client(void) { struct snd_seq_dummy_port *rec1, *rec2; int i; if (ports < 1) { pr_err("ALSA: seq_dummy: invalid number of ports %d\n", ports); return -EINVAL; } /* create client */ my_client = snd_seq_create_kernel_client(NULL, SNDRV_SEQ_CLIENT_DUMMY, "Midi Through"); if (my_client < 0) return my_client; /* create ports */ for (i = 0; i < ports; i++) { rec1 = create_port(i, 0); if (rec1 == NULL) { snd_seq_delete_kernel_client(my_client); return -ENOMEM; } if (duplex) { rec2 = create_port(i, 1); if (rec2 == NULL) { snd_seq_delete_kernel_client(my_client); return -ENOMEM; } rec1->connect = rec2->port; rec2->connect = rec1->port; } } return 0; } /* * delete client if exists */ static void __exit delete_client(void) { if (my_client >= 0) snd_seq_delete_kernel_client(my_client); } /* * Init part */ static int __init alsa_seq_dummy_init(void) { return register_client(); } static void __exit alsa_seq_dummy_exit(void) { delete_client(); } module_init(alsa_seq_dummy_init) module_exit(alsa_seq_dummy_exit) ='/cgit.cgi/linux/net-next.git/commit/tools/testing/radix-tree/regression.h?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff)
percpu-refcount: fix reference leak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'tools/testing/radix-tree/regression.h')