/* * digi00x-hwdep.c - a part of driver for Digidesign Digi 002/003 family * * Copyright (c) 2014-2015 Takashi Sakamoto * * Licensed under the terms of the GNU General Public License, version 2. */ /* * This codes give three functionality. * * 1.get firewire node information * 2.get notification about starting/stopping stream * 3.lock/unlock stream * 4.get asynchronous messaging */ #include "digi00x.h" static long hwdep_read(struct snd_hwdep *hwdep, char __user *buf, long count, loff_t *offset) { struct snd_dg00x *dg00x = hwdep->private_data; DEFINE_WAIT(wait); union snd_firewire_event event; spin_lock_irq(&dg00x->lock); while (!dg00x->dev_lock_changed && dg00x->msg == 0) { prepare_to_wait(&dg00x->hwdep_wait, &wait, TASK_INTERRUPTIBLE); spin_unlock_irq(&dg00x->lock); schedule(); finish_wait(&dg00x->hwdep_wait, &wait); if (signal_pending(current)) return -ERESTARTSYS; spin_lock_irq(&dg00x->lock); } memset(&event, 0, sizeof(event)); if (dg00x->dev_lock_changed) { event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS; event.lock_status.status = (dg00x->dev_lock_count > 0); dg00x->dev_lock_changed = false; count = min_t(long, count, sizeof(event.lock_status)); } else { event.digi00x_message.type = SNDRV_FIREWIRE_EVENT_DIGI00X_MESSAGE; event.digi00x_message.message = dg00x->msg; dg00x->msg = 0; count = min_t(long, count, sizeof(event.digi00x_message)); } spin_unlock_irq(&dg00x->lock); if (copy_to_user(buf, &event, count)) return -EFAULT; return count; } static unsigned int hwdep_poll(struct snd_hwdep *hwdep, struct file *file, poll_table *wait) { struct snd_dg00x *dg00x = hwdep->private_data; unsigned int events; poll_wait(file, &dg00x->hwdep_wait, wait); spin_lock_irq(&dg00x->lock); if (dg00x->dev_lock_changed || dg00x->msg) events = POLLIN | POLLRDNORM; else events = 0; spin_unlock_irq(&dg00x->lock); return events; } static int hwdep_get_info(struct snd_dg00x *dg00x, void __user *arg) { struct fw_device *dev = fw_parent_device(dg00x->unit); struct snd_firewire_get_info info; memset(&info, 0, sizeof(info)); info.type = SNDRV_FIREWIRE_TYPE_DIGI00X; info.card = dev->card->index; *(__be32 *)&info.guid[0] = cpu_to_be32(dev->config_rom[3]); *(__be32 *)&info.guid[4] = cpu_to_be32(dev->config_rom[4]); strlcpy(info.device_name, dev_name(&dev->device), sizeof(info.device_name)); if (copy_to_user(arg, &info, sizeof(info))) return -EFAULT; return 0; } static int hwdep_lock(struct snd_dg00x *dg00x) { int err; spin_lock_irq(&dg00x->lock); if (dg00x->dev_lock_count == 0) { dg00x->dev_lock_count = -1; err = 0; } else { err = -EBUSY; } spin_unlock_irq(&dg00x->lock); return err; } static int hwdep_unlock(struct snd_dg00x *dg00x) { int err; spin_lock_irq(&dg00x->lock); if (dg00x->dev_lock_count == -1) { dg00x->dev_lock_count = 0; err = 0; } else { err = -EBADFD; } spin_unlock_irq(&dg00x->lock); return err; } static int hwdep_release(struct snd_hwdep *hwdep, struct file *file) { struct snd_dg00x *dg00x = hwdep->private_data; spin_lock_irq(&dg00x->lock); if (dg00x->dev_lock_count == -1) dg00x->dev_lock_count = 0; spin_unlock_irq(&dg00x->lock); return 0; } static int hwdep_ioctl(struct snd_hwdep *hwdep, struct file *file, unsigned int cmd, unsigned long arg) { struct snd_dg00x *dg00x = hwdep->private_data; switch (cmd) { case SNDRV_FIREWIRE_IOCTL_GET_INFO: return hwdep_get_info(dg00x, (void __user *)arg); case SNDRV_FIREWIRE_IOCTL_LOCK: return hwdep_lock(dg00x); case SNDRV_FIREWIRE_IOCTL_UNLOCK: return hwdep_unlock(dg00x); default: return -ENOIOCTLCMD; } } #ifdef CONFIG_COMPAT static int hwdep_compat_ioctl(struct snd_hwdep *hwdep, struct file *file, unsigned int cmd, unsigned long arg) { return hwdep_ioctl(hwdep, file, cmd, (unsigned long)compat_ptr(arg)); } #else #define hwdep_compat_ioctl NULL #endif static const struct snd_hwdep_ops hwdep_ops = { .read = hwdep_read, .release = hwdep_release, .poll = hwdep_poll, .ioctl = hwdep_ioctl, .ioctl_compat = hwdep_compat_ioctl, }; int snd_dg00x_create_hwdep_device(struct snd_dg00x *dg00x) { struct snd_hwdep *hwdep; int err; err = snd_hwdep_new(dg00x->card, "Digi00x", 0, &hwdep); if (err < 0) return err; strcpy(hwdep->name, "Digi00x"); hwdep->iface = SNDRV_HWDEP_IFACE_FW_DIGI00X; hwdep->ops = hwdep_ops; hwdep->private_data = dg00x; hwdep->exclusive = true; return err; } ignoremode:
authorDouglas Miller <dougmill@linux.vnet.ibm.com>2017-01-28 06:42:20 -0600
committerTejun Heo <tj@kernel.org>2017-01-28 07:49:42 -0500
commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch)
tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /sound/arm/pxa2xx-ac97.c
parent1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (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 'sound/arm/pxa2xx-ac97.c')