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47ab154593
After the recent fix of runtime PM for USB-audio driver, we got a
lockdep warning like:
=============================================
[ INFO: possible recursive locking detected ]
4.2.0-rc8+ #61 Not tainted
---------------------------------------------
pulseaudio/980 is trying to acquire lock:
(&chip->shutdown_rwsem){.+.+.+}, at: [<ffffffffa0355dac>] snd_usb_autoresume+0x1d/0x52 [snd_usb_audio]
but task is already holding lock:
(&chip->shutdown_rwsem){.+.+.+}, at: [<ffffffffa0355dac>] snd_usb_autoresume+0x1d/0x52 [snd_usb_audio]
This comes from snd_usb_autoresume() invoking down_read() and it's
used in a nested way. Although it's basically safe, per se (as these
are read locks), it's better to reduce such spurious warnings.
The read lock is needed to guarantee the execution of "shutdown"
(cleanup at disconnection) task after all concurrent tasks are
finished. This can be implemented in another better way.
Also, the current check of chip->in_pm isn't good enough for
protecting the racy execution of multiple auto-resumes.
This patch rewrites the logic of snd_usb_autoresume() & co; namely,
- The recursive call of autopm is avoided by the new refcount,
chip->active. The chip->in_pm flag is removed accordingly.
- Instead of rwsem, another refcount, chip->usage_count, is introduced
for tracking the period to delay the shutdown procedure. At
the last clear of this refcount, wake_up() to the shutdown waiter is
called.
- The shutdown flag is replaced with shutdown atomic count; this is
for reducing the lock.
- Two new helpers are introduced to simplify the management of these
refcounts; snd_usb_lock_shutdown() increases the usage_count, checks
the shutdown state, and does autoresume. snd_usb_unlock_shutdown()
does the opposite. Most of mixer and other codes just need this,
and simply returns an error if it receives an error from lock.
Fixes: 9003ebb13f ('ALSA: usb-audio: Fix runtime PM unbalance')
Reported-and-tested-by: Alexnader Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
123 lines
3.4 KiB
C
123 lines
3.4 KiB
C
#ifndef __USBAUDIO_H
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#define __USBAUDIO_H
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/*
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* (Tentative) USB Audio Driver for ALSA
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*
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* Copyright (c) 2002 by Takashi Iwai <tiwai@suse.de>
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/* handling of USB vendor/product ID pairs as 32-bit numbers */
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#define USB_ID(vendor, product) (((vendor) << 16) | (product))
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#define USB_ID_VENDOR(id) ((id) >> 16)
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#define USB_ID_PRODUCT(id) ((u16)(id))
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/*
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*
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*/
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struct snd_usb_audio {
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int index;
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struct usb_device *dev;
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struct snd_card *card;
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struct usb_interface *pm_intf;
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u32 usb_id;
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struct mutex mutex;
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unsigned int probing:1;
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unsigned int autosuspended:1;
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atomic_t active;
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atomic_t shutdown;
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atomic_t usage_count;
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wait_queue_head_t shutdown_wait;
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unsigned int txfr_quirk:1; /* Subframe boundaries on transfers */
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int num_interfaces;
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int num_suspended_intf;
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struct list_head pcm_list; /* list of pcm streams */
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struct list_head ep_list; /* list of audio-related endpoints */
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int pcm_devs;
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struct list_head midi_list; /* list of midi interfaces */
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struct list_head mixer_list; /* list of mixer interfaces */
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int setup; /* from the 'device_setup' module param */
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bool autoclock; /* from the 'autoclock' module param */
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struct usb_host_interface *ctrl_intf; /* the audio control interface */
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};
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#define usb_audio_err(chip, fmt, args...) \
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dev_err(&(chip)->dev->dev, fmt, ##args)
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#define usb_audio_warn(chip, fmt, args...) \
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dev_warn(&(chip)->dev->dev, fmt, ##args)
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#define usb_audio_info(chip, fmt, args...) \
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dev_info(&(chip)->dev->dev, fmt, ##args)
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#define usb_audio_dbg(chip, fmt, args...) \
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dev_dbg(&(chip)->dev->dev, fmt, ##args)
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/*
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* Information about devices with broken descriptors
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*/
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/* special values for .ifnum */
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#define QUIRK_NO_INTERFACE -2
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#define QUIRK_ANY_INTERFACE -1
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enum quirk_type {
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QUIRK_IGNORE_INTERFACE,
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QUIRK_COMPOSITE,
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QUIRK_AUTODETECT,
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QUIRK_MIDI_STANDARD_INTERFACE,
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QUIRK_MIDI_FIXED_ENDPOINT,
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QUIRK_MIDI_YAMAHA,
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QUIRK_MIDI_ROLAND,
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QUIRK_MIDI_MIDIMAN,
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QUIRK_MIDI_NOVATION,
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QUIRK_MIDI_RAW_BYTES,
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QUIRK_MIDI_EMAGIC,
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QUIRK_MIDI_CME,
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QUIRK_MIDI_AKAI,
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QUIRK_MIDI_US122L,
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QUIRK_MIDI_FTDI,
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QUIRK_AUDIO_STANDARD_INTERFACE,
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QUIRK_AUDIO_FIXED_ENDPOINT,
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QUIRK_AUDIO_EDIROL_UAXX,
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QUIRK_AUDIO_ALIGN_TRANSFER,
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QUIRK_AUDIO_STANDARD_MIXER,
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QUIRK_TYPE_COUNT
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};
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struct snd_usb_audio_quirk {
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const char *vendor_name;
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const char *product_name;
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int16_t ifnum;
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uint16_t type;
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const void *data;
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};
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#define combine_word(s) ((*(s)) | ((unsigned int)(s)[1] << 8))
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#define combine_triple(s) (combine_word(s) | ((unsigned int)(s)[2] << 16))
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#define combine_quad(s) (combine_triple(s) | ((unsigned int)(s)[3] << 24))
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int snd_usb_lock_shutdown(struct snd_usb_audio *chip);
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void snd_usb_unlock_shutdown(struct snd_usb_audio *chip);
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#endif /* __USBAUDIO_H */
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