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40cab6e88c
OSS PCM stream management isn't modal but it allows ioctls issued at
any time for changing the parameters. In the previous hardening
patch ("ALSA: pcm: Avoid potential races between OSS ioctls and
read/write"), we covered these races and prevent the corruption by
protecting the concurrent accesses via params_lock mutex. However,
this means that some ioctls that try to change the stream parameter
(e.g. channels or format) would be blocked until the read/write
finishes, and it may take really long.
Basically changing the parameter while reading/writing is an invalid
operation, hence it's even more user-friendly from the API POV if it
returns -EBUSY in such a situation.
This patch adds such checks in the relevant ioctls with the addition
of read/write access refcount.
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
91 lines
2.7 KiB
C
91 lines
2.7 KiB
C
#ifndef __SOUND_PCM_OSS_H
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#define __SOUND_PCM_OSS_H
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/*
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* Digital Audio (PCM) - OSS compatibility abstract layer
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* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
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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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*/
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struct snd_pcm_oss_setup {
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char *task_name;
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unsigned int disable:1,
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direct:1,
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block:1,
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nonblock:1,
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partialfrag:1,
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nosilence:1,
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buggyptr:1;
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unsigned int periods;
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unsigned int period_size;
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struct snd_pcm_oss_setup *next;
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};
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struct snd_pcm_oss_runtime {
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unsigned params: 1, /* format/parameter change */
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prepare: 1, /* need to prepare the operation */
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trigger: 1, /* trigger flag */
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sync_trigger: 1; /* sync trigger flag */
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int rate; /* requested rate */
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int format; /* requested OSS format */
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unsigned int channels; /* requested channels */
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unsigned int fragshift;
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unsigned int maxfrags;
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unsigned int subdivision; /* requested subdivision */
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size_t period_bytes; /* requested period size */
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size_t period_frames; /* period frames for poll */
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size_t period_ptr; /* actual write pointer to period */
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unsigned int periods;
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size_t buffer_bytes; /* requested buffer size */
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size_t bytes; /* total # bytes processed */
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size_t mmap_bytes;
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char *buffer; /* vmallocated period */
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size_t buffer_used; /* used length from period buffer */
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struct mutex params_lock;
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atomic_t rw_ref; /* concurrent read/write accesses */
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#ifdef CONFIG_SND_PCM_OSS_PLUGINS
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struct snd_pcm_plugin *plugin_first;
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struct snd_pcm_plugin *plugin_last;
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#endif
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unsigned int prev_hw_ptr_period;
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};
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struct snd_pcm_oss_file {
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struct snd_pcm_substream *streams[2];
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};
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struct snd_pcm_oss_substream {
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unsigned oss: 1; /* oss mode */
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struct snd_pcm_oss_setup setup; /* active setup */
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};
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struct snd_pcm_oss_stream {
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struct snd_pcm_oss_setup *setup_list; /* setup list */
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struct mutex setup_mutex;
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#ifdef CONFIG_SND_VERBOSE_PROCFS
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struct snd_info_entry *proc_entry;
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#endif
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};
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struct snd_pcm_oss {
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int reg;
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unsigned int reg_mask;
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};
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#endif /* __SOUND_PCM_OSS_H */
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