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ALSA: hda - Fix another race in runtime PM refcounting 

Although some races in runtime PM refcount was fixed by the commit
[664c715573c2: ALSA: hda - Work around races of power up/down with
runtime PM], there is still a race in the following case:

CPU0:                   CPU1 :
runtime suspend:
  codec->in_pm = 1
                        snd_hdac_power_up_pm():
                          pm_runtime_get_sync() skipped
suspend finished:
  codec->in_pm = 0
                        snd_hdac_power_down_pm():
                          pm_runtime_put_*() is called!

For avoiding this situation, increment in_pm flag atomically when it's
non-zero, and decrement accordingly, to ensure that in_pm is set
consistently for the whole concurrent operations.

Also, since atomic_inc_not_zero() and atomic_dec_if_positive() are
lengthy inline functions, move snd_hdac_power_up_pm() and _down_pm()
to sound/hda/hdac_device.c as no inline functions.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2015-04-13 11:01:14 +02:00
parent eacf6e0a23
commit c3aeda6287
2 changed files with 34 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
include/sound/hdaudio.h
View File

@ -139,39 +139,15 @@ static inline int snd_hdac_read_parm(struct hdac_device *codec, hda_nid_t nid,
#ifdef CONFIG_PM
void snd_hdac_power_up(struct hdac_device *codec);
void snd_hdac_power_down(struct hdac_device *codec);
void snd_hdac_power_up_pm(struct hdac_device *codec);
void snd_hdac_power_down_pm(struct hdac_device *codec);
#else
static inline void snd_hdac_power_up(struct hdac_device *codec) {}
static inline void snd_hdac_power_down(struct hdac_device *codec) {}
static inline void snd_hdac_power_up_pm(struct hdac_device *codec) {}
static inline void snd_hdac_power_down_pm(struct hdac_device *codec) {}
#endif
/**
* snd_hdac_power_up_pm - power up the codec
* @codec: the codec object
*
* This function can be called in a recursive code path like init code
* which may be called by PM suspend/resume again. OTOH, if a power-up
* call must wake up the sleeper (e.g. in a kctl callback), use
* snd_hdac_power_up() instead.
*/
static inline void snd_hdac_power_up_pm(struct hdac_device *codec)
{
if (!atomic_read(&codec->in_pm))
snd_hdac_power_up(codec);
}
/**
* snd_hdac_power_down_pm - power down the codec
* @codec: the codec object
*
* Like snd_hdac_power_up_pm(), this function is used in a recursive
* code path like init code which may be called by PM suspend/resume again.
*/
static inline void snd_hdac_power_down_pm(struct hdac_device *codec)
{
if (!atomic_read(&codec->in_pm))
snd_hdac_power_down(codec);
}
/*
* HD-audio codec base driver
*/

30
sound/hda/hdac_device.c
View File

@ -519,6 +519,36 @@ void snd_hdac_power_down(struct hdac_device *codec)
pm_runtime_put_autosuspend(dev);
}
EXPORT_SYMBOL_GPL(snd_hdac_power_down);
/**
* snd_hdac_power_up_pm - power up the codec
* @codec: the codec object
*
* This function can be called in a recursive code path like init code
* which may be called by PM suspend/resume again. OTOH, if a power-up
* call must wake up the sleeper (e.g. in a kctl callback), use
* snd_hdac_power_up() instead.
*/
void snd_hdac_power_up_pm(struct hdac_device *codec)
{
if (!atomic_inc_not_zero(&codec->in_pm))
snd_hdac_power_up(codec);
}
EXPORT_SYMBOL_GPL(snd_hdac_power_up_pm);
/**
* snd_hdac_power_down_pm - power down the codec
* @codec: the codec object
*
* Like snd_hdac_power_up_pm(), this function is used in a recursive
* code path like init code which may be called by PM suspend/resume again.
*/
void snd_hdac_power_down_pm(struct hdac_device *codec)
{
if (atomic_dec_if_positive(&codec->in_pm) < 0)
snd_hdac_power_down(codec);
}
EXPORT_SYMBOL_GPL(snd_hdac_power_down_pm);
#endif
/* codec vendor labels */