From c3aeda62878f09da91329693a60a1f08ec97e0b8 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 13 Apr 2015 11:01:14 +0200 Subject: 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 --- sound/hda/hdac_device.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'sound') diff --git a/sound/hda/hdac_device.c b/sound/hda/hdac_device.c index 92604bbcee5f..f75bf5622687 100644 --- a/sound/hda/hdac_device.c +++ b/sound/hda/hdac_device.c @@ -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 */ -- cgit v1.2.3-59-g8ed1b