On 5/30/19 3:18 PM, Ranjani Sridharan wrote:
Calling snd_device_new() makes the codec devices managed by the card. So, when the card is removed, the refcount for the codec device is decremented and results in the codec device's kobject being cleaned up if the refcount is 0. But, this leads to a NULL pointer exception while attempting to remove the symlinks when the codec driver is released later on. Therefore, increment the codec device's refcount before adding it to the card to prevent this.
Ranjani, you should add a bit of context for the rest of the list...
This patch suggest a solution to a set of sightings occurring when removing/adding modules in a loop, and the current analysis points to a difference between the way the HDMI and HDaudio codecs are handled.
https://github.com/thesofproject/linux/issues/981 https://github.com/thesofproject/linux/issues/966 https://github.com/thesofproject/linux/pull/988
Since it's not SOF specific it's better to get feedback directly from the large ALSA community/maintainers. We probably want to focus on the platform-specific/vendor-specific stuff on GitHub and use the mailing list for such framework-level changes.
Signed-off-by: Ranjani Sridharan ranjani.sridharan@linux.intel.com
sound/pci/hda/hda_codec.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c index b20eb7fc83eb..0d5d95b07e19 100644 --- a/sound/pci/hda/hda_codec.c +++ b/sound/pci/hda/hda_codec.c @@ -985,6 +985,14 @@ int snd_hda_codec_device_new(struct hda_bus *bus, struct snd_card *card, codec->core.subsystem_id, codec->core.revision_id); snd_component_add(card, component);
- /*
* snd_device_new() makes the codec device managed by the card.* When the card is removed, the device reference count is* decremented. Therefore, increment it here to prevent removing* the codec device's kobject when the card is removed.*/- get_device(hda_codec_dev(codec));
- err = snd_device_new(card, SNDRV_DEV_CODEC, codec, &dev_ops); if (err < 0) goto error;