[PATCH 4.14 176/205] ALSA: hda - Serialize codec registrations

Greg Kroah-Hartman
2019-02-11T15:02:46Z

From: Takashi Iwai <tiwai@suse.de>

commit 305a0ade180981686eec1f92aa6252a7c6ebb1cf upstream.

In the current code, the codec registration may happen both at the
codec bind time and the end of the controller probe time. In a rare
occasion, they race with each other, leading to Oops due to the still
uninitialized card device.

This patch introduces a simple flag to prevent the codec registration
at the codec bind time as long as the controller probe is going on.
The controller probe invokes snd_card_register() that does the whole
registration task, and we don't need to register each piece
beforehand.

Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/pci/hda/hda_bind.c | 3 ++-
sound/pci/hda/hda_codec.h | 1 +
sound/pci/hda/hda_intel.c | 2 ++
3 files changed, 5 insertions(+), 1 deletion(-)

--- a/sound/pci/hda/hda_bind.c
+++ b/sound/pci/hda/hda_bind.c
@@ -109,7 +109,8 @@ static int hda_codec_driver_probe(struct
err = snd_hda_codec_build_controls(codec);
if (err < 0)
goto error_module;
- if (codec->card->registered) {
+ /* only register after the bus probe finished; otherwise it's racy */
+ if (!codec->bus->bus_probing && codec->card->registered) {
err = snd_card_register(codec->card);
if (err < 0)
goto error_module;
--- a/sound/pci/hda/hda_codec.h
+++ b/sound/pci/hda/hda_codec.h
@@ -68,6 +68,7 @@ struct hda_bus {
unsigned int response_reset:1; /* controller was reset */
unsigned int in_reset:1; /* during reset operation */
unsigned int no_response_fallback:1; /* don't fallback at RIRB error */
+ unsigned int bus_probing :1; /* during probing process */

int primary_dig_out_type; /* primary digital out PCM type */
unsigned int mixer_assigned; /* codec addr for mixer name */
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -2236,6 +2236,7 @@ static int azx_probe_continue(struct azx
int val;
int err;

+ to_hda_bus(bus)->bus_probing = 1;
hda->probe_continued = 1;

/* bind with i915 if needed */
@@ -2341,6 +2342,7 @@ i915_power_fail:
if (err < 0)
hda->init_failed = 1;
complete_all(&hda->probe_wait);
+ to_hda_bus(bus)->bus_probing = 0;
return err;
}