ALSA: hda - Fix registration race of VGA switcheroo

Delay the registration of VGA switcheroo client to the end of the
probing.  Otherwise a too quick switching may result in Oops during
probing.

Also add the check of the return value from snd_hda_lock_devices().

Reported-and-tested-by: Daniel J Blueman <daniel@quora.org>
Cc: <stable@vger.kernel.org> [v3.5+]
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 20 insertions, 11 deletions

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 69810b21f7f4..ecf277506ad1 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -501,6 +501,7 @@ struct azx {
 
         /* VGA-switcheroo setup */
         unsigned int use_vga_switcheroo:1;
+        unsigned int vga_switcheroo_registered:1;
         unsigned int init_failed:1; /* delayed init failed */
         unsigned int disabled:1; /* disabled by VGA-switcher */
 
@@ -2640,7 +2641,9 @@ static void azx_vs_set_state(struct pci_dev *pci,
                 if (disabled) {
                         azx_suspend(&pci->dev);
                         chip->disabled = true;
-                        snd_hda_lock_devices(chip->bus);
+                        if (snd_hda_lock_devices(chip->bus))
+                                snd_printk(KERN_WARNING SFX
+                                           "Cannot lock devices!\n");
                 } else {
                         snd_hda_unlock_devices(chip->bus);
                         chip->disabled = false;
@@ -2683,14 +2686,20 @@ static const struct vga_switcheroo_client_ops azx_vs_ops = {
 
 static int __devinit register_vga_switcheroo(struct azx *chip)
 {
+        int err;
+
         if (!chip->use_vga_switcheroo)
                 return 0;
         /* FIXME: currently only handling DIS controller
          * is there any machine with two switchable HDMI audio controllers?
          */
-        return vga_switcheroo_register_audio_client(chip->pci, &azx_vs_ops,
+        err = vga_switcheroo_register_audio_client(chip->pci, &azx_vs_ops,
                                                     VGA_SWITCHEROO_DIS,
                                                     chip->bus != NULL);
+        if (err < 0)
+                return err;
+        chip->vga_switcheroo_registered = 1;
+        return 0;
 }
 #else
 #define init_vga_switcheroo(chip)               /* NOP */
@@ -2712,7 +2721,8 @@ static int azx_free(struct azx *chip)
         if (use_vga_switcheroo(chip)) {
                 if (chip->disabled && chip->bus)
                         snd_hda_unlock_devices(chip->bus);
-                vga_switcheroo_unregister_client(chip->pci);
+                if (chip->vga_switcheroo_registered)
+                        vga_switcheroo_unregister_client(chip->pci);
         }
 
         if (chip->initialized) {
@@ -3060,14 +3070,6 @@ static int __devinit azx_create(struct snd_card *card, struct pci_dev *pci,
         }
 
  ok:
-        err = register_vga_switcheroo(chip);
-        if (err < 0) {
-                snd_printk(KERN_ERR SFX
-                           "Error registering VGA-switcheroo client\n");
-                azx_free(chip);
-                return err;
-        }
-
         err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
         if (err < 0) {
                 snd_printk(KERN_ERR SFX "Error creating device [card]!\n");
@@ -3338,6 +3340,13 @@ static int __devinit azx_probe(struct pci_dev *pci,
         if (pci_dev_run_wake(pci))
                 pm_runtime_put_noidle(&pci->dev);
 
+        err = register_vga_switcheroo(chip);
+        if (err < 0) {
+                snd_printk(KERN_ERR SFX
+                           "Error registering VGA-switcheroo client\n");
+                goto out_free;
+        }
+
         dev++;
         return 0;