On Tue, Feb 08, 2022 at 03:36:08PM +0100, Takashi Iwai wrote:
> ... and here is a fix patch for allowing more rebinds.
> Give it a try.
It works, no problems with large numbers of rebinds.
> -- 8< --
> From: Takashi Iwai <tiwai@xxxxxxx>
> Subject: [PATCH] ALSA: hda: Fix driver index handling at re-binding
>
> HD-audio driver handles the multiple instances and keeps the static
> index that is incremented at each probe. This becomes a problem when
> user tries to re-bind the device via sysfs multiple times; as the
> device index isn't cleared unlike rmmod case, it points to the next
> element at re-binding, and eventually later you can't probe any more
> when it reaches to SNDRV_CARDS_MAX (usually 32).
>
> This patch is an attempt to improve the handling at rebinding.
> Instead of a static device index, now we keep a bitmap and assigns to
> the first zero bit position. At the driver remove, in return, the
> bitmap slot is cleared again, so that it'll be available for the next
> probe.
>
> Reported-by: Alexander Sergeyev <sergeev917@xxxxxxxxx>
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
> ---
> sound/pci/hda/hda_intel.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 4b0338c4c543..a2922233e85f 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -2064,14 +2064,16 @@ static const struct hda_controller_ops pci_hda_ops = {
> .position_check = azx_position_check,
> };
>
> +static DECLARE_BITMAP(probed_devs, SNDRV_CARDS);
> +
> static int azx_probe(struct pci_dev *pci,
> const struct pci_device_id *pci_id)
> {
> - static int dev;
> struct snd_card *card;
> struct hda_intel *hda;
> struct azx *chip;
> bool schedule_probe;
> + int dev;
> int err;
>
> if (pci_match_id(driver_denylist, pci)) {
> @@ -2079,10 +2081,11 @@ static int azx_probe(struct pci_dev *pci,
> return -ENODEV;
> }
>
> + dev = find_first_zero_bit(probed_devs, SNDRV_CARDS);
> if (dev >= SNDRV_CARDS)
> return -ENODEV;
> if (!enable[dev]) {
> - dev++;
> + set_bit(dev, probed_devs);
> return -ENOENT;
> }
>
> @@ -2149,7 +2152,7 @@ static int azx_probe(struct pci_dev *pci,
> if (schedule_probe)
> schedule_delayed_work(&hda->probe_work, 0);
>
> - dev++;
> + set_bit(dev, probed_devs);
> if (chip->disabled)
> complete_all(&hda->probe_wait);
> return 0;
> @@ -2372,6 +2375,7 @@ static void azx_remove(struct pci_dev *pci)
> cancel_delayed_work_sync(&hda->probe_work);
> device_lock(&pci->dev);
>
> + clear_bit(chip->dev_index, probed_devs);
> pci_set_drvdata(pci, NULL);
> snd_card_free(card);
> }
> --
> 2.34.1
>
