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    Subject[PATCH 5.16 0826/1017] ALSA: hda: Fix driver index handling at re-binding
    Date
    From: Takashi Iwai <tiwai@suse.de>

    [ Upstream commit 69458e2c27800da7697c87ed908b65323ef3f3bd ]

    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@gmail.com>
    Link: https://lore.kernel.org/r/20220209081912.20687-1-tiwai@suse.de
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 3b6f2aacda45..1ffd96fbf230 100644
    --- a/sound/pci/hda/hda_intel.c
    +++ b/sound/pci/hda/hda_intel.c
    @@ -2061,14 +2061,16 @@ 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)) {
    @@ -2076,10 +2078,11 @@ 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;
    }

    @@ -2146,7 +2149,7 @@ 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;
    @@ -2369,6 +2372,7 @@ 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


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