linux-kernel - [PATCH 3.19.y-ckt 144/210] ALSA: hda - Flush the pending probe work at remove

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Date:	Thu, 28 Jan 2016 17:18:02 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Takashi Iwai <tiwai@...e.de>, Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 144/210] ALSA: hda - Flush the pending probe work at remove

3.19.8-ckt14 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Takashi Iwai <tiwai@...e.de>

commit 991f86d7ae4e1f8c15806e62f97af519e3cdd860 upstream.

As HD-audio driver does deferred probe internally via workqueue, the
driver might go into the mixed state doing both probe and remove when
the module gets unloaded during the probe work.  This eventually
triggers an Oops, unsurprisingly.

For avoiding this race, we just need to flush the pending probe work
explicitly before actually starting the resource release.

Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=960710
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 sound/pci/hda/hda_intel.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 1b6b75f..8751192 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -2024,9 +2024,17 @@ out_free:
 static void azx_remove(struct pci_dev *pci)
 {
 	struct snd_card *card = pci_get_drvdata(pci);
+	struct azx *chip;
+	struct hda_intel *hda;
+
+	if (card) {
+		/* flush the pending probing work */
+		chip = card->private_data;
+		hda = container_of(chip, struct hda_intel, chip);
+		flush_work(&hda->probe_work);
 
-	if (card)
 		snd_card_free(card);
+	}
 }
 
 /* PCI IDs */
-- 
1.9.1