linux-kernel - [PATCH 4.2.y-ckt 162/273] ALSA: hda - Cancel probe work instead of flush at remove

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Date:	Mon,  7 Mar 2016 14:49:13 -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 4.2.y-ckt 162/273] ALSA: hda - Cancel probe work instead of flush at remove

4.2.8-ckt5 -stable review patch.  If anyone has any objections, please let me know.

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

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

commit 0b8c82190c12e530eb6003720dac103bf63e146e upstream.

The commit [991f86d7ae4e: ALSA: hda - Flush the pending probe work at
remove] introduced the sync of async probe work at remove for fixing
the race.  However, this may lead to another hangup when the module
removal is performed quickly before starting the probe work, because
it issues flush_work() and it's blocked forever.

The workaround is to use cancel_work_sync() instead of flush_work()
there.

Fixes: 991f86d7ae4e ('ALSA: hda - Flush the pending probe work at remove')
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 sound/pci/hda/hda_intel.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index e61fbf4..019390b 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -2104,10 +2104,10 @@ static void azx_remove(struct pci_dev *pci)
 	struct hda_intel *hda;
 
 	if (card) {
-		/* flush the pending probing work */
+		/* cancel the pending probing work */
 		chip = card->private_data;
 		hda = container_of(chip, struct hda_intel, chip);
-		flush_work(&hda->probe_work);
+		cancel_work_sync(&hda->probe_work);
 
 		snd_card_free(card);
 	}
-- 
2.7.0