Patchwork [3.5.y.z,extended,stable] Patch "ALSA: usb-audio: Avoid autopm calls after disconnection" has been added to staging queue

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Submitter Herton Ronaldo Krzesinski
Date Jan. 7, 2013, 8:36 p.m.
Message ID <1357591001-20625-1-git-send-email-herton.krzesinski@canonical.com>
Download mbox | patch
Permalink /patch/210189/
State New
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Herton Ronaldo Krzesinski - Jan. 7, 2013, 8:36 p.m.
This is a note to let you know that I have just added a patch titled

    ALSA: usb-audio: Avoid autopm calls after disconnection

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

From ca1ff9bc982d25d413f9613837184d49397e228d Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 3 Dec 2012 11:12:46 +0100
Subject: [PATCH] ALSA: usb-audio: Avoid autopm calls after disconnection

commit 59866da9e4ae54819e3c4e0a8f426bdb0c2ef993 upstream.

Add a similar protection against the disconnection race and the
invalid use of usb instance after disconnection, as well as we've done
for the USB audio PCM.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=51201

Reviewd-by: Clemens Ladisch <clemens@ladisch.de>
Tested-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
 sound/usb/midi.c |   23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

--
1.7.9.5

Patch

diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index eeefbce..c0054ee 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -116,6 +116,7 @@  struct snd_usb_midi {
 	struct list_head list;
 	struct timer_list error_timer;
 	spinlock_t disc_lock;
+	struct rw_semaphore disc_rwsem;
 	struct mutex mutex;
 	u32 usb_id;
 	int next_midi_device;
@@ -1038,6 +1039,12 @@  static void substream_open(struct snd_rawmidi_substream *substream, int open)
 	struct snd_usb_midi* umidi = substream->rmidi->private_data;
 	struct snd_kcontrol *ctl;

+	down_read(&umidi->disc_rwsem);
+	if (umidi->disconnected) {
+		up_read(&umidi->disc_rwsem);
+		return;
+	}
+
 	mutex_lock(&umidi->mutex);
 	if (open) {
 		if (umidi->opened++ == 0 && umidi->roland_load_ctl) {
@@ -1056,6 +1063,7 @@  static void substream_open(struct snd_rawmidi_substream *substream, int open)
 		}
 	}
 	mutex_unlock(&umidi->mutex);
+	up_read(&umidi->disc_rwsem);
 }

 static int snd_usbmidi_output_open(struct snd_rawmidi_substream *substream)
@@ -1076,8 +1084,15 @@  static int snd_usbmidi_output_open(struct snd_rawmidi_substream *substream)
 		snd_BUG();
 		return -ENXIO;
 	}
+
+	down_read(&umidi->disc_rwsem);
+	if (umidi->disconnected) {
+		up_read(&umidi->disc_rwsem);
+		return -ENODEV;
+	}
 	err = usb_autopm_get_interface(umidi->iface);
 	port->autopm_reference = err >= 0;
+	up_read(&umidi->disc_rwsem);
 	if (err < 0 && err != -EACCES)
 		return -EIO;
 	substream->runtime->private_data = port;
@@ -1092,8 +1107,10 @@  static int snd_usbmidi_output_close(struct snd_rawmidi_substream *substream)
 	struct usbmidi_out_port *port = substream->runtime->private_data;

 	substream_open(substream, 0);
-	if (port->autopm_reference)
+	down_read(&umidi->disc_rwsem);
+	if (!umidi->disconnected && port->autopm_reference)
 		usb_autopm_put_interface(umidi->iface);
+	up_read(&umidi->disc_rwsem);
 	return 0;
 }

@@ -1403,9 +1420,12 @@  void snd_usbmidi_disconnect(struct list_head* p)
 	 * a timer may submit an URB. To reliably break the cycle
 	 * a flag under lock must be used
 	 */
+	down_write(&umidi->disc_rwsem);
 	spin_lock_irq(&umidi->disc_lock);
 	umidi->disconnected = 1;
 	spin_unlock_irq(&umidi->disc_lock);
+	up_write(&umidi->disc_rwsem);
+
 	for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i) {
 		struct snd_usb_midi_endpoint* ep = &umidi->endpoints[i];
 		if (ep->out)
@@ -2117,6 +2137,7 @@  int snd_usbmidi_create(struct snd_card *card,
 	umidi->usb_protocol_ops = &snd_usbmidi_standard_ops;
 	init_timer(&umidi->error_timer);
 	spin_lock_init(&umidi->disc_lock);
+	init_rwsem(&umidi->disc_rwsem);
 	mutex_init(&umidi->mutex);
 	umidi->usb_id = USB_ID(le16_to_cpu(umidi->dev->descriptor.idVendor),
 			       le16_to_cpu(umidi->dev->descriptor.idProduct));