staging: bcm2835-audio: Disconnect and free vchi_instance on module_exit()

In the current implementation, vchi_instance is inited during the first
call of bcm2835_audio_open_connection(), and is never freed. It causes a
memory leak when the module `snd_bcm2835` is removed.

Here is how this commit fixes it:

* the VCHI context (including vchi_instance) is created once in the
  platform's devres
* the VCHI context is allocated and connected once during module_init()
* all created bcm2835_chips have a pointer to this VCHI context
* bcm2835_audio_open_connection() can access the VCHI context through the
  associated bcm2835_chip
* the VCHI context is disconnected and freed once during module_exit()

After this commit is applied, I don't see other issues with the module's
init/exit, so I also remove the associated TODO task.

Steps to reproduce the memory leak before this commit:

~~~~
root@raspberrypi:/home/pi# aplay test0.wav
Playing WAVE 'test0.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Ster
^CAborted by signal Interrupt...
root@raspberrypi:/home/pi# rmmod snd_bcm2835
root@raspberrypi:/home/pi# modprobe snd_bcm2835
root@raspberrypi:/home/pi# aplay test0.wav
Playing WAVE 'test0.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Ster
^CAborted by signal Interrupt...
root@raspberrypi:/home/pi# echo scan > /sys/kernel/debug/kmemleak
root@raspberrypi:/home/pi# cat /sys/kernel/debug/kmemleak
unreferenced object 0xb6794c00 (size 128):
  comm "aplay", pid 406, jiffies 36870 (age 116.650s)
  hex dump (first 32 bytes):
    08 a5 82 81 01 00 00 00 08 4c 79 b6 08 4c 79 b6  .........Ly..Ly.
    00 00 00 00 00 00 00 00 ad 4e ad de ff ff ff ff  .........N......
  backtrace:
    [<802af5e0>] kmem_cache_alloc_trace+0x294/0x3d0
    [<806ce620>] vchiq_initialise+0x98/0x1b0
    [<806d0b34>] vchi_initialise+0x24/0x34
    [<7f1311ec>] 0x7f1311ec
    [<7f1303bc>] 0x7f1303bc
    [<7f130590>] 0x7f130590
    [<7f111fd8>] snd_pcm_open_substream+0x68/0xc4 [snd_pcm]
    [<7f112108>] snd_pcm_open+0xd4/0x248 [snd_pcm]
    [<7f112334>] snd_pcm_playback_open+0x4c/0x6c [snd_pcm]
    [<7f0e250c>] snd_open+0xa8/0x14c [snd]
    [<802ce590>] chrdev_open+0xac/0x188
    [<802c57b4>] do_dentry_open+0x10c/0x314
    [<802c6ba8>] vfs_open+0x5c/0x88
    [<802d9a68>] path_openat+0x368/0x944
    [<802dacd4>] do_filp_open+0x70/0xc4
    [<802c6f70>] do_sys_open+0x110/0x1d4
~~~~

Signed-off-by: Kirill Marinushkin <k.marinushkin@gmail.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: linux-rpi-kernel@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: devel@driverdev.osuosl.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 38 insertions, 26 deletions

diff --git a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
index a4a48f31f1a3..f0cefa1b7b0f 100644
--- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
@@ -22,7 +22,6 @@
 
 /* ---- Include Files -------------------------------------------------------- */
 
-#include "interface/vchi/vchi.h"
 #include "vc_vchi_audioserv_defs.h"
 
 /* ---- Private Constants and Types ------------------------------------------ */
@@ -360,14 +359,46 @@ static int vc_vchi_audio_deinit(struct bcm2835_audio_instance *instance)
 	return 0;
 }
 
+int bcm2835_new_vchi_ctx(struct bcm2835_vchi_ctx *vchi_ctx)
+{
+	int ret;
+
+	/* Initialize and create a VCHI connection */
+	ret = vchi_initialise(&vchi_ctx->vchi_instance);
+	if (ret) {
+		LOG_ERR("%s: failed to initialise VCHI instance (ret=%d)\n",
+			__func__, ret);
+
+		return -EIO;
+	}
+
+	ret = vchi_connect(NULL, 0, vchi_ctx->vchi_instance);
+	if (ret) {
+		LOG_ERR("%s: failed to connect VCHI instance (ret=%d)\n",
+			__func__, ret);
+
+		kfree(vchi_ctx->vchi_instance);
+		vchi_ctx->vchi_instance = NULL;
+
+		return -EIO;
+	}
+
+	return 0;
+}
+
+void bcm2835_free_vchi_ctx(struct bcm2835_vchi_ctx *vchi_ctx)
+{
+	/* Close the VCHI connection - it will also free vchi_instance */
+	WARN_ON(vchi_disconnect(vchi_ctx->vchi_instance));
+
+	vchi_ctx->vchi_instance = NULL;
+}
+
 static int bcm2835_audio_open_connection(struct bcm2835_alsa_stream *alsa_stream)
 {
-	static VCHI_INSTANCE_T vchi_instance;
-	static VCHI_CONNECTION_T *vchi_connection;
-	static int initted;
 	struct bcm2835_audio_instance *instance =
 		(struct bcm2835_audio_instance *)alsa_stream->instance;
-	int ret;
+	struct bcm2835_vchi_ctx *vhci_ctx = alsa_stream->chip->vchi_ctx;
 
 	LOG_INFO("%s: start\n", __func__);
 	BUG_ON(instance);
@@ -379,28 +410,9 @@ static int bcm2835_audio_open_connection(struct bcm2835_alsa_stream *alsa_stream
 		return 0;
 	}
 
-	/* Initialize and create a VCHI connection */
-	if (!initted) {
-		ret = vchi_initialise(&vchi_instance);
-		if (ret) {
-			LOG_ERR("%s: failed to initialise VCHI instance (ret=%d)\n",
-				__func__, ret);
-
-			return -EIO;
-		}
-		ret = vchi_connect(NULL, 0, vchi_instance);
-		if (ret) {
-			LOG_ERR("%s: failed to connect VCHI instance (ret=%d)\n",
-				__func__, ret);
-
-			kfree(vchi_instance);
-			return -EIO;
-		}
-		initted = 1;
-	}
-
 	/* Initialize an instance of the audio service */
-	instance = vc_vchi_audio_init(vchi_instance, &vchi_connection, 1);
+	instance = vc_vchi_audio_init(vhci_ctx->vchi_instance,
+				      &vhci_ctx->vchi_connection, 1);
 
 	if (IS_ERR(instance)) {
 		LOG_ERR("%s: failed to initialize audio service\n", __func__);