Re: [RESEND PATCH] staging: bcm2835-audio: Disconnect and free vchi_instance on module_exit()

Dan Carpenter
2018-04-24T11:50:52Z

On Tue, Apr 24, 2018 at 09:44:59AM +0200, Kirill Marinushkin wrote:
> 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: 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
> ---
> .../vc04_services/bcm2835-audio/bcm2835-vchiq.c | 64 +++++++++++++---------
> .../staging/vc04_services/bcm2835-audio/bcm2835.c | 43 ++++++++++++++-
> .../staging/vc04_services/bcm2835-audio/bcm2835.h | 12 ++++
> 3 files changed, 91 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
> index 3c6f1d91d22d..389a18f9350a 100644
> --- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
> +++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
> @@ -33,7 +33,6 @@
>
> /* ---- Include Files -------------------------------------------------------- */
>
> -#include "interface/vchi/vchi.h"
> #include "vc_vchi_audioserv_defs.h"
>
> /* ---- Private Constants and Types ------------------------------------------ */
> @@ -371,14 +370,46 @@ 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);
> @@ -390,28 +421,9 @@ 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__);
> diff --git a/drivers/staging/vc04_services/bcm2835-audio/bcm2835.c b/drivers/staging/vc04_services/bcm2835-audio/bcm2835.c
> index 9030d71a3d0b..009c972d93d6 100644
> --- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835.c
> +++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835.c
> @@ -65,6 +65,36 @@ static int snd_devm_add_child(struct device *dev, struct device *child)
> return 0;
> }
>
> +static void bcm2835_devm_free_vchi_ctx(struct device *dev, void *res)
> +{
> + struct bcm2835_vchi_ctx *vchi_ctx = res;
> +
> + bcm2835_free_vchi_ctx(vchi_ctx);
> +}
> +
> +static int bcm2835_devm_add_vchi_ctx(struct device *dev)
> +{
> + struct bcm2835_vchi_ctx *vchi_ctx;
> + int ret;
> +
> + vchi_ctx = devres_alloc(bcm2835_devm_free_vchi_ctx, sizeof(*vchi_ctx),
> + GFP_KERNEL);
> + if (!vchi_ctx)
> + return -ENOMEM;
> +
> + memset(vchi_ctx, 0, sizeof(*vchi_ctx));
> +
> + ret = bcm2835_new_vchi_ctx(vchi_ctx);
> + if (ret) {
> + devres_free(vchi_ctx);
> + return ret;
> + }
> +
> + devres_add(dev, vchi_ctx);
> +
> + return 0;
> +}
> +
> static void snd_bcm2835_release(struct device *dev)
> {
> struct bcm2835_chip *chip = dev_get_drvdata(dev);
> @@ -106,8 +136,6 @@ static int snd_bcm2835_dev_free(struct snd_device *device)
> struct bcm2835_chip *chip = device->device_data;
> struct snd_card *card = chip->card;
>
> - /* TODO: free pcm, ctl */
> -
> snd_device_free(card, chip);
>
> return 0;
> @@ -133,6 +161,13 @@ static int snd_bcm2835_create(struct snd_card *card,
>
> chip->card = card;
>
> + chip->vchi_ctx = devres_find(card->dev->parent,
> + bcm2835_devm_free_vchi_ctx, NULL, NULL);
> + if (!chip->vchi_ctx) {
> + kfree(chip);
> + return err;

kbuild is complaining that "err" is uninitialized here but for some
reason the line numbers are off. It's a real bug.

regards,
dan carpenter