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Subject: Re: [PATCH v4 2/5] media: vimc: Fix gpf in rmmod path when stream is
 active
To:     Shuah Khan <skhan@linuxfoundation.org>, mchehab@kernel.org,
        andrealmeid@collabora.com, dafna.hirschfeld@collabora.com,
        hverkuil-cisco@xs4all.nl
Cc:     linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
References: <cover.1567822792.git.skhan@linuxfoundation.org>
 <2421a0ea4bec8c5084121ecdbc9213c331239f3d.1567822793.git.skhan@linuxfoundation.org>
From:   Helen Koike <helen.koike@collabora.com>
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Message-ID: <05f955ad-525a-cabf-637f-d68a1ac43e33@collabora.com>
Date:   Sun, 15 Sep 2019 16:25:36 -0300
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On 9/6/19 11:42 PM, Shuah Khan wrote:
> If vimc module is removed while streaming is in progress, sensor subdev
> unregister runs into general protection fault when it tries to unregister
> media entities. This is a common subdev problem related to releasing
> pads from v4l2_device_unregister_subdev() before calling unregister.
> Unregister references pads during unregistering subdev.
> 
> The sd release handler is the right place for releasing all sd resources
> including pads. The release handlers currently release all resources
> except the pads.
> 
> Fix v4l2_device_unregister_subdev() not release pads and release pads
> from the sd_int_op release handlers.
> 
> kernel: [ 4136.715839] general protection fault: 0000 [#1] SMP PTI
> kernel: [ 4136.715847] CPU: 2 PID: 1972 Comm: bash Not tainted 5.3.0-rc2+ #4
> kernel: [ 4136.715850] Hardware name: Dell Inc. OptiPlex 790/0HY9JP, BIOS A18 09/24/2013
> kernel: [ 4136.715858] RIP: 0010:media_gobj_destroy.part.16+0x1f/0x60
> kernel: [ 4136.715863] Code: ff 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 55 48 89 fe 48 89 e5 53 48 89 fb 48 c7 c7 00 7f cf b0 e8 24 fa ff ff 48 8b 03 <48> 83 80 a0 00 00 00 01 48 8b 43 18 48 8b 53 10 48 89 42 08 48 89
> kernel: [ 4136.715866] RSP: 0018:ffff9b2248fe3cb0 EFLAGS: 00010246
> kernel: [ 4136.715870] RAX: bcf2bfbfa0d63c2f RBX: ffff88c3eb37e9c0 RCX: 00000000802a0018
> kernel: [ 4136.715873] RDX: ffff88c3e4f6a078 RSI: ffff88c3eb37e9c0 RDI: ffffffffb0cf7f00
> kernel: [ 4136.715876] RBP: ffff9b2248fe3cb8 R08: 0000000001000002 R09: ffffffffb0492b00
> kernel: [ 4136.715879] R10: ffff9b2248fe3c28 R11: 0000000000000001 R12: 0000000000000038
> kernel: [ 4136.715881] R13: ffffffffc09a1628 R14: ffff88c3e4f6a028 R15: fffffffffffffff2
> kernel: [ 4136.715885] FS:  00007f8389647740(0000) GS:ffff88c465500000(0000) knlGS:0000000000000000
> kernel: [ 4136.715888] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> kernel: [ 4136.715891] CR2: 000055d008f80fd8 CR3: 00000001996ec005 CR4: 00000000000606e0
> kernel: [ 4136.715894] Call Trace:
> kernel: [ 4136.715903]  media_gobj_destroy+0x14/0x20
> kernel: [ 4136.715908]  __media_device_unregister_entity+0xb3/0xe0
> kernel: [ 4136.715915]  media_device_unregister_entity+0x30/0x40
> kernel: [ 4136.715920]  v4l2_device_unregister_subdev+0xa8/0xe0
> kernel: [ 4136.715928]  vimc_ent_sd_unregister+0x1e/0x30 [vimc]
> kernel: [ 4136.715933]  vimc_sen_rm+0x16/0x20 [vimc]
> kernel: [ 4136.715938]  vimc_remove+0x3e/0xa0 [vimc]
> kernel: [ 4136.715945]  platform_drv_remove+0x25/0x50
> kernel: [ 4136.715951]  device_release_driver_internal+0xe0/0x1b0
> kernel: [ 4136.715956]  device_driver_detach+0x14/0x20
> kernel: [ 4136.715960]  unbind_store+0xd1/0x130
> kernel: [ 4136.715965]  drv_attr_store+0x27/0x40
> kernel: [ 4136.715971]  sysfs_kf_write+0x48/0x60
> kernel: [ 4136.715976]  kernfs_fop_write+0x128/0x1b0
> kernel: [ 4136.715982]  __vfs_write+0x1b/0x40
> kernel: [ 4136.715987]  vfs_write+0xc3/0x1d0
> kernel: [ 4136.715993]  ksys_write+0xaa/0xe0
> kernel: [ 4136.715999]  __x64_sys_write+0x1a/0x20
> kernel: [ 4136.716005]  do_syscall_64+0x5a/0x130
> kernel: [ 4136.716010]  entry_SYSCALL_64_after_hwframe+0x4
> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Acked-by: Helen Koike <helen.koike@collabora.com>

> ---
>  drivers/media/platform/vimc/vimc-common.c  | 3 +--
>  drivers/media/platform/vimc/vimc-debayer.c | 1 +
>  drivers/media/platform/vimc/vimc-scaler.c  | 1 +
>  drivers/media/platform/vimc/vimc-sensor.c  | 1 +
>  4 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/vimc/vimc-common.c b/drivers/media/platform/vimc/vimc-common.c
> index 7e1ae0b12f1e..a3120f4f7a90 100644
> --- a/drivers/media/platform/vimc/vimc-common.c
> +++ b/drivers/media/platform/vimc/vimc-common.c
> @@ -375,7 +375,7 @@ int vimc_ent_sd_register(struct vimc_ent_device *ved,
>  {
>  	int ret;
>  
> -	/* Allocate the pads */
> +	/* Allocate the pads. Should be released from the sd_int_op release */
>  	ved->pads = vimc_pads_init(num_pads, pads_flag);
>  	if (IS_ERR(ved->pads))
>  		return PTR_ERR(ved->pads);
> @@ -424,7 +424,6 @@ EXPORT_SYMBOL_GPL(vimc_ent_sd_register);
>  void vimc_ent_sd_unregister(struct vimc_ent_device *ved, struct v4l2_subdev *sd)
>  {
>  	media_entity_cleanup(ved->ent);
> -	vimc_pads_cleanup(ved->pads);
>  	v4l2_device_unregister_subdev(sd);
>  }
>  EXPORT_SYMBOL_GPL(vimc_ent_sd_unregister);
> diff --git a/drivers/media/platform/vimc/vimc-debayer.c b/drivers/media/platform/vimc/vimc-debayer.c
> index 00850f2501ad..b38b55f51a24 100644
> --- a/drivers/media/platform/vimc/vimc-debayer.c
> +++ b/drivers/media/platform/vimc/vimc-debayer.c
> @@ -482,6 +482,7 @@ static void vimc_deb_release(struct v4l2_subdev *sd)
>  	struct vimc_deb_device *vdeb =
>  				container_of(sd, struct vimc_deb_device, sd);
>  
> +	vimc_pads_cleanup(vdeb->ved.pads);
>  	kfree(vdeb);
>  }
>  
> diff --git a/drivers/media/platform/vimc/vimc-scaler.c b/drivers/media/platform/vimc/vimc-scaler.c
> index 28a947950a0b..05db5070e268 100644
> --- a/drivers/media/platform/vimc/vimc-scaler.c
> +++ b/drivers/media/platform/vimc/vimc-scaler.c
> @@ -338,6 +338,7 @@ static void vimc_sca_release(struct v4l2_subdev *sd)
>  	struct vimc_sca_device *vsca =
>  				container_of(sd, struct vimc_sca_device, sd);
>  
> +	vimc_pads_cleanup(vsca->ved.pads);
>  	kfree(vsca);
>  }
>  
> diff --git a/drivers/media/platform/vimc/vimc-sensor.c b/drivers/media/platform/vimc/vimc-sensor.c
> index 1f15637ca8bb..46dc6a535abe 100644
> --- a/drivers/media/platform/vimc/vimc-sensor.c
> +++ b/drivers/media/platform/vimc/vimc-sensor.c
> @@ -291,6 +291,7 @@ static void vimc_sen_release(struct v4l2_subdev *sd)
>  
>  	v4l2_ctrl_handler_free(&vsen->hdl);
>  	tpg_free(&vsen->tpg);
> +	vimc_pads_cleanup(vsen->ved.pads);
>  	kfree(vsen);
>  }
>  
>