Re: [PATCH v3,1/2] media: mediatek: vcodec: adding lock to protect decoder context list

[Nicolas Dufresne <nicolas.dufresne@collabora.com>]

Hi Yunfei,

Le jeudi 22 février 2024 à 17:26 +0800, Yunfei Dong a écrit :
> The ctx_list will be deleted when scp getting unexpected behavior, then the
> ctx_list->next will be NULL, the kernel driver maybe access NULL pointer in
> function vpu_dec_ipi_handler when going through each context, then reboot.
> 
> Need to add lock to protect the ctx_list to make sure the ctx_list->next isn't
> NULL pointer.
> 
> Hardware name: Google juniper sku16 board (DT)
> pstate: 20400005 (nzCv daif +PAN -UAO -TCO BTYPE=--)
> pc : vpu_dec_ipi_handler+0x58/0x1f8 [mtk_vcodec_dec]
> lr : scp_ipi_handler+0xd0/0x194 [mtk_scp]
> sp : ffffffc0131dbbd0
> x29: ffffffc0131dbbd0 x28: 0000000000000000
> x27: ffffff9bb277f348 x26: ffffff9bb242ad00
> x25: ffffffd2d440d3b8 x24: ffffffd2a13ff1d4
> x23: ffffff9bb7fe85a0 x22: ffffffc0133fbdb0
> x21: 0000000000000010 x20: ffffff9b050ea328
> x19: ffffffc0131dbc08 x18: 0000000000001000
> x17: 0000000000000000 x16: ffffffd2d461c6e0
> x15: 0000000000000242 x14: 000000000000018f
> x13: 000000000000004d x12: 0000000000000000
> x11: 0000000000000001 x10: fffffffffffffff0
> x9 : ffffff9bb6e793a8 x8 : 0000000000000000
> x7 : 0000000000000000 x6 : 000000000000003f
> x5 : 0000000000000040 x4 : fffffffffffffff0
> x3 : 0000000000000020 x2 : ffffff9bb6e79080
> x1 : 0000000000000010 x0 : ffffffc0131dbc08
> Call trace:
> vpu_dec_ipi_handler+0x58/0x1f8 [mtk_vcodec_dec (HASH:6c3f 2)]
> scp_ipi_handler+0xd0/0x194 [mtk_scp (HASH:7046 3)]
> mt8183_scp_irq_handler+0x44/0x88 [mtk_scp (HASH:7046 3)]
> scp_irq_handler+0x48/0x90 [mtk_scp (HASH:7046 3)]
> irq_thread_fn+0x38/0x94
> irq_thread+0x100/0x1c0
> kthread+0x140/0x1fc
> ret_from_fork+0x10/0x30
> Code: 54000088 f94ca50a eb14015f 54000060 (f9400108)
> ---[ end trace ace43ce36cbd5c93 ]---
> Kernel panic - not syncing: Oops: Fatal exception
> SMP: stopping secondary CPUs
> Kernel Offset: 0x12c4000000 from 0xffffffc010000000
> PHYS_OFFSET: 0xffffffe580000000
> CPU features: 0x08240002,2188200c
> Memory Limit: none
> 
> Fixes: 655b86e52eac ("media: mediatek: vcodec: Fix possible invalid memory access for decoder")
> Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>

I've been experiencing this crasher recently, so nice to see you found the
problem.

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>

> ---
>  .../platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c      | 4 ++--
>  .../platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c    | 5 +++++
>  .../platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.h    | 2 ++
>  drivers/media/platform/mediatek/vcodec/decoder/vdec_vpu_if.c | 2 ++
>  4 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
> index 9f6e4b59455da..9a11a2c248045 100644
> --- a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
> +++ b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
> @@ -58,12 +58,12 @@ static void mtk_vcodec_vpu_reset_dec_handler(void *priv)
>  
>  	dev_err(&dev->plat_dev->dev, "Watchdog timeout!!");
>  
> -	mutex_lock(&dev->dev_mutex);
> +	mutex_lock(&dev->dev_ctx_lock);
>  	list_for_each_entry(ctx, &dev->ctx_list, list) {
>  		ctx->state = MTK_STATE_ABORT;
>  		mtk_v4l2_vdec_dbg(0, ctx, "[%d] Change to state MTK_STATE_ABORT", ctx->id);
>  	}
> -	mutex_unlock(&dev->dev_mutex);
> +	mutex_unlock(&dev->dev_ctx_lock);
>  }
>  
>  static void mtk_vcodec_vpu_reset_enc_handler(void *priv)
> diff --git a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c
> index ad9b68380692f..d69c9fe2af6f3 100644
> --- a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c
> +++ b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.c
> @@ -267,7 +267,9 @@ static int fops_vcodec_open(struct file *file)
>  
>  	ctx->dev->vdec_pdata->init_vdec_params(ctx);
>  
> +	mutex_lock(&dev->dev_ctx_lock);
>  	list_add(&ctx->list, &dev->ctx_list);
> +	mutex_unlock(&dev->dev_ctx_lock);
>  	mtk_vcodec_dbgfs_create(ctx);
>  
>  	mutex_unlock(&dev->dev_mutex);
> @@ -310,7 +312,9 @@ static int fops_vcodec_release(struct file *file)
>  	v4l2_ctrl_handler_free(&ctx->ctrl_hdl);
>  
>  	mtk_vcodec_dbgfs_remove(dev, ctx->id);
> +	mutex_lock(&dev->dev_ctx_lock);
>  	list_del_init(&ctx->list);
> +	mutex_unlock(&dev->dev_ctx_lock);
>  	kfree(ctx);
>  	mutex_unlock(&dev->dev_mutex);
>  	return 0;
> @@ -403,6 +407,7 @@ static int mtk_vcodec_probe(struct platform_device *pdev)
>  	for (i = 0; i < MTK_VDEC_HW_MAX; i++)
>  		mutex_init(&dev->dec_mutex[i]);
>  	mutex_init(&dev->dev_mutex);
> +	mutex_init(&dev->dev_ctx_lock);
>  	spin_lock_init(&dev->irqlock);
>  
>  	snprintf(dev->v4l2_dev.name, sizeof(dev->v4l2_dev.name), "%s",
> diff --git a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.h b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.h
> index 849b89dd205c2..85b2c0d3d8bcd 100644
> --- a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.h
> +++ b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv.h
> @@ -241,6 +241,7 @@ struct mtk_vcodec_dec_ctx {
>   *
>   * @dec_mutex: decoder hardware lock
>   * @dev_mutex: video_device lock
> + * @dev_ctx_lock: the lock of context list
>   * @decode_workqueue: decode work queue
>   *
>   * @irqlock: protect data access by irq handler and work thread
> @@ -282,6 +283,7 @@ struct mtk_vcodec_dec_dev {
>  	/* decoder hardware mutex lock */
>  	struct mutex dec_mutex[MTK_VDEC_HW_MAX];
>  	struct mutex dev_mutex;
> +	struct mutex dev_ctx_lock;
>  	struct workqueue_struct *decode_workqueue;
>  
>  	spinlock_t irqlock;
> diff --git a/drivers/media/platform/mediatek/vcodec/decoder/vdec_vpu_if.c b/drivers/media/platform/mediatek/vcodec/decoder/vdec_vpu_if.c
> index 82e57ae983d55..da6be556727bb 100644
> --- a/drivers/media/platform/mediatek/vcodec/decoder/vdec_vpu_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/decoder/vdec_vpu_if.c
> @@ -77,12 +77,14 @@ static bool vpu_dec_check_ap_inst(struct mtk_vcodec_dec_dev *dec_dev, struct vde
>  	struct mtk_vcodec_dec_ctx *ctx;
>  	int ret = false;
>  
> +	mutex_lock(&dec_dev->dev_ctx_lock);
>  	list_for_each_entry(ctx, &dec_dev->ctx_list, list) {
>  		if (!IS_ERR_OR_NULL(ctx) && ctx->vpu_inst == vpu) {
>  			ret = true;
>  			break;
>  		}
>  	}
> +	mutex_unlock(&dec_dev->dev_ctx_lock);
>  
>  	return ret;
>  }