The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x a5844227e0f030d2af2d85d4aed10c5eca6ca176 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2026010509-angelic-pavement-9017@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a5844227e0f030d2af2d85d4aed10c5eca6ca176 Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai wenst@chromium.org Date: Wed, 20 Aug 2025 15:54:05 +0800 Subject: [PATCH] media: mediatek: vcodec: Use spinlock for context list protection lock

Previously a mutex was added to protect the encoder and decoder context lists from unexpected changes originating from the SCP IP block, causing the context pointer to go invalid, resulting in a NULL pointer dereference in the IPI handler.

Turns out on the MT8173, the VPU IPI handler is called from hard IRQ context. This causes a big warning from the scheduler. This was first reported downstream on the ChromeOS kernels, but is also reproducible on mainline using Fluster with the FFmpeg v4l2m2m decoders. Even though the actual capture format is not supported, the affected code paths are triggered.

Since this lock just protects the context list and operations on it are very fast, it should be OK to switch to a spinlock.

Fixes: 6467cda18c9f ("media: mediatek: vcodec: adding lock to protect decoder context list") Fixes: afaaf3a0f647 ("media: mediatek: vcodec: adding lock to protect encoder context list") Cc: Yunfei Dong yunfei.dong@mediatek.com Cc: stable@vger.kernel.org Signed-off-by: Chen-Yu Tsai wenst@chromium.org Reviewed-by: Fei Shao fshao@chromium.org Reviewed-by: Tomasz Figa tfiga@chromium.org Signed-off-by: Nicolas Dufresne nicolas.dufresne@collabora.com Signed-off-by: Hans Verkuil hverkuil+cisco@kernel.org

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 d7027d600208..223fb2294894 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 @@ -47,30 +47,32 @@ static void mtk_vcodec_vpu_reset_dec_handler(void *priv) { struct mtk_vcodec_dec_dev *dev = priv; struct mtk_vcodec_dec_ctx *ctx; + unsigned long flags;

dev_err(&dev->plat_dev->dev, "Watchdog timeout!!");

- mutex_lock(&dev->dev_ctx_lock); + spin_lock_irqsave(&dev->dev_ctx_lock, flags); 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_ctx_lock); + spin_unlock_irqrestore(&dev->dev_ctx_lock, flags); }

static void mtk_vcodec_vpu_reset_enc_handler(void *priv) { struct mtk_vcodec_enc_dev *dev = priv; struct mtk_vcodec_enc_ctx *ctx; + unsigned long flags;

dev_err(&dev->plat_dev->dev, "Watchdog timeout!!");

- mutex_lock(&dev->dev_ctx_lock); + spin_lock_irqsave(&dev->dev_ctx_lock, flags); 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_ctx_lock); + spin_unlock_irqrestore(&dev->dev_ctx_lock, flags); }

static const struct mtk_vcodec_fw_ops mtk_vcodec_vpu_msg = { 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 46d176e6de63..3b81fae9f913 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 @@ -198,6 +198,7 @@ static int fops_vcodec_open(struct file *file) struct mtk_vcodec_dec_ctx *ctx = NULL; int ret = 0, i, hw_count; struct vb2_queue *src_vq; + unsigned long flags;

ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) @@ -267,9 +268,9 @@ static int fops_vcodec_open(struct file *file)

ctx->dev->vdec_pdata->init_vdec_params(ctx);

- mutex_lock(&dev->dev_ctx_lock); + spin_lock_irqsave(&dev->dev_ctx_lock, flags); list_add(&ctx->list, &dev->ctx_list); - mutex_unlock(&dev->dev_ctx_lock); + spin_unlock_irqrestore(&dev->dev_ctx_lock, flags); mtk_vcodec_dbgfs_create(ctx);

mutex_unlock(&dev->dev_mutex); @@ -294,6 +295,7 @@ static int fops_vcodec_release(struct file *file) { struct mtk_vcodec_dec_dev *dev = video_drvdata(file); struct mtk_vcodec_dec_ctx *ctx = file_to_dec_ctx(file); + unsigned long flags;

mtk_v4l2_vdec_dbg(0, ctx, "[%d] decoder", ctx->id); mutex_lock(&dev->dev_mutex); @@ -312,9 +314,9 @@ 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); + spin_lock_irqsave(&dev->dev_ctx_lock, flags); list_del_init(&ctx->list); - mutex_unlock(&dev->dev_ctx_lock); + spin_unlock_irqrestore(&dev->dev_ctx_lock, flags); kfree(ctx); mutex_unlock(&dev->dev_mutex); return 0; @@ -407,7 +409,7 @@ 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->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 d047d7c580fb..9d68808e8f9c 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 @@ -285,7 +285,7 @@ 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; + spinlock_t 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 145958206e38..40b97f114cf6 100644 --- a/drivers/media/platform/mediatek/vcodec/decoder/vdec_vpu_if.c +++ b/drivers/media/platform/mediatek/vcodec/decoder/vdec_vpu_if.c @@ -75,16 +75,17 @@ static void handle_get_param_msg_ack(const struct vdec_vpu_ipi_get_param_ack *ms static bool vpu_dec_check_ap_inst(struct mtk_vcodec_dec_dev *dec_dev, struct vdec_vpu_inst *vpu) { struct mtk_vcodec_dec_ctx *ctx; + unsigned long flags; int ret = false;

- mutex_lock(&dec_dev->dev_ctx_lock); + spin_lock_irqsave(&dec_dev->dev_ctx_lock, flags); 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); + spin_unlock_irqrestore(&dec_dev->dev_ctx_lock, flags);

return ret; } diff --git a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c index fb1c3bdc2dae..82b8ff38e8f1 100644 --- a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c +++ b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c @@ -117,6 +117,7 @@ static int fops_vcodec_open(struct file *file) struct mtk_vcodec_enc_ctx *ctx = NULL; int ret = 0; struct vb2_queue *src_vq; + unsigned long flags;

ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) @@ -176,9 +177,9 @@ static int fops_vcodec_open(struct file *file) mtk_v4l2_venc_dbg(2, ctx, "Create instance [%d]@%p m2m_ctx=%p ", ctx->id, ctx, ctx->m2m_ctx);

- mutex_lock(&dev->dev_ctx_lock); + spin_lock_irqsave(&dev->dev_ctx_lock, flags); list_add(&ctx->list, &dev->ctx_list); - mutex_unlock(&dev->dev_ctx_lock); + spin_unlock_irqrestore(&dev->dev_ctx_lock, flags);

mutex_unlock(&dev->dev_mutex); mtk_v4l2_venc_dbg(0, ctx, "%s encoder [%d]", dev_name(&dev->plat_dev->dev), @@ -203,6 +204,7 @@ static int fops_vcodec_release(struct file *file) { struct mtk_vcodec_enc_dev *dev = video_drvdata(file); struct mtk_vcodec_enc_ctx *ctx = file_to_enc_ctx(file); + unsigned long flags;

mtk_v4l2_venc_dbg(1, ctx, "[%d] encoder", ctx->id); mutex_lock(&dev->dev_mutex); @@ -213,9 +215,9 @@ static int fops_vcodec_release(struct file *file) v4l2_fh_exit(&ctx->fh); v4l2_ctrl_handler_free(&ctx->ctrl_hdl);

- mutex_lock(&dev->dev_ctx_lock); + spin_lock_irqsave(&dev->dev_ctx_lock, flags); list_del_init(&ctx->list); - mutex_unlock(&dev->dev_ctx_lock); + spin_unlock_irqrestore(&dev->dev_ctx_lock, flags); kfree(ctx); mutex_unlock(&dev->dev_mutex); return 0; @@ -297,7 +299,7 @@ static int mtk_vcodec_probe(struct platform_device *pdev)

mutex_init(&dev->enc_mutex); mutex_init(&dev->dev_mutex); - mutex_init(&dev->dev_ctx_lock); + spin_lock_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/encoder/mtk_vcodec_enc_drv.h b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.h index 5b304a551236..0cddfa13594f 100644 --- a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.h +++ b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.h @@ -206,7 +206,7 @@ struct mtk_vcodec_enc_dev { /* encoder hardware mutex lock */ struct mutex enc_mutex; struct mutex dev_mutex; - struct mutex dev_ctx_lock; + spinlock_t dev_ctx_lock; struct workqueue_struct *encode_workqueue;

int enc_irq; diff --git a/drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c b/drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c index 51bb7ee141b9..3c229b1f6b21 100644 --- a/drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c +++ b/drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c @@ -45,16 +45,17 @@ static void handle_enc_encode_msg(struct venc_vpu_inst *vpu, const void *data) static bool vpu_enc_check_ap_inst(struct mtk_vcodec_enc_dev *enc_dev, struct venc_vpu_inst *vpu) { struct mtk_vcodec_enc_ctx *ctx; + unsigned long flags; int ret = false;

- mutex_lock(&enc_dev->dev_ctx_lock); + spin_lock_irqsave(&enc_dev->dev_ctx_lock, flags); list_for_each_entry(ctx, &enc_dev->ctx_list, list) { if (!IS_ERR_OR_NULL(ctx) && ctx->vpu_inst == vpu) { ret = true; break; } } - mutex_unlock(&enc_dev->dev_ctx_lock); + spin_unlock_irqrestore(&enc_dev->dev_ctx_lock, flags);

return ret; }