[PATCH] staging: most: dim2: replace BUG_ON() with error handling

[PATCH] staging: most: dim2: replace BUG_ON() with error handling

[Mark Adamenko]

Replace BUG_ON() calls with error handling to avoid unnecessary kernel
crashes.

Signed-off-by: Mark Adamenko <marusik.adamenko@gmail.com>
---
 drivers/staging/most/dim2/dim2.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
index 8d649d920433..cec9d19e1cde 100644
--- a/drivers/staging/most/dim2/dim2.c
+++ b/drivers/staging/most/dim2/dim2.c
@@ -168,8 +168,10 @@ static int try_start_dim_transfer(struct hdm_channel *hdm_ch)
 	unsigned long flags;
 	struct dim_ch_state st;
 
-	BUG_ON(!hdm_ch);
-	BUG_ON(!hdm_ch->is_initialized);
+	if (!hdm_ch)
+		return -EINVAL;
+	if (!hdm_ch->is_initialized)
+		return -EINVAL;
 
 	spin_lock_irqsave(&dim_lock, flags);
 	if (list_empty(head)) {
@@ -190,7 +192,11 @@ static int try_start_dim_transfer(struct hdm_channel *hdm_ch)
 		return -EAGAIN;
 	}
 
-	BUG_ON(mbo->bus_address == 0);
+	if (mbo->bus_address == 0) {
+		spin_unlock_irqrestore(&dim_lock, flags);
+		return -EINVAL;
+	}
+
 	if (!dim_enqueue_buffer(&hdm_ch->ch, mbo->bus_address, buf_size)) {
 		list_del(head->next);
 		spin_unlock_irqrestore(&dim_lock, flags);
@@ -271,8 +277,8 @@ static void service_done_flag(struct dim2_hdm *dev, int ch_idx)
 	unsigned long flags;
 	u8 *data;
 
-	BUG_ON(!hdm_ch);
-	BUG_ON(!hdm_ch->is_initialized);
+	if (!hdm_ch || !hdm_ch->is_initialized)
+		return;
 
 	spin_lock_irqsave(&dim_lock, flags);
 
@@ -457,7 +463,8 @@ static int configure_channel(struct most_interface *most_iface, int ch_idx,
 	int const ch_addr = ch_idx * 2 + 2;
 	struct hdm_channel *const hdm_ch = dev->hch + ch_idx;
 
-	BUG_ON(ch_idx < 0 || ch_idx >= DMA_CHANNELS);
+	if (ch_idx < 0 || ch_idx >= DMA_CHANNELS)
+		return -EINVAL;
 
 	if (hdm_ch->is_initialized)
 		return -EPERM;
@@ -569,7 +576,8 @@ static int enqueue(struct most_interface *most_iface, int ch_idx,
 	struct hdm_channel *hdm_ch = dev->hch + ch_idx;
 	unsigned long flags;
 
-	BUG_ON(ch_idx < 0 || ch_idx >= DMA_CHANNELS);
+	if (ch_idx < 0 || ch_idx >= DMA_CHANNELS)
+		return -EINVAL;
 
 	if (!hdm_ch->is_initialized)
 		return -EPERM;
@@ -645,7 +653,8 @@ static int poison_channel(struct most_interface *most_iface, int ch_idx)
 	u8 hal_ret;
 	int ret = 0;
 
-	BUG_ON(ch_idx < 0 || ch_idx >= DMA_CHANNELS);
+	if (ch_idx < 0 || ch_idx >= DMA_CHANNELS)
+		return -EINVAL;
 
 	if (!hdm_ch->is_initialized)
 		return -EPERM;
-- 
2.53.0

Re: [PATCH] staging: most: dim2: replace BUG_ON() with error handling

[Greg KH]

On Wed, Mar 04, 2026 at 06:01:48PM -0800, Mark Adamenko wrote:
> Replace BUG_ON() calls with error handling to avoid unnecessary kernel
> crashes.
> 
> Signed-off-by: Mark Adamenko <marusik.adamenko@gmail.com>
> ---
>  drivers/staging/most/dim2/dim2.c | 25 +++++++++++++++++--------
>  1 file changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
> index 8d649d920433..cec9d19e1cde 100644
> --- a/drivers/staging/most/dim2/dim2.c
> +++ b/drivers/staging/most/dim2/dim2.c
> @@ -168,8 +168,10 @@ static int try_start_dim_transfer(struct hdm_channel *hdm_ch)
>  	unsigned long flags;
>  	struct dim_ch_state st;
>  
> -	BUG_ON(!hdm_ch);
> -	BUG_ON(!hdm_ch->is_initialized);
> +	if (!hdm_ch)
> +		return -EINVAL;

Can this ever happen?  If not, why is this even checked?  (hint, I do
not think it ever can)

> +	if (!hdm_ch->is_initialized)
> +		return -EINVAL;

Same here, are you sure this can happen?  And can the caller handle an
error?  At first glance, I do not think it can.  So be careful with
this.

You can't just blindly replace BUG_ON() with tests, please verify if
they are needed, and if so, how to handle the error correctly.

thanks,

greg k-h