[PATCH v2 0/5] staging: most: dim2: replace BUG_ON() with graceful error handling

[PATCH v2 0/5] staging: most: dim2: replace BUG_ON() with graceful error handling

[grondon]

From: Gabriel Rondon <grondon@gmail.com>

Replace all BUG_ON() calls in dim2.c with proper error handling that
returns appropriate error codes instead of panicking the kernel.

BUG_ON() is deprecated per Documentation/process/deprecated.rst.

Changes in v2:
- Split into one patch per function as requested by Greg KH

Gabriel Rondon (5):
  staging: most: dim2: replace BUG_ON() in try_start_dim_transfer()
  staging: most: dim2: replace BUG_ON() in service_done_flag()
  staging: most: dim2: replace BUG_ON() in configure_channel()
  staging: most: dim2: replace BUG_ON() in enqueue()
  staging: most: dim2: replace BUG_ON() in poison_channel()

 drivers/staging/most/dim2/dim2.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

-- 
2.33.0

[PATCH v2 1/5] staging: most: dim2: replace BUG_ON() in try_start_dim_transfer()

[grondon]

From: Gabriel Rondon <grondon@gmail.com>

Replace BUG_ON() calls with graceful error handling.

For the null/uninitialized channel checks, return -EINVAL instead of
crashing the kernel. For the zero bus_address check, release the
spinlock and return -EFAULT.

BUG_ON() is deprecated as it crashes the entire kernel on assertion
failure (see Documentation/process/deprecated.rst).

Signed-off-by: Gabriel Rondon <grondon@gmail.com>
---
 drivers/staging/most/dim2/dim2.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
index 66617e89e..48315f8cd 100644
--- a/drivers/staging/most/dim2/dim2.c
+++ b/drivers/staging/most/dim2/dim2.c
@@ -165,8 +165,8 @@ 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 || !hdm_ch->is_initialized)
+		return -EINVAL;
 
 	spin_lock_irqsave(&dim_lock, flags);
 	if (list_empty(head)) {
@@ -187,7 +187,10 @@ 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 -EFAULT;
+	}
 	if (!dim_enqueue_buffer(&hdm_ch->ch, mbo->bus_address, buf_size)) {
 		list_del(head->next);
 		spin_unlock_irqrestore(&dim_lock, flags);
-- 
2.33.0

[PATCH v2 2/5] staging: most: dim2: replace BUG_ON() in service_done_flag()

[grondon]

From: Gabriel Rondon <grondon@gmail.com>

Replace BUG_ON() calls with an early return since the function returns
void.

BUG_ON() is deprecated as it crashes the entire kernel on assertion
failure (see Documentation/process/deprecated.rst).

Signed-off-by: Gabriel Rondon <grondon@gmail.com>
---
 drivers/staging/most/dim2/dim2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
index 48315f8cd..b820c3647 100644
--- a/drivers/staging/most/dim2/dim2.c
+++ b/drivers/staging/most/dim2/dim2.c
@@ -271,8 +271,8 @@ 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);
 
-- 
2.33.0

[PATCH v2 3/5] staging: most: dim2: replace BUG_ON() in configure_channel()

[grondon]

From: Gabriel Rondon <grondon@gmail.com>

Replace BUG_ON() range check on ch_idx with a return of -EINVAL.

BUG_ON() is deprecated as it crashes the entire kernel on assertion
failure (see Documentation/process/deprecated.rst).

Signed-off-by: Gabriel Rondon <grondon@gmail.com>
---
 drivers/staging/most/dim2/dim2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
index b820c3647..0b80f313a 100644
--- a/drivers/staging/most/dim2/dim2.c
+++ b/drivers/staging/most/dim2/dim2.c
@@ -457,7 +457,8 @@ 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;
-- 
2.33.0

[PATCH v2 4/5] staging: most: dim2: replace BUG_ON() in enqueue()

[grondon]

From: Gabriel Rondon <grondon@gmail.com>

Replace BUG_ON() range check on ch_idx with a return of -EINVAL.

BUG_ON() is deprecated as it crashes the entire kernel on assertion
failure (see Documentation/process/deprecated.rst).

Signed-off-by: Gabriel Rondon <grondon@gmail.com>
---
 drivers/staging/most/dim2/dim2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
index 0b80f313a..23230a32c 100644
--- a/drivers/staging/most/dim2/dim2.c
+++ b/drivers/staging/most/dim2/dim2.c
@@ -570,7 +570,8 @@ 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;
-- 
2.33.0

[PATCH v2 5/5] staging: most: dim2: replace BUG_ON() in poison_channel()

[grondon]

From: Gabriel Rondon <grondon@gmail.com>

Replace BUG_ON() range check on ch_idx with a return of -EINVAL.

BUG_ON() is deprecated as it crashes the entire kernel on assertion
failure (see Documentation/process/deprecated.rst).

Signed-off-by: Gabriel Rondon <grondon@gmail.com>
---
 drivers/staging/most/dim2/dim2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
index 23230a32c..7953d4626 100644
--- a/drivers/staging/most/dim2/dim2.c
+++ b/drivers/staging/most/dim2/dim2.c
@@ -647,7 +647,8 @@ 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;
-- 
2.33.0

Re: [PATCH v2 2/5] staging: most: dim2: replace BUG_ON() in service_done_flag()

[Dan Carpenter]

On Mon, Mar 30, 2026 at 07:22:52PM +0100, grondon@gmail.com wrote:
> From: Gabriel Rondon <grondon@gmail.com>
> 
> Replace BUG_ON() calls with an early return since the function returns
> void.
> 
> BUG_ON() is deprecated as it crashes the entire kernel on assertion
> failure (see Documentation/process/deprecated.rst).
> 
> Signed-off-by: Gabriel Rondon <grondon@gmail.com>
> ---
>  drivers/staging/most/dim2/dim2.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
> index 48315f8cd..b820c3647 100644
> --- a/drivers/staging/most/dim2/dim2.c
> +++ b/drivers/staging/most/dim2/dim2.c
> @@ -271,8 +271,8 @@ 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)

hdm_ch can't be NULL.  It's a pointer to the middle of a struct plus
an offset.

regards,
dan carpenter

> +		return;
>  
>  	spin_lock_irqsave(&dim_lock, flags);
>  
> -- 
> 2.33.0
> 

Re: [PATCH v2 2/5] staging: most: dim2: replace BUG_ON() in service_done_flag()

[grondon]

From: Gabriel Rondon <grondon@gmail.com>

On Tue, 31 Mar 2026 13:55:43 +0300, Dan Carpenter wrote:
> hdm_ch can't be NULL.  It's a pointer to the middle of a struct plus
> an offset.

You're right, the NULL check is unnecessary here. Will send a fix
removing the !hdm_ch check and keeping only !hdm_ch->is_initialized.

Thanks,
Gabriel

Re: [PATCH v2 2/5] staging: most: dim2: replace BUG_ON() in service_done_flag()

[Dan Carpenter]

On Tue, Mar 31, 2026 at 05:44:29PM +0100, grondon@gmail.com wrote:
> From: Gabriel Rondon <grondon@gmail.com>
> 
> On Tue, 31 Mar 2026 13:55:43 +0300, Dan Carpenter wrote:
> > hdm_ch can't be NULL.  It's a pointer to the middle of a struct plus
> > an offset.
> 
> You're right, the NULL check is unnecessary here. Will send a fix
> removing the !hdm_ch check and keeping only !hdm_ch->is_initialized.

Check them all, right?  Maybe the others are similar?

regards,
dan carpenter

Re: [PATCH v2 2/5] staging: most: dim2: replace BUG_ON() in service_done_flag()

[grondon]

From: Gabriel Rondon <grondon@gmail.com>

On Tue, 31 Mar 2026 22:40:00 +0300, Dan Carpenter wrote:
> Check them all, right?  Maybe the others are similar?

Checked. Patches 3/5 through 5/5 (configure_channel, enqueue,
poison_channel) only check ch_idx range, no hdm_ch NULL check — those
are fine.

Patch 1/5 (try_start_dim_transfer) does have the same unnecessary
!hdm_ch check. hdm_ch is a parameter there, but it's already
dereferenced on the line above (head = &hdm_ch->pending_list), so a
NULL check after that is dead code. Will send a fix for that one too.

Thanks,
Gabriel