[PATCH] staging: most: dim2: replace BUG_ON with WARN_ON_ONCE and error handling

[Yuvraj Singh Chauhan <ysinghcin@gmail.com>]

Replace BUG_ON() with WARN_ON_ONCE() and proper error handling in the
DIM2 driver. BUG_ON() crashes the entire kernel, which is excessive for
conditions that can be handled by returning error codes or exiting the
function early.

Changes made:

- try_start_dim_transfer(): Check hdm_ch validity and initialization
  status, returning -EINVAL on failure. Check mbo->bus_address validity,
  releasing the spinlock and returning -EFAULT if zero.

- service_done_flag(): Check hdm_ch validity and initialization status,
  returning early if checks fail.

- configure_channel(), enqueue(), poison_channel(): Validate ch_idx
  bounds and return -EINVAL if out of range.

WARN_ON_ONCE() is used instead of WARN_ON() to prevent log flooding if
the condition triggers repeatedly.

Signed-off-by: Yuvraj Singh Chauhan <ysinghcin@gmail.com>
---
 drivers/staging/most/dim2/dim2.c | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
index dad2abe6c0c9..58b09fa581e0 100644
--- a/drivers/staging/most/dim2/dim2.c
+++ b/drivers/staging/most/dim2/dim2.c
@@ -166,8 +166,10 @@ 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 (WARN_ON_ONCE(!hdm_ch))
+		return -EINVAL;
+	if (WARN_ON_ONCE(!hdm_ch->is_initialized))
+		return -EINVAL;
 
 	spin_lock_irqsave(&dim_lock, flags);
 	if (list_empty(head)) {
@@ -188,7 +190,10 @@ static int try_start_dim_transfer(struct hdm_channel *hdm_ch)
 		return -EAGAIN;
 	}
 
-	BUG_ON(mbo->bus_address == 0);
+	if (WARN_ON_ONCE(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);
@@ -269,8 +274,10 @@ 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 (WARN_ON_ONCE(!hdm_ch))
+		return;
+	if (WARN_ON_ONCE(!hdm_ch->is_initialized))
+		return;
 
 	spin_lock_irqsave(&dim_lock, flags);
 
@@ -455,7 +462,8 @@ 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 (WARN_ON_ONCE(ch_idx < 0 || ch_idx >= DMA_CHANNELS))
+		return -EINVAL;
 
 	if (hdm_ch->is_initialized)
 		return -EPERM;
@@ -567,7 +575,8 @@ 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 (WARN_ON_ONCE(ch_idx < 0 || ch_idx >= DMA_CHANNELS))
+		return -EINVAL;
 
 	if (!hdm_ch->is_initialized)
 		return -EPERM;
@@ -643,7 +652,8 @@ 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 (WARN_ON_ONCE(ch_idx < 0 || ch_idx >= DMA_CHANNELS))
+		return -EINVAL;
 
 	if (!hdm_ch->is_initialized)
 		return -EPERM;

base-commit: 05f7e89ab9731565d8a62e3b5d1ec206485eeb0b
-- 
2.43.0