linux-kernel - [PATCH 2/3] staging: most: dim2: replace BUG_ON() with WARN_ON

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Message-Id: <20251021-staging-most-warn-v1-2-4cdd3745bbdc@lukowski.dev>
Date: Tue, 21 Oct 2025 15:16:28 +0300
From: Olle Lukowski <olle@...owski.dev>
To: Parthiban Veerasooran <parthiban.veerasooran@...rochip.com>, 
 Christian Gromm <christian.gromm@...rochip.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org, 
 Olle Lukowski <olle@...owski.dev>
Subject: [PATCH 2/3] staging: most: dim2: replace BUG_ON() with
 WARN_ON_ONCE() and proper error returns

Replace BUG_ON() calls with WARN_ON_ONCE() to prevent unnecessary kernel
panics. Return appropriate error codes (-EINVAL or -EFAULT) instead of
crashing the system.

Signed-off-by: Olle Lukowski <olle@...owski.dev>
---
 drivers/staging/most/dim2/dim2.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/most/dim2/dim2.c b/drivers/staging/most/dim2/dim2.c
index dad2abe6c..a9dc3765b 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 +190,11 @@ 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 +275,10 @@ 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 +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 (WARN_ON_ONCE(ch_idx < 0 || ch_idx >= DMA_CHANNELS))
+		return -EINVAL;
 
 	if (hdm_ch->is_initialized)
 		return -EPERM;
@@ -567,7 +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 (WARN_ON_ONCE(ch_idx < 0 || ch_idx >= DMA_CHANNELS))
+		return -EINVAL;
 
 	if (!hdm_ch->is_initialized)
 		return -EPERM;
@@ -643,7 +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 (WARN_ON_ONCE(ch_idx < 0 || ch_idx >= DMA_CHANNELS))
+		return -EINVAL;
 
 	if (!hdm_ch->is_initialized)
 		return -EPERM;

-- 
2.51.1