[PATCH v2] media: nuvoton: npcm-video: Fix sleeping in atomic context

From: Marvin Lin
Date: Wed Oct 11 2023 - 03:30:36 EST


Change to use mutex instead of spinlock for buffer list lock to fix
sleeping in atomic context warnings reported by the Smatch tool.

Fixes: 70721089985c ("media: nuvoton: Add driver for NPCM video capture and encoding engine")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Marvin Lin <milkfafa@xxxxxxxxx>
---
drivers/media/platform/nuvoton/npcm-video.c | 30 +++++++++------------
1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/drivers/media/platform/nuvoton/npcm-video.c b/drivers/media/platform/nuvoton/npcm-video.c
index b9e6782f59b4..ea32d9588bb5 100644
--- a/drivers/media/platform/nuvoton/npcm-video.c
+++ b/drivers/media/platform/nuvoton/npcm-video.c
@@ -26,7 +26,6 @@
#include <linux/regmap.h>
#include <linux/reset.h>
#include <linux/sched.h>
-#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/v4l2-controls.h>
#include <linux/videodev2.h>
@@ -120,7 +119,7 @@ struct npcm_video {
struct mutex video_lock; /* v4l2 and videobuf2 lock */

struct list_head buffers;
- spinlock_t lock; /* buffer list lock */
+ struct mutex buffer_lock; /* buffer list lock */
unsigned long flags;
unsigned int sequence;

@@ -782,7 +781,6 @@ static int npcm_video_start_frame(struct npcm_video *video)
{
struct npcm_video_buffer *buf;
struct regmap *vcd = video->vcd_regmap;
- unsigned long flags;
unsigned int val;
int ret;

@@ -798,17 +796,17 @@ static int npcm_video_start_frame(struct npcm_video *video)
return -EBUSY;
}

- spin_lock_irqsave(&video->lock, flags);
+ mutex_lock(&video->buffer_lock);
buf = list_first_entry_or_null(&video->buffers,
struct npcm_video_buffer, link);
if (!buf) {
- spin_unlock_irqrestore(&video->lock, flags);
+ mutex_unlock(&video->buffer_lock);
dev_dbg(video->dev, "No empty buffers; skip capture frame\n");
return 0;
}

set_bit(VIDEO_CAPTURING, &video->flags);
- spin_unlock_irqrestore(&video->lock, flags);
+ mutex_unlock(&video->buffer_lock);

npcm_video_vcd_state_machine_reset(video);

@@ -834,14 +832,13 @@ static void npcm_video_bufs_done(struct npcm_video *video,
enum vb2_buffer_state state)
{
struct npcm_video_buffer *buf;
- unsigned long flags;

- spin_lock_irqsave(&video->lock, flags);
+ mutex_lock(&video->buffer_lock);
list_for_each_entry(buf, &video->buffers, link)
vb2_buffer_done(&buf->vb.vb2_buf, state);

INIT_LIST_HEAD(&video->buffers);
- spin_unlock_irqrestore(&video->lock, flags);
+ mutex_unlock(&video->buffer_lock);
}

static void npcm_video_get_diff_rect(struct npcm_video *video, unsigned int index)
@@ -1071,12 +1068,12 @@ static irqreturn_t npcm_video_irq(int irq, void *arg)

if (status & VCD_STAT_DONE) {
regmap_write(vcd, VCD_INTE, 0);
- spin_lock(&video->lock);
+ mutex_lock(&video->buffer_lock);
clear_bit(VIDEO_CAPTURING, &video->flags);
buf = list_first_entry_or_null(&video->buffers,
struct npcm_video_buffer, link);
if (!buf) {
- spin_unlock(&video->lock);
+ mutex_unlock(&video->buffer_lock);
return IRQ_NONE;
}

@@ -1093,7 +1090,7 @@ static irqreturn_t npcm_video_irq(int irq, void *arg)
size = npcm_video_hextile(video, index, dma_addr, addr);
break;
default:
- spin_unlock(&video->lock);
+ mutex_unlock(&video->buffer_lock);
return IRQ_NONE;
}

@@ -1104,7 +1101,7 @@ static irqreturn_t npcm_video_irq(int irq, void *arg)

vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
list_del(&buf->link);
- spin_unlock(&video->lock);
+ mutex_unlock(&video->buffer_lock);

if (npcm_video_start_frame(video))
dev_err(video->dev, "Failed to capture next frame\n");
@@ -1508,13 +1505,12 @@ static void npcm_video_buf_queue(struct vb2_buffer *vb)
struct npcm_video *video = vb2_get_drv_priv(vb->vb2_queue);
struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
struct npcm_video_buffer *nvb = to_npcm_video_buffer(vbuf);
- unsigned long flags;
bool empty;

- spin_lock_irqsave(&video->lock, flags);
+ mutex_lock(&video->buffer_lock);
empty = list_empty(&video->buffers);
list_add_tail(&nvb->link, &video->buffers);
- spin_unlock_irqrestore(&video->lock, flags);
+ mutex_unlock(&video->buffer_lock);

if (test_bit(VIDEO_STREAMING, &video->flags) &&
!test_bit(VIDEO_CAPTURING, &video->flags) && empty) {
@@ -1744,8 +1740,8 @@ static int npcm_video_probe(struct platform_device *pdev)
return -ENOMEM;

video->dev = &pdev->dev;
- spin_lock_init(&video->lock);
mutex_init(&video->video_lock);
+ mutex_init(&video->buffer_lock);
INIT_LIST_HEAD(&video->buffers);

regs = devm_platform_ioremap_resource(pdev, 0);
--
2.34.1