media: v4l2-mem2mem: add lock to protect parameter num_rdy

Getting below error when using KCSAN to check the driver. Adding lock to
protect parameter num_rdy when getting the value with function:
v4l2_m2m_num_src_bufs_ready/v4l2_m2m_num_dst_bufs_ready.

kworker/u16:3: [name:report&]BUG: KCSAN: data-race in v4l2_m2m_buf_queue
kworker/u16:3: [name:report&]

kworker/u16:3: [name:report&]read-write to 0xffffff8105f35b94 of 1 bytes by task 20865 on cpu 7:
kworker/u16:3:  v4l2_m2m_buf_queue+0xd8/0x10c

Signed-off-by: Pina Chen <pina.chen@mediatek.com>
Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index bb9de6a899e07149bbe8affce2af84cf99e08f3d..d6c8eb2b52019dcd0b66f8ac1926b095d0781d48 100644 (file)
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -593,7 +593,14 @@ void v4l2_m2m_buf_queue(struct v4l2_m2m_ctx *m2m_ctx,
 static inline
 unsigned int v4l2_m2m_num_src_bufs_ready(struct v4l2_m2m_ctx *m2m_ctx)
 {
-       return m2m_ctx->out_q_ctx.num_rdy;
+       unsigned int num_buf_rdy;
+       unsigned long flags;
+
+       spin_lock_irqsave(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);
+       num_buf_rdy = m2m_ctx->out_q_ctx.num_rdy;
+       spin_unlock_irqrestore(&m2m_ctx->out_q_ctx.rdy_spinlock, flags);
+
+       return num_buf_rdy;
 }
 
 /**
@@ -605,7 +612,14 @@ unsigned int v4l2_m2m_num_src_bufs_ready(struct v4l2_m2m_ctx *m2m_ctx)
 static inline
 unsigned int v4l2_m2m_num_dst_bufs_ready(struct v4l2_m2m_ctx *m2m_ctx)
 {
-       return m2m_ctx->cap_q_ctx.num_rdy;
+       unsigned int num_buf_rdy;
+       unsigned long flags;
+
+       spin_lock_irqsave(&m2m_ctx->cap_q_ctx.rdy_spinlock, flags);
+       num_buf_rdy = m2m_ctx->cap_q_ctx.num_rdy;
+       spin_unlock_irqrestore(&m2m_ctx->cap_q_ctx.rdy_spinlock, flags);
+
+       return num_buf_rdy;
 }
 
 /**