V4L/DVB: videobuf: prepare to make locking optional in videobuf

Currently videobuf uses the vb_lock mutex to lock its data structures.
But this locking will (optionally) move into the v4l2 core, which means
that in that case vb_lock shouldn't be used since the external lock is already
held.

Prepare for this by adding a pointer to such an external mutex and
don't lock if that pointer is set.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

6 files changed, 55 insertions, 42 deletions

diff --git a/drivers/media/video/v4l2-mem2mem.c b/drivers/media/video/v4l2-mem2mem.c
index f45f9405ea39..ac832a28e18e 100644
--- a/drivers/media/video/v4l2-mem2mem.c
+++ b/drivers/media/video/v4l2-mem2mem.c
@@ -421,8 +421,8 @@ unsigned int v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
         src_q = v4l2_m2m_get_src_vq(m2m_ctx);
         dst_q = v4l2_m2m_get_dst_vq(m2m_ctx);
 
-        mutex_lock(&src_q->vb_lock);
-        mutex_lock(&dst_q->vb_lock);
+        videobuf_queue_lock(src_q);
+        videobuf_queue_lock(dst_q);
 
         if (src_q->streaming && !list_empty(&src_q->stream))
                 src_vb = list_first_entry(&src_q->stream,
@@ -450,8 +450,8 @@ unsigned int v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
         }
 
 end:
-        mutex_unlock(&dst_q->vb_lock);
-        mutex_unlock(&src_q->vb_lock);
+        videobuf_queue_unlock(dst_q);
+        videobuf_queue_unlock(src_q);
         return rc;
 }
 EXPORT_SYMBOL_GPL(v4l2_m2m_poll);
diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c
index ce1595bef629..2930665910b7 100644
--- a/drivers/media/video/videobuf-core.c
+++ b/drivers/media/video/videobuf-core.c
@@ -350,9 +350,9 @@ static void videobuf_status(struct videobuf_queue *q, struct v4l2_buffer *b,
 int videobuf_mmap_free(struct videobuf_queue *q)
 {
         int ret;
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         ret = __videobuf_free(q);
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
         return ret;
 }
 EXPORT_SYMBOL_GPL(videobuf_mmap_free);
@@ -407,9 +407,9 @@ int videobuf_mmap_setup(struct videobuf_queue *q,
                         enum v4l2_memory memory)
 {
         int ret;
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         ret = __videobuf_mmap_setup(q, bcount, bsize, memory);
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
         return ret;
 }
 EXPORT_SYMBOL_GPL(videobuf_mmap_setup);
@@ -432,7 +432,7 @@ int videobuf_reqbufs(struct videobuf_queue *q,
                 return -EINVAL;
         }
 
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         if (req->type != q->type) {
                 dprintk(1, "reqbufs: queue type invalid\n");
                 retval = -EINVAL;
@@ -469,7 +469,7 @@ int videobuf_reqbufs(struct videobuf_queue *q,
         retval = 0;
 
  done:
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
         return retval;
 }
 EXPORT_SYMBOL_GPL(videobuf_reqbufs);
@@ -478,7 +478,7 @@ int videobuf_querybuf(struct videobuf_queue *q, struct v4l2_buffer *b)
 {
         int ret = -EINVAL;
 
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         if (unlikely(b->type != q->type)) {
                 dprintk(1, "querybuf: Wrong type.\n");
                 goto done;
@@ -496,7 +496,7 @@ int videobuf_querybuf(struct videobuf_queue *q, struct v4l2_buffer *b)
 
         ret = 0;
 done:
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
         return ret;
 }
 EXPORT_SYMBOL_GPL(videobuf_querybuf);
@@ -513,7 +513,7 @@ int videobuf_qbuf(struct videobuf_queue *q, struct v4l2_buffer *b)
         if (b->memory == V4L2_MEMORY_MMAP)
                 down_read(&current->mm->mmap_sem);
 
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         retval = -EBUSY;
         if (q->reading) {
                 dprintk(1, "qbuf: Reading running...\n");
@@ -605,7 +605,7 @@ int videobuf_qbuf(struct videobuf_queue *q, struct v4l2_buffer *b)
         wake_up_interruptible_sync(&q->wait);
 
 done:
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
 
         if (b->memory == V4L2_MEMORY_MMAP)
                 up_read(&current->mm->mmap_sem);
@@ -635,14 +635,14 @@ checks:
                         dprintk(2, "next_buffer: waiting on buffer\n");
 
                         /* Drop lock to avoid deadlock with qbuf */
-                        mutex_unlock(&q->vb_lock);
+                        videobuf_queue_unlock(q);
 
                         /* Checking list_empty and streaming is safe without
                          * locks because we goto checks to validate while
                          * holding locks before proceeding */
                         retval = wait_event_interruptible(q->wait,
                                 !list_empty(&q->stream) || !q->streaming);
-                        mutex_lock(&q->vb_lock);
+                        videobuf_queue_lock(q);
 
                         if (retval)
                                 goto done;
@@ -687,7 +687,7 @@ int videobuf_dqbuf(struct videobuf_queue *q,
         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 
         memset(b, 0, sizeof(*b));
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
 
         retval = stream_next_buffer(q, &buf, nonblocking);
         if (retval < 0) {
@@ -713,7 +713,7 @@ int videobuf_dqbuf(struct videobuf_queue *q,
         buf->state = VIDEOBUF_IDLE;
         b->flags &= ~V4L2_BUF_FLAG_DONE;
 done:
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
         return retval;
 }
 EXPORT_SYMBOL_GPL(videobuf_dqbuf);
@@ -724,7 +724,7 @@ int videobuf_streamon(struct videobuf_queue *q)
         unsigned long flags = 0;
         int retval;
 
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         retval = -EBUSY;
         if (q->reading)
                 goto done;
@@ -740,7 +740,7 @@ int videobuf_streamon(struct videobuf_queue *q)
 
         wake_up_interruptible_sync(&q->wait);
 done:
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
         return retval;
 }
 EXPORT_SYMBOL_GPL(videobuf_streamon);
@@ -760,9 +760,9 @@ int videobuf_streamoff(struct videobuf_queue *q)
 {
         int retval;
 
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         retval = __videobuf_streamoff(q);
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
 
         return retval;
 }
@@ -868,7 +868,7 @@ ssize_t videobuf_read_one(struct videobuf_queue *q,
 
         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
 
         q->ops->buf_setup(q, &nbufs, &size);
 
@@ -938,7 +938,7 @@ ssize_t videobuf_read_one(struct videobuf_queue *q,
         }
 
 done:
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
         return retval;
 }
 EXPORT_SYMBOL_GPL(videobuf_read_one);
@@ -999,9 +999,9 @@ int videobuf_read_start(struct videobuf_queue *q)
 {
         int rc;
 
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         rc = __videobuf_read_start(q);
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
 
         return rc;
 }
@@ -1009,15 +1009,15 @@ EXPORT_SYMBOL_GPL(videobuf_read_start);
 
 void videobuf_read_stop(struct videobuf_queue *q)
 {
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         __videobuf_read_stop(q);
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
 }
 EXPORT_SYMBOL_GPL(videobuf_read_stop);
 
 void videobuf_stop(struct videobuf_queue *q)
 {
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
 
         if (q->streaming)
                 __videobuf_streamoff(q);
@@ -1025,7 +1025,7 @@ void videobuf_stop(struct videobuf_queue *q)
         if (q->reading)
                 __videobuf_read_stop(q);
 
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
 }
 EXPORT_SYMBOL_GPL(videobuf_stop);
 
@@ -1039,7 +1039,7 @@ ssize_t videobuf_read_stream(struct videobuf_queue *q,
         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 
         dprintk(2, "%s\n", __func__);
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         retval = -EBUSY;
         if (q->streaming)
                 goto done;
@@ -1097,7 +1097,7 @@ ssize_t videobuf_read_stream(struct videobuf_queue *q,
         }
 
 done:
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
         return retval;
 }
 EXPORT_SYMBOL_GPL(videobuf_read_stream);
@@ -1109,7 +1109,7 @@ unsigned int videobuf_poll_stream(struct file *file,
         struct videobuf_buffer *buf = NULL;
         unsigned int rc = 0;
 
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         if (q->streaming) {
                 if (!list_empty(&q->stream))
                         buf = list_entry(q->stream.next,
@@ -1147,7 +1147,7 @@ unsigned int videobuf_poll_stream(struct file *file,
                         }
                 }
         }
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
         return rc;
 }
 EXPORT_SYMBOL_GPL(videobuf_poll_stream);
@@ -1164,7 +1164,7 @@ int videobuf_mmap_mapper(struct videobuf_queue *q, struct vm_area_struct *vma)
                 return -EINVAL;
         }
 
-        mutex_lock(&q->vb_lock);
+        videobuf_queue_lock(q);
         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
                 struct videobuf_buffer *buf = q->bufs[i];
 
@@ -1174,7 +1174,7 @@ int videobuf_mmap_mapper(struct videobuf_queue *q, struct vm_area_struct *vma)
                         break;
                 }
         }
-        mutex_unlock(&q->vb_lock);
+        videobuf_queue_unlock(q);
 
         return rc;
 }
diff --git a/drivers/media/video/videobuf-dma-contig.c b/drivers/media/video/videobuf-dma-contig.c
index 6ff9e4bac3ea..047054f79601 100644
--- a/drivers/media/video/videobuf-dma-contig.c
+++ b/drivers/media/video/videobuf-dma-contig.c
@@ -63,7 +63,7 @@ static void videobuf_vm_close(struct vm_area_struct *vma)
                 struct videobuf_dma_contig_memory *mem;
 
                 dev_dbg(q->dev, "munmap %p q=%p\n", map, q);
-                mutex_lock(&q->vb_lock);
+                videobuf_queue_lock(q);
 
                 /* We need first to cancel streams, before unmapping */
                 if (q->streaming)
@@ -103,7 +103,7 @@ static void videobuf_vm_close(struct vm_area_struct *vma)
 
                 kfree(map);
 
-                mutex_unlock(&q->vb_lock);
+                videobuf_queue_unlock(q);
         }
 }
 
diff --git a/drivers/media/video/videobuf-dma-sg.c b/drivers/media/video/videobuf-dma-sg.c
index 2ad0bc252b0e..515ae887ffcf 100644
--- a/drivers/media/video/videobuf-dma-sg.c
+++ b/drivers/media/video/videobuf-dma-sg.c
@@ -358,7 +358,7 @@ static void videobuf_vm_close(struct vm_area_struct *vma)
         map->count--;
         if (0 == map->count) {
                 dprintk(1, "munmap %p q=%p\n", map, q);
-                mutex_lock(&q->vb_lock);
+                videobuf_queue_lock(q);
                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
                         if (NULL == q->bufs[i])
                                 continue;
@@ -374,7 +374,7 @@ static void videobuf_vm_close(struct vm_area_struct *vma)
                         q->bufs[i]->baddr = 0;
                         q->ops->buf_release(q, q->bufs[i]);
                 }
-                mutex_unlock(&q->vb_lock);
+                videobuf_queue_unlock(q);
                 kfree(map);
         }
         return;
diff --git a/drivers/media/video/videobuf-vmalloc.c b/drivers/media/video/videobuf-vmalloc.c
index e7fe31d54f07..91348b3170ff 100644
--- a/drivers/media/video/videobuf-vmalloc.c
+++ b/drivers/media/video/videobuf-vmalloc.c
@@ -75,7 +75,7 @@ static void videobuf_vm_close(struct vm_area_struct *vma)
                 struct videobuf_vmalloc_memory *mem;
 
                 dprintk(1, "munmap %p q=%p\n", map, q);
-                mutex_lock(&q->vb_lock);
+                videobuf_queue_lock(q);
 
                 /* We need first to cancel streams, before unmapping */
                 if (q->streaming)
@@ -114,7 +114,7 @@ static void videobuf_vm_close(struct vm_area_struct *vma)
 
                 kfree(map);
 
-                mutex_unlock(&q->vb_lock);
+                videobuf_queue_unlock(q);
         }
 
         return;
diff --git a/include/media/videobuf-core.h b/include/media/videobuf-core.h
index f2c41cebf453..f5eb2cbf3002 100644
--- a/include/media/videobuf-core.h
+++ b/include/media/videobuf-core.h
@@ -139,6 +139,7 @@ struct videobuf_qtype_ops {
 
 struct videobuf_queue {
         struct mutex               vb_lock;
+        struct mutex               *ext_lock;
         spinlock_t                 *irqlock;
         struct device              *dev;
 
@@ -167,6 +168,18 @@ struct videobuf_queue {
         void                       *priv_data;
 };
 
+static inline void videobuf_queue_lock(struct videobuf_queue *q)
+{
+        if (!q->ext_lock)
+                mutex_lock(&q->vb_lock);
+}
+
+static inline void videobuf_queue_unlock(struct videobuf_queue *q)
+{
+        if (!q->ext_lock)
+                mutex_unlock(&q->vb_lock);
+}
+
 int videobuf_waiton(struct videobuf_buffer *vb, int non_blocking, int intr);
 int videobuf_iolock(struct videobuf_queue *q, struct videobuf_buffer *vb,
                 struct v4l2_framebuffer *fbuf);