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V4L/DVB: videobuf: prepare to make locking optional in videobuf
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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>
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Hans Verkuil authored and Mauro Carvalho Chehab committed Oct 21, 2010
1 parent ee6869a commit 9739768
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Showing 6 changed files with 55 additions and 42 deletions.
8 changes: 4 additions & 4 deletions drivers/media/video/v4l2-mem2mem.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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);
Expand Down
64 changes: 32 additions & 32 deletions drivers/media/video/videobuf-core.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand All @@ -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;
Expand Down Expand Up @@ -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);
Expand All @@ -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;
Expand All @@ -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);
Expand All @@ -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");
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -635,14 +635,14 @@ static int stream_next_buffer_check_queue(struct videobuf_queue *q, int noblock)
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;
Expand Down Expand Up @@ -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) {
Expand All @@ -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);
Expand All @@ -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;
Expand All @@ -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);
Expand All @@ -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;
}
Expand Down Expand Up @@ -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);

Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -999,33 +999,33 @@ 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;
}
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);

if (q->reading)
__videobuf_read_stop(q);

mutex_unlock(&q->vb_lock);
videobuf_queue_unlock(q);
}
EXPORT_SYMBOL_GPL(videobuf_stop);

Expand All @@ -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;
Expand Down Expand Up @@ -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);
Expand All @@ -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,
Expand Down Expand Up @@ -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);
Expand All @@ -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];

Expand All @@ -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;
}
Expand Down
4 changes: 2 additions & 2 deletions drivers/media/video/videobuf-dma-contig.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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);
}
}

Expand Down
4 changes: 2 additions & 2 deletions drivers/media/video/videobuf-dma-sg.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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;
Expand Down
4 changes: 2 additions & 2 deletions drivers/media/video/videobuf-vmalloc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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;
Expand Down
13 changes: 13 additions & 0 deletions include/media/videobuf-core.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand Down Expand Up @@ -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);
Expand Down

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