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77 lines
2.9 KiB
Diff
77 lines
2.9 KiB
Diff
From a79fa33b2d58a7c0f60a0ef31691625990894858 Mon Sep 17 00:00:00 2001
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From: John Sheu <sheu@chromium.org>
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Date: Thu, 15 Oct 2015 18:05:25 +0900
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Subject: [PATCH 282/782] media: vb2: Allow reqbufs(0) with "in use" MMAP
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buffers
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Videobuf2 presently does not allow VIDIOC_REQBUFS to destroy outstanding
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buffers if the queue is of type V4L2_MEMORY_MMAP, and if the buffers are
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considered "in use". This is different behavior than for other memory
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types and prevents us from deallocating buffers in following two cases:
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1) There are outstanding mmap()ed views on the buffer. However even if
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we put the buffer in reqbufs(0), there will be remaining references,
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due to vma .open/close() adjusting vb2 buffer refcount appropriately.
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This means that the buffer will be in fact freed only when the last
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mmap()ed view is unmapped.
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2) Buffer has been exported as a DMABUF. Refcount of the vb2 buffer
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is managed properly by VB2 DMABUF ops, i.e. incremented on DMABUF
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get and decremented on DMABUF release. This means that the buffer
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will be alive until all importers release it.
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Considering both cases above, there does not seem to be any need to
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prevent reqbufs(0) operation, because buffer lifetime is already
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properly managed by both mmap() and DMABUF code paths. Let's remove it
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and allow userspace freeing the queue (and potentially allocating a new
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one) even though old buffers might be still in processing.
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Signed-off-by: John Sheu <sheu@chromium.org>
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Reviewed-by: Pawel Osciak <posciak@chromium.org>
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Reviewed-by: Tomasz Figa <tfiga@chromium.org>
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Signed-off-by: Tomasz Figa <tfiga@chromium.org>
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---
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.../media/common/videobuf2/videobuf2-core.c | 23 -------------------
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1 file changed, 23 deletions(-)
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--- a/drivers/media/common/videobuf2/videobuf2-core.c
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+++ b/drivers/media/common/videobuf2/videobuf2-core.c
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@@ -554,20 +554,6 @@ bool vb2_buffer_in_use(struct vb2_queue
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}
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EXPORT_SYMBOL(vb2_buffer_in_use);
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-/*
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- * __buffers_in_use() - return true if any buffers on the queue are in use and
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- * the queue cannot be freed (by the means of REQBUFS(0)) call
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- */
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-static bool __buffers_in_use(struct vb2_queue *q)
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-{
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- unsigned int buffer;
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- for (buffer = 0; buffer < q->num_buffers; ++buffer) {
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- if (vb2_buffer_in_use(q, q->bufs[buffer]))
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- return true;
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- }
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- return false;
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-}
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-
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void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb)
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{
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call_void_bufop(q, fill_user_buffer, q->bufs[index], pb);
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@@ -679,16 +665,7 @@ int vb2_core_reqbufs(struct vb2_queue *q
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if (*count == 0 || q->num_buffers != 0 ||
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(q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory)) {
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- /*
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- * We already have buffers allocated, so first check if they
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- * are not in use and can be freed.
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- */
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mutex_lock(&q->mmap_lock);
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- if (q->memory == VB2_MEMORY_MMAP && __buffers_in_use(q)) {
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- mutex_unlock(&q->mmap_lock);
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- dprintk(1, "memory in use, cannot free\n");
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- return -EBUSY;
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- }
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/*
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* Call queue_cancel to clean up any buffers in the PREPARED or
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