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Commit 48b25a3a authored by Jan Kara's avatar Jan Kara Committed by Mauro Carvalho Chehab
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[media] vb2: Push mmap_sem down to memops 



Currently vb2 core acquires mmap_sem just around call to
__qbuf_userptr(). However since commit f035eb4e (videobuf2: fix
lockdep warning) it isn't necessary to acquire it so early as we no
longer have to drop queue mutex before acquiring mmap_sem. So push
acquisition of mmap_sem down into .get_userptr and .put_userptr memops
so that the semaphore is acquired for a shorter time and it is clearer
what it is needed for.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
parent 9c3f2052

drivers/media/v4l2-core/videobuf2-core.c

+0 −2
Original line number Diff line number Diff line
@@ -1657,9 +1657,7 @@ static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b) 
		ret = __qbuf_mmap(vb, b);

		break;

	case V4L2_MEMORY_USERPTR:

		down_read(&current->mm->mmap_sem);

		ret = __qbuf_userptr(vb, b);

		up_read(&current->mm->mmap_sem);

		break;

	case V4L2_MEMORY_DMABUF:

		ret = __qbuf_dmabuf(vb, b);

drivers/media/v4l2-core/videobuf2-dma-contig.c

+7 −0
Original line number Diff line number Diff line
@@ -532,7 +532,9 @@ static void vb2_dc_put_userptr(void *buf_priv) 
		sg_free_table(sgt);

		kfree(sgt);

	}

	down_read(&current->mm->mmap_sem);

	vb2_put_vma(buf->vma);

	up_read(&current->mm->mmap_sem);

	kfree(buf);

}
@@ -616,6 +618,7 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr, 
		goto fail_buf;

	}



	down_read(&current->mm->mmap_sem);

	/* current->mm->mmap_sem is taken by videobuf2 core */

	vma = find_vma(current->mm, vaddr);

	if (!vma) {
@@ -642,6 +645,7 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr, 
	if (ret) {

		unsigned long pfn;

		if (vb2_dc_get_user_pfn(start, n_pages, vma, &pfn) == 0) {

			up_read(&current->mm->mmap_sem);

			buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, pfn);

			buf->size = size;

			kfree(pages);
@@ -651,6 +655,7 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr, 
		pr_err("failed to get user pages\n");

		goto fail_vma;

	}

	up_read(&current->mm->mmap_sem);



	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);

	if (!sgt) {
@@ -713,10 +718,12 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr, 
		while (n_pages)

			put_page(pages[--n_pages]);



	down_read(&current->mm->mmap_sem);

fail_vma:

	vb2_put_vma(buf->vma);



fail_pages:

	up_read(&current->mm->mmap_sem);

	kfree(pages); /* kfree is NULL-proof */



fail_buf:

drivers/media/v4l2-core/videobuf2-dma-sg.c

+6 −0
Original line number Diff line number Diff line
@@ -263,6 +263,7 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr, 
	if (!buf->pages)

		goto userptr_fail_alloc_pages;



	down_read(&current->mm->mmap_sem);

	vma = find_vma(current->mm, vaddr);

	if (!vma) {

		dprintk(1, "no vma for address %lu\n", vaddr);
@@ -301,6 +302,7 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr, 
					     1, /* force */

					     buf->pages,

					     NULL);

	up_read(&current->mm->mmap_sem);



	if (num_pages_from_user != buf->num_pages)

		goto userptr_fail_get_user_pages;
@@ -328,8 +330,10 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr, 
	if (!vma_is_io(buf->vma))

		while (--num_pages_from_user >= 0)

			put_page(buf->pages[num_pages_from_user]);

	down_read(&current->mm->mmap_sem);

	vb2_put_vma(buf->vma);

userptr_fail_find_vma:

	up_read(&current->mm->mmap_sem);

	kfree(buf->pages);

userptr_fail_alloc_pages:

	kfree(buf);
@@ -362,7 +366,9 @@ static void vb2_dma_sg_put_userptr(void *buf_priv) 
			put_page(buf->pages[i]);

	}

	kfree(buf->pages);

	down_read(&current->mm->mmap_sem);

	vb2_put_vma(buf->vma);

	up_read(&current->mm->mmap_sem);

	kfree(buf);

}

drivers/media/v4l2-core/videobuf2-vmalloc.c

+5 −1
Original line number Diff line number Diff line
@@ -89,7 +89,7 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx, unsigned long vaddr, 
	offset = vaddr & ~PAGE_MASK;

	buf->size = size;





	down_read(&current->mm->mmap_sem);

	vma = find_vma(current->mm, vaddr);

	if (vma && (vma->vm_flags & VM_PFNMAP) && (vma->vm_pgoff)) {

		if (vb2_get_contig_userptr(vaddr, size, &vma, &physp))
@@ -121,6 +121,7 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx, unsigned long vaddr, 
		if (!buf->vaddr)

			goto fail_get_user_pages;

	}

	up_read(&current->mm->mmap_sem);



	buf->vaddr += offset;

	return buf;
@@ -133,6 +134,7 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx, unsigned long vaddr, 
	kfree(buf->pages);



fail_pages_array_alloc:

	up_read(&current->mm->mmap_sem);

	kfree(buf);



	return NULL;
@@ -144,6 +146,7 @@ static void vb2_vmalloc_put_userptr(void *buf_priv) 
	unsigned long vaddr = (unsigned long)buf->vaddr & PAGE_MASK;

	unsigned int i;



	down_read(&current->mm->mmap_sem);

	if (buf->pages) {

		if (vaddr)

			vm_unmap_ram((void *)vaddr, buf->n_pages);
@@ -157,6 +160,7 @@ static void vb2_vmalloc_put_userptr(void *buf_priv) 
		vb2_put_vma(buf->vma);

		iounmap((__force void __iomem *)buf->vaddr);

	}

	up_read(&current->mm->mmap_sem);

	kfree(buf);

}