[media] vb2: Push mmap_sem down to memops

Currently vb2 core acquires mmap_sem just around call to
__qbuf_userptr(). However since commit f035eb4e976ef5 (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: Jan Kara <jack@suse.cz>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/media/v4l2-core/videobuf2-vmalloc.c b/drivers/media/v4l2-core/videobuf2-vmalloc.c
index 657ab302a5cf..0ba40be21ebd 100644
--- a/drivers/media/v4l2-core/videobuf2-vmalloc.c
+++ b/drivers/media/v4l2-core/videobuf2-vmalloc.c
@@ -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 @@ fail_get_user_pages:
 	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);
 }