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media: videobuf2-core: take mmap_lock in vb2_get_unmapped_area()
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While vb2_mmap took the mmap_lock mutex, vb2_get_unmapped_area didn't.
Add this.

Also take this opportunity to move the 'q->memory != VB2_MEMORY_MMAP'
check and vb2_fileio_is_active() check into __find_plane_by_offset() so
both vb2_mmap and vb2_get_unmapped_area do the same checks.

Since q->memory is checked while mmap_lock is held, also take that lock
in reqbufs and create_bufs when it is set, and set it back to
MEMORY_UNKNOWN on error.

Fixes: f035eb4 ("[media] videobuf2: fix lockdep warning")
Signed-off-by: Hans Verkuil <[email protected]>
Acked-by: Tomasz Figa <[email protected]>
Reviewed-by: Ricardo Ribalda <[email protected]>
Signed-off-by: Mauro Carvalho Chehab <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@torvalds
Hans Verkuil authored and torvalds committed Dec 7, 2022
1 parent 8ed710d commit 098e5ed
Showing 1 changed file with 73 additions and 29 deletions.
102 changes: 73 additions & 29 deletions drivers/media/common/videobuf2/videobuf2-core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -813,7 +813,13 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
num_buffers = max_t(unsigned int, *count, q->min_buffers_needed);
num_buffers = min_t(unsigned int, num_buffers, VB2_MAX_FRAME);
memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
/*
* Set this now to ensure that drivers see the correct q->memory value
* in the queue_setup op.
*/
mutex_lock(&q->mmap_lock);
q->memory = memory;
mutex_unlock(&q->mmap_lock);
set_queue_coherency(q, non_coherent_mem);

/*
Expand All @@ -823,22 +829,27 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
ret = call_qop(q, queue_setup, q, &num_buffers, &num_planes,
plane_sizes, q->alloc_devs);
if (ret)
return ret;
goto error;

/* Check that driver has set sane values */
if (WARN_ON(!num_planes))
return -EINVAL;
if (WARN_ON(!num_planes)) {
ret = -EINVAL;
goto error;
}

for (i = 0; i < num_planes; i++)
if (WARN_ON(!plane_sizes[i]))
return -EINVAL;
if (WARN_ON(!plane_sizes[i])) {
ret = -EINVAL;
goto error;
}

/* Finally, allocate buffers and video memory */
allocated_buffers =
__vb2_queue_alloc(q, memory, num_buffers, num_planes, plane_sizes);
if (allocated_buffers == 0) {
dprintk(q, 1, "memory allocation failed\n");
return -ENOMEM;
ret = -ENOMEM;
goto error;
}

/*
Expand Down Expand Up @@ -879,7 +890,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
if (ret < 0) {
/*
* Note: __vb2_queue_free() will subtract 'allocated_buffers'
* from q->num_buffers.
* from q->num_buffers and it will reset q->memory to
* VB2_MEMORY_UNKNOWN.
*/
__vb2_queue_free(q, allocated_buffers);
mutex_unlock(&q->mmap_lock);
Expand All @@ -895,6 +907,12 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
q->waiting_for_buffers = !q->is_output;

return 0;

error:
mutex_lock(&q->mmap_lock);
q->memory = VB2_MEMORY_UNKNOWN;
mutex_unlock(&q->mmap_lock);
return ret;
}
EXPORT_SYMBOL_GPL(vb2_core_reqbufs);

Expand All @@ -906,20 +924,27 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
unsigned int num_planes = 0, num_buffers, allocated_buffers;
unsigned plane_sizes[VB2_MAX_PLANES] = { };
bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
bool no_previous_buffers = !q->num_buffers;
int ret;

if (q->num_buffers == VB2_MAX_FRAME) {
dprintk(q, 1, "maximum number of buffers already allocated\n");
return -ENOBUFS;
}

if (!q->num_buffers) {
if (no_previous_buffers) {
if (q->waiting_in_dqbuf && *count) {
dprintk(q, 1, "another dup()ped fd is waiting for a buffer\n");
return -EBUSY;
}
memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
/*
* Set this now to ensure that drivers see the correct q->memory
* value in the queue_setup op.
*/
mutex_lock(&q->mmap_lock);
q->memory = memory;
mutex_unlock(&q->mmap_lock);
q->waiting_for_buffers = !q->is_output;
set_queue_coherency(q, non_coherent_mem);
} else {
Expand All @@ -945,14 +970,15 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
ret = call_qop(q, queue_setup, q, &num_buffers,
&num_planes, plane_sizes, q->alloc_devs);
if (ret)
return ret;
goto error;

/* Finally, allocate buffers and video memory */
allocated_buffers = __vb2_queue_alloc(q, memory, num_buffers,
num_planes, plane_sizes);
if (allocated_buffers == 0) {
dprintk(q, 1, "memory allocation failed\n");
return -ENOMEM;
ret = -ENOMEM;
goto error;
}

/*
Expand Down Expand Up @@ -983,7 +1009,8 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
if (ret < 0) {
/*
* Note: __vb2_queue_free() will subtract 'allocated_buffers'
* from q->num_buffers.
* from q->num_buffers and it will reset q->memory to
* VB2_MEMORY_UNKNOWN.
*/
__vb2_queue_free(q, allocated_buffers);
mutex_unlock(&q->mmap_lock);
Expand All @@ -998,6 +1025,14 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
*count = allocated_buffers;

return 0;

error:
if (no_previous_buffers) {
mutex_lock(&q->mmap_lock);
q->memory = VB2_MEMORY_UNKNOWN;
mutex_unlock(&q->mmap_lock);
}
return ret;
}
EXPORT_SYMBOL_GPL(vb2_core_create_bufs);

Expand Down Expand Up @@ -2164,6 +2199,22 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long off,
struct vb2_buffer *vb;
unsigned int buffer, plane;

/*
* Sanity checks to ensure the lock is held, MEMORY_MMAP is
* used and fileio isn't active.
*/
lockdep_assert_held(&q->mmap_lock);

if (q->memory != VB2_MEMORY_MMAP) {
dprintk(q, 1, "queue is not currently set up for mmap\n");
return -EINVAL;
}

if (vb2_fileio_is_active(q)) {
dprintk(q, 1, "file io in progress\n");
return -EBUSY;
}

/*
* Go over all buffers and their planes, comparing the given offset
* with an offset assigned to each plane. If a match is found,
Expand Down Expand Up @@ -2265,11 +2316,6 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
int ret;
unsigned long length;

if (q->memory != VB2_MEMORY_MMAP) {
dprintk(q, 1, "queue is not currently set up for mmap\n");
return -EINVAL;
}

/*
* Check memory area access mode.
*/
Expand All @@ -2291,14 +2337,9 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)

mutex_lock(&q->mmap_lock);

if (vb2_fileio_is_active(q)) {
dprintk(q, 1, "mmap: file io in progress\n");
ret = -EBUSY;
goto unlock;
}

/*
* Find the plane corresponding to the offset passed by userspace.
* Find the plane corresponding to the offset passed by userspace. This
* will return an error if not MEMORY_MMAP or file I/O is in progress.
*/
ret = __find_plane_by_offset(q, off, &buffer, &plane);
if (ret)
Expand Down Expand Up @@ -2351,22 +2392,25 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
void *vaddr;
int ret;

if (q->memory != VB2_MEMORY_MMAP) {
dprintk(q, 1, "queue is not currently set up for mmap\n");
return -EINVAL;
}
mutex_lock(&q->mmap_lock);

/*
* Find the plane corresponding to the offset passed by userspace.
* Find the plane corresponding to the offset passed by userspace. This
* will return an error if not MEMORY_MMAP or file I/O is in progress.
*/
ret = __find_plane_by_offset(q, off, &buffer, &plane);
if (ret)
return ret;
goto unlock;

vb = q->bufs[buffer];

vaddr = vb2_plane_vaddr(vb, plane);
mutex_unlock(&q->mmap_lock);
return vaddr ? (unsigned long)vaddr : -EINVAL;

unlock:
mutex_unlock(&q->mmap_lock);
return ret;
}
EXPORT_SYMBOL_GPL(vb2_get_unmapped_area);
#endif
Expand Down

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