Gerd Hoffmann
2021-Feb-16 11:37 UTC
[PATCH 04/10] drm/qxl: fix lockdep issue in qxl_alloc_release_reserved
Call qxl_bo_unpin (which does a reservation) without holding the
release_mutex lock. Fixes lockdep (correctly) warning on a possible
deadlock.
Fixes: 65ffea3c6e73 ("drm/qxl: unpin release objects")
Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
---
drivers/gpu/drm/qxl/qxl_release.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/qxl/qxl_release.c
b/drivers/gpu/drm/qxl/qxl_release.c
index a831184e014a..352a11a8485b 100644
--- a/drivers/gpu/drm/qxl/qxl_release.c
+++ b/drivers/gpu/drm/qxl/qxl_release.c
@@ -284,7 +284,7 @@ int qxl_alloc_release_reserved(struct qxl_device *qdev,
unsigned long size,
int type, struct qxl_release **release,
struct qxl_bo **rbo)
{
- struct qxl_bo *bo;
+ struct qxl_bo *bo, *free_bo = NULL;
int idr_ret;
int ret = 0;
union qxl_release_info *info;
@@ -317,8 +317,7 @@ int qxl_alloc_release_reserved(struct qxl_device *qdev,
unsigned long size,
mutex_lock(&qdev->release_mutex);
if (qdev->current_release_bo_offset[cur_idx] + 1 >=
releases_per_bo[cur_idx]) {
- qxl_bo_unpin(qdev->current_release_bo[cur_idx]);
- qxl_bo_unref(&qdev->current_release_bo[cur_idx]);
+ free_bo = qdev->current_release_bo[cur_idx];
qdev->current_release_bo_offset[cur_idx] = 0;
qdev->current_release_bo[cur_idx] = NULL;
}
@@ -326,6 +325,10 @@ int qxl_alloc_release_reserved(struct qxl_device *qdev,
unsigned long size,
ret = qxl_release_bo_alloc(qdev, &qdev->current_release_bo[cur_idx],
priority);
if (ret) {
mutex_unlock(&qdev->release_mutex);
+ if (free_bo) {
+ qxl_bo_unpin(free_bo);
+ qxl_bo_unref(&free_bo);
+ }
qxl_release_free(qdev, *release);
return ret;
}
@@ -341,6 +344,10 @@ int qxl_alloc_release_reserved(struct qxl_device *qdev,
unsigned long size,
*rbo = bo;
mutex_unlock(&qdev->release_mutex);
+ if (free_bo) {
+ qxl_bo_unpin(free_bo);
+ qxl_bo_unref(&free_bo);
+ }
ret = qxl_release_list_add(*release, bo);
qxl_bo_unref(&bo);
--
2.29.2