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: 76219d88204b ("drm/qxl: unpin release objects")
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20210217123213.2199186-5-kraxel@redhat.com
(cherry picked from commit 19089b760e56c97458c272e90e43da761b05cf12)
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

diff --git a/drivers/gpu/drm/qxl/qxl_release.c b/drivers/gpu/drm/qxl/qxl_release.c
index 93b5f7ab055dee92beb1d67e4fff8bb9b9243ac2..b372455e272986fe09374d66d0fb9be96928cda6 100644 (file)
--- a/drivers/gpu/drm/qxl/qxl_release.c
+++ b/drivers/gpu/drm/qxl/qxl_release.c
@@ -321,7 +321,7 @@ 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;
@@ -347,8 +347,7 @@ 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;
        }
@@ -356,6 +355,10 @@ int qxl_alloc_release_reserved(struct qxl_device *qdev, unsigned long size,
                ret = qxl_release_bo_alloc(qdev, &qdev->current_release_bo[cur_idx]);
                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;
                }
@@ -371,6 +374,10 @@ 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);