Gerd Hoffmann
2021-Feb-17 12:32 UTC
[PATCH v2 04/11] 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 716d706ca7f0..f5845c96d414 100644
--- a/drivers/gpu/drm/qxl/qxl_release.c
+++ b/drivers/gpu/drm/qxl/qxl_release.c
@@ -283,7 +283,7 @@ 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;
@@ -315,8 +315,7 @@ 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;
}
@@ -324,6 +323,10 @@ 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;
}
@@ -339,6 +342,10 @@ 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
Thomas Zimmermann
2021-Feb-17 19:23 UTC
[PATCH v2 04/11] drm/qxl: fix lockdep issue in qxl_alloc_release_reserved
Am 17.02.21 um 13:32 schrieb Gerd Hoffmann:> 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>Acked-by: Thomas Zimmermann <tzimmermann at suse.de>> --- > 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 716d706ca7f0..f5845c96d414 100644 > --- a/drivers/gpu/drm/qxl/qxl_release.c > +++ b/drivers/gpu/drm/qxl/qxl_release.c > @@ -283,7 +283,7 @@ 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; > @@ -315,8 +315,7 @@ 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; > } > @@ -324,6 +323,10 @@ 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; > } > @@ -339,6 +342,10 @@ 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); >-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 N?rnberg, Germany (HRB 36809, AG N?rnberg) Gesch?ftsf?hrer: Felix Imend?rffer -------------- next part -------------- A non-text attachment was scrubbed... Name: OpenPGP_signature Type: application/pgp-signature Size: 840 bytes Desc: OpenPGP digital signature URL: <http://lists.linuxfoundation.org/pipermail/virtualization/attachments/20210217/b70a09d4/attachment-0001.sig>