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From: Gerd Hoffmann <kraxel@redhat.com>
To: dri-devel@lists.freedesktop.org
Cc: Gerd Hoffmann <kraxel@redhat.com>,
	Dave Airlie <airlied@redhat.com>, David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel@ffwll.ch>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	virtualization@lists.linux-foundation.org (open list:DRM DRIVER
	FOR QXL VIRTUAL GPU),
	spice-devel@lists.freedesktop.org (open list:DRM DRIVER FOR QXL
	VIRTUAL GPU), linux-kernel@vger.kernel.org (open list)
Subject: [PATCH 04/10] drm/qxl: fix lockdep issue in qxl_alloc_release_reserved
Date: Tue, 16 Feb 2021 12:37:10 +0100	[thread overview]
Message-ID: <20210216113716.716996-5-kraxel@redhat.com> (raw)
In-Reply-To: <20210216113716.716996-1-kraxel@redhat.com>

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@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


  parent reply	other threads:[~2021-02-16 11:42 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20210216113716.716996-1-kraxel@redhat.com>
2021-02-16 11:37 ` [PATCH 01/10] drm/qxl: properly handle device init failures Gerd Hoffmann
2021-02-16 13:08   ` Thomas Zimmermann
2021-02-16 11:37 ` [PATCH 02/10] drm/qxl: more fence wait rework Gerd Hoffmann
2021-02-16 11:37 ` [PATCH 03/10] drm/qxl: use ttm bo priorities Gerd Hoffmann
2021-02-16 11:37 ` Gerd Hoffmann [this message]
2021-02-16 11:37 ` [PATCH 05/10] drm/qxl: rename qxl_bo_kmap -> qxl_bo_kmap_locked Gerd Hoffmann
2021-02-16 13:14   ` Thomas Zimmermann
2021-02-16 11:37 ` [PATCH 06/10] drm/qxl: add qxl_bo_kmap/qxl_bo_kunmap Gerd Hoffmann
2021-02-16 13:17   ` Thomas Zimmermann
2021-02-16 11:37 ` [PATCH 07/10] drm/qxl: fix prime kmap Gerd Hoffmann
2021-02-16 13:16   ` Thomas Zimmermann
2021-02-16 11:37 ` [PATCH 08/10] drm/qxl: fix monitors object kmap Gerd Hoffmann
2021-02-16 13:18   ` Thomas Zimmermann
2021-02-16 11:37 ` [PATCH 09/10] drm/qxl: map/unmap framebuffers in prepare_fb+cleanup_fb callbacks Gerd Hoffmann
2021-02-16 13:27   ` Thomas Zimmermann
2021-02-16 13:46     ` Thomas Zimmermann
2021-02-17 10:02       ` Gerd Hoffmann
2021-02-17 10:23         ` Thomas Zimmermann
2021-02-16 11:37 ` [PATCH 10/10] drm/qxl: add lock asserts to qxl_bo_kmap_locked + qxl_bo_kunmap_locked Gerd Hoffmann
2021-02-16 13:30   ` Thomas Zimmermann

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