From ff7c60c580d9722f820d85c9c58ca55ecc1ee7c4 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 14 Jan 2013 15:08:14 +0100 Subject: [PATCH] drm/ttm: fix fence locking in ttm_buffer_object_transfer, 2nd try This fixes up commit e8e89622ed361c46bf90ba4828e685a8b603f7e5 Author: Daniel Vetter Date: Tue Dec 18 22:25:11 2012 +0100 drm/ttm: fix fence locking in ttm_buffer_object_transfer which leaves behind a might_sleep in atomic context, since the fence_lock spinlock is held over a kmalloc(GFP_KERNEL) call. The fix is to revert the above commit and only take the lock where we need it, around the call to ->sync_obj_ref. v2: Fixup things noticed by Maarten Lankhorst: - Brown paper bag locking bug. - No need for kzalloc if we clear the entire thing on the next line. - check for bo->sync_obj (totally unlikely race, but still someone else could have snuck in) and clear fbo->sync_obj if it's cleared already. Reported-by: Dave Airlie Cc: Jerome Glisse Cc: Maarten Lankhorst Signed-off-by: Daniel Vetter Signed-off-by: Dave Airlie --- drivers/gpu/drm/ttm/ttm_bo_util.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c index 44420fca7df..8be35c809c7 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -429,7 +429,7 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo, struct ttm_bo_device *bdev = bo->bdev; struct ttm_bo_driver *driver = bdev->driver; - fbo = kzalloc(sizeof(*fbo), GFP_KERNEL); + fbo = kmalloc(sizeof(*fbo), GFP_KERNEL); if (!fbo) return -ENOMEM; @@ -448,7 +448,12 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo, fbo->vm_node = NULL; atomic_set(&fbo->cpu_writers, 0); - fbo->sync_obj = driver->sync_obj_ref(bo->sync_obj); + spin_lock(&bdev->fence_lock); + if (bo->sync_obj) + fbo->sync_obj = driver->sync_obj_ref(bo->sync_obj); + else + fbo->sync_obj = NULL; + spin_unlock(&bdev->fence_lock); kref_init(&fbo->list_kref); kref_init(&fbo->kref); fbo->destroy = &ttm_transfered_destroy; @@ -661,13 +666,11 @@ int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo, */ set_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags); - - /* ttm_buffer_object_transfer accesses bo->sync_obj */ - ret = ttm_buffer_object_transfer(bo, &ghost_obj); spin_unlock(&bdev->fence_lock); if (tmp_obj) driver->sync_obj_unref(&tmp_obj); + ret = ttm_buffer_object_transfer(bo, &ghost_obj); if (ret) return ret;