From: Jeremy Cline <jcline@xxxxxxxxxx> commit abae9164a421bc4a41a3769f01ebcd1f9d955e0e upstream. Rather than protecting the nouveau_drm clients list with the lock within the "client" nouveau_cli, add a dedicated lock to serialize access to the list. This is both clearer and necessary to avoid lockdep being upset with us when we need to iterate through all the clients in the list and potentially lock their mutex, which is the same class as the lock protecting the entire list. Cc: stable@xxxxxxxxxxxxxxx # 5.4+ Signed-off-by: Jeremy Cline <jcline@xxxxxxxxxx> Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx> Reviewed-by: Ben Skeggs <bskeggs@xxxxxxxxxx> Tested-by: Karol Herbst <kherbst@xxxxxxxxxx> Signed-off-by: Karol Herbst <kherbst@xxxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20201125202648.5220-3-jcline@xxxxxxxxxx Link: https://gitlab.freedesktop.org/drm/nouveau/-/merge_requests/14 Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/nouveau/nouveau_drm.c | 10 ++++++---- drivers/gpu/drm/nouveau/nouveau_drv.h | 5 +++++ 2 files changed, 11 insertions(+), 4 deletions(-) --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -562,6 +562,7 @@ nouveau_drm_device_init(struct drm_devic nvkm_dbgopt(nouveau_debug, "DRM"); INIT_LIST_HEAD(&drm->clients); + mutex_init(&drm->clients_lock); spin_lock_init(&drm->tile.lock); /* workaround an odd issue on nvc1 by disabling the device's @@ -659,6 +660,7 @@ nouveau_drm_device_fini(struct drm_devic nouveau_cli_fini(&drm->client); nouveau_cli_fini(&drm->master); nvif_parent_dtor(&drm->parent); + mutex_destroy(&drm->clients_lock); kfree(drm); } @@ -1090,9 +1092,9 @@ nouveau_drm_open(struct drm_device *dev, fpriv->driver_priv = cli; - mutex_lock(&drm->client.mutex); + mutex_lock(&drm->clients_lock); list_add(&cli->head, &drm->clients); - mutex_unlock(&drm->client.mutex); + mutex_unlock(&drm->clients_lock); done: if (ret && cli) { @@ -1118,9 +1120,9 @@ nouveau_drm_postclose(struct drm_device nouveau_abi16_fini(cli->abi16); mutex_unlock(&cli->mutex); - mutex_lock(&drm->client.mutex); + mutex_lock(&drm->clients_lock); list_del(&cli->head); - mutex_unlock(&drm->client.mutex); + mutex_unlock(&drm->clients_lock); nouveau_cli_fini(cli); kfree(cli); --- a/drivers/gpu/drm/nouveau/nouveau_drv.h +++ b/drivers/gpu/drm/nouveau/nouveau_drv.h @@ -139,6 +139,11 @@ struct nouveau_drm { struct list_head clients; + /** + * @clients_lock: Protects access to the @clients list of &struct nouveau_cli. + */ + struct mutex clients_lock; + u8 old_pm_cap; struct {
