[bug report] drm/nouveau/gsp: add hal for gsp.get_static_info()

[Dan Carpenter]

[ Did these files get renamed or something?  No idea why the warnings
  are showing up as new now. ]

Hello Ben Skeggs,

Commit 7bb77eacdb85 ("drm/nouveau/gsp: add hal for
gsp.get_static_info()") from Nov 14, 2024 (linux-next), leads to the
following Smatch static checker warning:

drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/ctrl.c:47 r535_gsp_rpc_rm_ctrl_push() warn: passing zero to 'PTR_ERR'
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/gsp.c:223 r535_gsp_get_static_info() warn: 'rpc' can also be NULL
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r570/gsp.c:90 r570_gsp_get_static_info() warn: 'rpc' can also be NULL

drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/gsp.c
    212 static int
    213 r535_gsp_get_static_info(struct nvkm_gsp *gsp)
    214 {
    215         GspStaticConfigInfo *rpc;
    216 
    217         rpc = nvkm_gsp_rpc_rd(gsp, NV_VGPU_MSG_FUNCTION_GET_GSP_STATIC_INFO, sizeof(*rpc));
    218         if (IS_ERR(rpc))
    219                 return PTR_ERR(rpc);
    220 
    221         gsp->internal.client.object.client = &gsp->internal.client;
    222         gsp->internal.client.object.parent = NULL;
--> 223         gsp->internal.client.object.handle = rpc->hInternalClient;
                                                     ^^^^^

The nvkm_gsp_rpc_rd() function returns a mix of error pointers and NULL but
if it returns NULL then obviously this dereference will crash.

https://staticthinking.wordpress.com/2022/08/01/mixing-error-pointers-and-null/

regards,
dan carpenter