Re: [cxl:preview 48/67] drivers/cxl/core/pci.c:302 __cxl_hdm_decode_init() warn: ignoring unreachable code.

From: Ira Weiny
Date: Mon May 16 2022 - 16:35:37 EST

On Mon, May 16, 2022 at 02:14:38PM +0300, Dan Carpenter wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl.git preview
> head: 9c642abd8b31d895f34186bd72b7360083b58492
> commit: 2263e9ed65887cc7c6e977f372596199d2c9f4af [48/67] cxl/port: Enable HDM Capability after validating DVSEC Ranges
> config: x86_64-randconfig-m001-20220509 (https://download.01.org/0day-ci/archive/20220513/202205130114.DpEOzjJn-lkp@xxxxxxxxx/config)
> compiler: gcc-11 (Debian 11.2.0-20) 11.2.0
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

Thanks great catch!

Ira

>
> smatch warnings:
> drivers/cxl/core/pci.c:302 __cxl_hdm_decode_init() warn: ignoring unreachable code.
>
> vim +302 drivers/cxl/core/pci.c
>
> 18e7a07f5d584d Dan Williams 2022-05-01 270 static bool __cxl_hdm_decode_init(struct cxl_dev_state *cxlds,
> 9382da4f1fd2c2 Dan Williams 2022-05-09 271 struct cxl_hdm *cxlhdm,
> 18e7a07f5d584d Dan Williams 2022-05-01 272 struct cxl_endpoint_dvsec_info *info)
> 18e7a07f5d584d Dan Williams 2022-05-01 273 {
> 9382da4f1fd2c2 Dan Williams 2022-05-09 274 void __iomem *hdm = cxlhdm->regs.hdm_decoder;
> 2263e9ed65887c Dan Williams 2022-05-10 275 struct cxl_port *port = cxlhdm->port;
> 2263e9ed65887c Dan Williams 2022-05-10 276 struct device *dev = cxlds->dev;
> 2263e9ed65887c Dan Williams 2022-05-10 277 struct cxl_port *root;
> 18e7a07f5d584d Dan Williams 2022-05-01 278 u32 global_ctrl;
> 2263e9ed65887c Dan Williams 2022-05-10 279 int i, rc;
> 18e7a07f5d584d Dan Williams 2022-05-01 280
> 9382da4f1fd2c2 Dan Williams 2022-05-09 281 global_ctrl = readl(hdm + CXL_HDM_DECODER_CTRL_OFFSET);
> 18e7a07f5d584d Dan Williams 2022-05-01 282
> 2263e9ed65887c Dan Williams 2022-05-10 283 /*
> 2263e9ed65887c Dan Williams 2022-05-10 284 * If the HDM Decoder Capability is already enabled then assume
> 2263e9ed65887c Dan Williams 2022-05-10 285 * that some other agent like platform firmware set it up.
> 2263e9ed65887c Dan Williams 2022-05-10 286 */
> 2263e9ed65887c Dan Williams 2022-05-10 287 if (global_ctrl & CXL_HDM_DECODER_ENABLE) {
> 2263e9ed65887c Dan Williams 2022-05-10 288 rc = devm_cxl_enable_mem(&port->dev, cxlds);
> 2263e9ed65887c Dan Williams 2022-05-10 289 if (rc)
> 9382da4f1fd2c2 Dan Williams 2022-05-09 290 return false;
> 2263e9ed65887c Dan Williams 2022-05-10 291 return true;
> 2263e9ed65887c Dan Williams 2022-05-10 292 }
> 2263e9ed65887c Dan Williams 2022-05-10 293
> 2263e9ed65887c Dan Williams 2022-05-10 294 root = to_cxl_port(port->dev.parent);
> 2263e9ed65887c Dan Williams 2022-05-10 295 while (!is_cxl_root(root) && is_cxl_port(root->dev.parent))
> 2263e9ed65887c Dan Williams 2022-05-10 296 root = to_cxl_port(root->dev.parent);
> 2263e9ed65887c Dan Williams 2022-05-10 297 if (!is_cxl_root(root)) {
> 2263e9ed65887c Dan Williams 2022-05-10 298 dev_err(dev, "Failed to acquire root port for HDM enable\n");
> 2263e9ed65887c Dan Williams 2022-05-10 299 return false;
> 2263e9ed65887c Dan Williams 2022-05-10 300 }
> 2263e9ed65887c Dan Williams 2022-05-10 301
> 2263e9ed65887c Dan Williams 2022-05-10 @302 for (i = 0; i < info->ranges; i++) {
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This only loops once. if (info->ranges != 0) {?
>
>
> 2263e9ed65887c Dan Williams 2022-05-10 303 struct device *cxld_dev;
> 2263e9ed65887c Dan Williams 2022-05-10 304
> 2263e9ed65887c Dan Williams 2022-05-10 305 if (!info->mem_enabled)
> 2263e9ed65887c Dan Williams 2022-05-10 306 break;
> 2263e9ed65887c Dan Williams 2022-05-10 307
> 2263e9ed65887c Dan Williams 2022-05-10 308 cxld_dev = device_find_child(&root->dev, &info->dvsec_range[i],
> 2263e9ed65887c Dan Williams 2022-05-10 309 dvsec_range_allowed);
> 2263e9ed65887c Dan Williams 2022-05-10 310 if (!cxld_dev) {
> 2263e9ed65887c Dan Williams 2022-05-10 311 dev_dbg(dev, "Range%d disallowed by platform\n", i);
> 2263e9ed65887c Dan Williams 2022-05-10 312 cxl_set_mem_enable(cxlds, 0);
> 2263e9ed65887c Dan Williams 2022-05-10 313 info->mem_enabled = 0;
> 2263e9ed65887c Dan Williams 2022-05-10 314 break;
> 2263e9ed65887c Dan Williams 2022-05-10 315 }
> 2263e9ed65887c Dan Williams 2022-05-10 316 put_device(cxld_dev);
> 2263e9ed65887c Dan Williams 2022-05-10 317 break;
>
> Or delete this break?
>
> 2263e9ed65887c Dan Williams 2022-05-10 318 }
> 2263e9ed65887c Dan Williams 2022-05-10 319 put_device(&root->dev);
> 18e7a07f5d584d Dan Williams 2022-05-01 320
> 87aafd75cc537f Dan Williams 2022-04-30 321 /*
> 2263e9ed65887c Dan Williams 2022-05-10 322 * At least one DVSEC range is enabled and allowed, skip HDM
> 2263e9ed65887c Dan Williams 2022-05-10 323 * Decoder Capability Enable
> 87aafd75cc537f Dan Williams 2022-04-30 324 */
> 2263e9ed65887c Dan Williams 2022-05-10 325 if (info->mem_enabled)
> 2263e9ed65887c Dan Williams 2022-05-10 326 return false;
> 2263e9ed65887c Dan Williams 2022-05-10 327
> 2263e9ed65887c Dan Williams 2022-05-10 328 rc = devm_cxl_enable_hdm(&port->dev, cxlhdm);
> 2263e9ed65887c Dan Williams 2022-05-10 329 if (rc)
> 2263e9ed65887c Dan Williams 2022-05-10 330 return false;
> 2263e9ed65887c Dan Williams 2022-05-10 331
> 2263e9ed65887c Dan Williams 2022-05-10 332 rc = devm_cxl_enable_mem(&port->dev, cxlds);
> 2263e9ed65887c Dan Williams 2022-05-10 333 if (rc)
> 2263e9ed65887c Dan Williams 2022-05-10 334 return false;
> 18e7a07f5d584d Dan Williams 2022-05-01 335
> 9382da4f1fd2c2 Dan Williams 2022-05-09 336 return true;
> 18e7a07f5d584d Dan Williams 2022-05-01 337 }
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp
>