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Message-ID: <202509050404.ZLQknagH-lkp@intel.com>
Date: Fri, 5 Sep 2025 04:29:17 +0800
From: kernel test robot <lkp@...el.com>
To: Vincent Mailhol <mailhol@...nel.org>,
Marc Kleine-Budde <mkl@...gutronix.de>,
Oliver Hartkopp <socketcan@...tkopp.net>
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
Vincent Mailhol <mailhol@...nel.org>,
Stéphane Grosjean <stephane.grosjean@...-networks.com>,
Robert Nawrath <mbro1689@...il.com>,
Minh Le <minh.le.aj@...esas.com>,
Duy Nguyen <duy.nguyen.rh@...esas.com>, linux-can@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/21] can: netlink: add can_dtb_changelink()
Hi Vincent,
kernel test robot noticed the following build warnings:
[auto build test WARNING on 2fd4161d0d2547650d9559d57fc67b4e0a26a9e3]
url: https://github.com/intel-lab-lkp/linux/commits/Vincent-Mailhol/can-dev-move-struct-data_bittiming_params-to-linux-can-bittiming-h/20250903-170807
base: 2fd4161d0d2547650d9559d57fc67b4e0a26a9e3
patch link: https://lore.kernel.org/r/20250903-canxl-netlink-prep-v1-11-904bd6037cd9%40kernel.org
patch subject: [PATCH 11/21] can: netlink: add can_dtb_changelink()
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20250905/202509050404.ZLQknagH-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250905/202509050404.ZLQknagH-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202509050404.ZLQknagH-lkp@intel.com/
All warnings (new ones prefixed by >>):
drivers/net/can/dev/netlink.c:111:6: warning: variable 'is_on' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
111 | if (ifla_can_data_bittiming == IFLA_CAN_DATA_BITTIMING) {
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/can/dev/netlink.c:119:6: note: uninitialized use occurs here
119 | if (is_on) {
| ^~~~~
drivers/net/can/dev/netlink.c:111:2: note: remove the 'if' if its condition is always true
111 | if (ifla_can_data_bittiming == IFLA_CAN_DATA_BITTIMING) {
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
112 | data_tdc = data[IFLA_CAN_TDC];
113 | tdc_flags = flags & CAN_CTRLMODE_FD_TDC_MASK;
114 | is_on = flags & CAN_CTRLMODE_FD;
115 | } else {
| ~~~~~~
116 | WARN_ON(1); /* Place holder for CAN XL */
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
117 | }
| ~
drivers/net/can/dev/netlink.c:108:12: note: initialize the variable 'is_on' to silence this warning
108 | bool is_on;
| ^
| = 0
>> drivers/net/can/dev/netlink.c:227:6: warning: variable 'data_bittiming' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
227 | if (fd) {
| ^~
drivers/net/can/dev/netlink.c:236:7: note: uninitialized use occurs here
236 | if (!data_bittiming)
| ^~~~~~~~~~~~~~
drivers/net/can/dev/netlink.c:227:2: note: remove the 'if' if its condition is always true
227 | if (fd) {
| ^~~~~~~
228 | data_bittiming = data[IFLA_CAN_DATA_BITTIMING];
229 | data_tdc = data[IFLA_CAN_TDC];
230 | dbt_params = &priv->fd;
231 | tdc_mask = CAN_CTRLMODE_FD_TDC_MASK;
232 | } else {
| ~~~~~~
233 | WARN_ON(1); /* Place holder for CAN XL */
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
234 | }
| ~
drivers/net/can/dev/netlink.c:219:31: note: initialize the variable 'data_bittiming' to silence this warning
219 | struct nlattr *data_bittiming, *data_tdc;
| ^
| = NULL
2 warnings generated.
vim +227 drivers/net/can/dev/netlink.c
215
216 static int can_dbt_changelink(struct net_device *dev, struct nlattr *data[],
217 bool fd, struct netlink_ext_ack *extack)
218 {
219 struct nlattr *data_bittiming, *data_tdc;
220 struct can_priv *priv = netdev_priv(dev);
221 struct data_bittiming_params *dbt_params;
222 struct can_bittiming dbt;
223 bool need_tdc_calc = false;
224 u32 tdc_mask;
225 int err;
226
> 227 if (fd) {
228 data_bittiming = data[IFLA_CAN_DATA_BITTIMING];
229 data_tdc = data[IFLA_CAN_TDC];
230 dbt_params = &priv->fd;
231 tdc_mask = CAN_CTRLMODE_FD_TDC_MASK;
232 } else {
233 WARN_ON(1); /* Place holder for CAN XL */
234 }
235
236 if (!data_bittiming)
237 return 0;
238
239 /* Do not allow changing bittiming while running */
240 if (dev->flags & IFF_UP)
241 return -EBUSY;
242
243 /* Calculate bittiming parameters based on data_bittiming_const
244 * if set, otherwise pass bitrate directly via do_set_bitrate().
245 * Bail out if neither is given.
246 */
247 if (!dbt_params->data_bittiming_const && !dbt_params->do_set_data_bittiming &&
248 !dbt_params->data_bitrate_const)
249 return -EOPNOTSUPP;
250
251 memcpy(&dbt, nla_data(data_bittiming), sizeof(dbt));
252 err = can_get_bittiming(dev, &dbt, dbt_params->data_bittiming_const,
253 dbt_params->data_bitrate_const,
254 dbt_params->data_bitrate_const_cnt, extack);
255 if (err)
256 return err;
257
258 if (priv->bitrate_max && dbt.bitrate > priv->bitrate_max) {
259 NL_SET_ERR_MSG_FMT(extack,
260 "CAN data bitrate %u bps surpasses transceiver capabilities of %u bps",
261 dbt.bitrate, priv->bitrate_max);
262 return -EINVAL;
263 }
264
265 memset(&dbt_params->tdc, 0, sizeof(dbt_params->tdc));
266 if (data[IFLA_CAN_CTRLMODE]) {
267 struct can_ctrlmode *cm = nla_data(data[IFLA_CAN_CTRLMODE]);
268
269 need_tdc_calc = !(cm->mask & tdc_mask);
270 }
271 if (data_tdc) {
272 /* TDC parameters are provided: use them */
273 err = can_tdc_changelink(dbt_params, data_tdc, extack);
274 if (err) {
275 priv->ctrlmode &= ~tdc_mask;
276 return err;
277 }
278 } else if (need_tdc_calc) {
279 /* Neither of TDC parameters nor TDC flags are provided:
280 * do calculation
281 */
282 can_calc_tdco(&dbt_params->tdc, dbt_params->tdc_const, &dbt,
283 &priv->ctrlmode, priv->ctrlmode_supported);
284 } /* else: both CAN_CTRLMODE_TDC_{AUTO,MANUAL} are explicitly
285 * turned off. TDC is disabled: do nothing
286 */
287
288 memcpy(&dbt_params->data_bittiming, &dbt, sizeof(dbt));
289
290 if (dbt_params->do_set_data_bittiming) {
291 /* Finally, set the bit-timing registers */
292 err = dbt_params->do_set_data_bittiming(dev);
293 if (err)
294 return err;
295 }
296
297 return 0;
298 }
299
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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