[gustavoars-linux:for-next/clang-fallthrough 4/4] arch/mips/kernel/idle.c:206:3: warning: fallthrough annotation in unreachable code

From: kernel test robot
Date: Mon Jul 26 2021 - 22:40:11 EST

tree: https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git for-next/clang-fallthrough
head: 6a8c3492420661bf905f0f1f4cddde0ec8bde6d8
commit: 6a8c3492420661bf905f0f1f4cddde0ec8bde6d8 [4/4] Revert "Revert "Makefile: Enable -Wimplicit-fallthrough for Clang""
config: mips-randconfig-r036-20210726 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project c658b472f3e61e1818e1909bf02f3d65470018a5)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install mips cross compiling tool for clang build
# apt-get install binutils-mips-linux-gnu
# https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git/commit/?id=6a8c3492420661bf905f0f1f4cddde0ec8bde6d8
git remote add gustavoars-linux https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git
git fetch --no-tags gustavoars-linux for-next/clang-fallthrough
git checkout 6a8c3492420661bf905f0f1f4cddde0ec8bde6d8
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> arch/mips/kernel/idle.c:206:3: warning: fallthrough annotation in unreachable code [-Wimplicit-fallthrough]
fallthrough;
^
include/linux/compiler_attributes.h:210:41: note: expanded from macro 'fallthrough'
# define fallthrough __attribute__((__fallthrough__))
^
1 warning generated.


vim +206 arch/mips/kernel/idle.c

49f2ec91e14ce9 Ralf Baechle 2013-05-21 125
49f2ec91e14ce9 Ralf Baechle 2013-05-21 126 void __init check_wait(void)
49f2ec91e14ce9 Ralf Baechle 2013-05-21 127 {
49f2ec91e14ce9 Ralf Baechle 2013-05-21 128 struct cpuinfo_mips *c = &current_cpu_data;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 129
49f2ec91e14ce9 Ralf Baechle 2013-05-21 130 if (nowait) {
49f2ec91e14ce9 Ralf Baechle 2013-05-21 131 printk("Wait instruction disabled.\n");
49f2ec91e14ce9 Ralf Baechle 2013-05-21 132 return;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 133 }
49f2ec91e14ce9 Ralf Baechle 2013-05-21 134
5b10a0e84b4ebe Paul Burton 2015-09-22 135 /*
5b10a0e84b4ebe Paul Burton 2015-09-22 136 * MIPSr6 specifies that masked interrupts should unblock an executing
5b10a0e84b4ebe Paul Burton 2015-09-22 137 * wait instruction, and thus that it is safe for us to use
5b10a0e84b4ebe Paul Burton 2015-09-22 138 * r4k_wait_irqoff. Yippee!
5b10a0e84b4ebe Paul Burton 2015-09-22 139 */
5b10a0e84b4ebe Paul Burton 2015-09-22 140 if (cpu_has_mips_r6) {
5b10a0e84b4ebe Paul Burton 2015-09-22 141 cpu_wait = r4k_wait_irqoff;
5b10a0e84b4ebe Paul Burton 2015-09-22 142 return;
5b10a0e84b4ebe Paul Burton 2015-09-22 143 }
5b10a0e84b4ebe Paul Burton 2015-09-22 144
69f24d1784b631 Ralf Baechle 2013-09-17 145 switch (current_cpu_type()) {
49f2ec91e14ce9 Ralf Baechle 2013-05-21 146 case CPU_R3081:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 147 case CPU_R3081E:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 148 cpu_wait = r3081_wait;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 149 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 150 case CPU_TX3927:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 151 cpu_wait = r39xx_wait;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 152 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 153 case CPU_R4200:
65ce6197ed403b Lauri Kasanen 2021-01-13 154 /* case CPU_R4300: */
49f2ec91e14ce9 Ralf Baechle 2013-05-21 155 case CPU_R4600:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 156 case CPU_R4640:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 157 case CPU_R4650:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 158 case CPU_R4700:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 159 case CPU_R5000:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 160 case CPU_R5500:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 161 case CPU_NEVADA:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 162 case CPU_4KC:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 163 case CPU_4KEC:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 164 case CPU_4KSC:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 165 case CPU_5KC:
bf463f2f751077 Aurelien Jarno 2015-09-05 166 case CPU_5KE:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 167 case CPU_25KF:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 168 case CPU_PR4450:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 169 case CPU_BMIPS3300:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 170 case CPU_BMIPS4350:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 171 case CPU_BMIPS4380:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 172 case CPU_CAVIUM_OCTEON:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 173 case CPU_CAVIUM_OCTEON_PLUS:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 174 case CPU_CAVIUM_OCTEON2:
4122af0ab02a4b David Daney 2013-07-29 175 case CPU_CAVIUM_OCTEON3:
3b25b763116482 Paul Cercueil 2019-05-08 176 case CPU_XBURST:
b2afb64cccd243 Huacai Chen 2019-11-04 177 case CPU_LOONGSON32:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 178 case CPU_XLR:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 179 case CPU_XLP:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 180 cpu_wait = r4k_wait;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 181 break;
268a2d60013049 Jiaxun Yang 2019-10-20 182 case CPU_LOONGSON64:
7507445b199308 Huacai Chen 2019-09-21 183 if ((c->processor_id & (PRID_IMP_MASK | PRID_REV_MASK)) >=
0cf2ea1121aa14 Jiaxun Yang 2020-04-22 184 (PRID_IMP_LOONGSON_64C | PRID_REV_LOONGSON3A_R2_0) ||
0cf2ea1121aa14 Jiaxun Yang 2020-04-22 185 (c->processor_id & PRID_IMP_MASK) == PRID_IMP_LOONGSON_64R)
b2edcfc814017e Huacai Chen 2016-03-03 186 cpu_wait = r4k_wait;
b2edcfc814017e Huacai Chen 2016-03-03 187 break;
b2edcfc814017e Huacai Chen 2016-03-03 188
adaa0b6c497955 Petri Gynther 2015-10-19 189 case CPU_BMIPS5000:
adaa0b6c497955 Petri Gynther 2015-10-19 190 cpu_wait = r4k_wait_irqoff;
adaa0b6c497955 Petri Gynther 2015-10-19 191 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 192 case CPU_RM7000:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 193 cpu_wait = rm7k_wait_irqoff;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 194 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 195
e38df288a9db56 James Hogan 2015-01-29 196 case CPU_PROAPTIV:
e38df288a9db56 James Hogan 2015-01-29 197 case CPU_P5600:
e38df288a9db56 James Hogan 2015-01-29 198 /*
e38df288a9db56 James Hogan 2015-01-29 199 * Incoming Fast Debug Channel (FDC) data during a wait
e38df288a9db56 James Hogan 2015-01-29 200 * instruction causes the wait never to resume, even if an
e38df288a9db56 James Hogan 2015-01-29 201 * interrupt is received. Avoid using wait at all if FDC data is
e38df288a9db56 James Hogan 2015-01-29 202 * likely to be received.
e38df288a9db56 James Hogan 2015-01-29 203 */
e38df288a9db56 James Hogan 2015-01-29 204 if (IS_ENABLED(CONFIG_MIPS_EJTAG_FDC_TTY))
e38df288a9db56 James Hogan 2015-01-29 205 break;
c9b0299034665d Liangliang Huang 2020-05-04 @206 fallthrough;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 207 case CPU_M14KC:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 208 case CPU_M14KEC:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 209 case CPU_24K:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 210 case CPU_34K:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 211 case CPU_1004K:
442e14a2c55e55 Steven J. Hill 2014-01-17 212 case CPU_1074K:
26ab96dfa9f98d Leonid Yegoshin 2013-11-27 213 case CPU_INTERAPTIV:
f36c4720fca325 Leonid Yegoshin 2014-03-04 214 case CPU_M5150:
4695089f03929c Leonid Yegoshin 2014-11-24 215 case CPU_QEMU_GENERIC:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 216 cpu_wait = r4k_wait;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 217 if (read_c0_config7() & MIPS_CONF7_WII)
49f2ec91e14ce9 Ralf Baechle 2013-05-21 218 cpu_wait = r4k_wait_irqoff;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 219 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 220
49f2ec91e14ce9 Ralf Baechle 2013-05-21 221 case CPU_74K:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 222 cpu_wait = r4k_wait;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 223 if ((c->processor_id & 0xff) >= PRID_REV_ENCODE_332(2, 1, 0))
49f2ec91e14ce9 Ralf Baechle 2013-05-21 224 cpu_wait = r4k_wait_irqoff;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 225 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 226
49f2ec91e14ce9 Ralf Baechle 2013-05-21 227 case CPU_TX49XX:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 228 cpu_wait = r4k_wait_irqoff;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 229 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 230 case CPU_ALCHEMY:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 231 cpu_wait = au1k_wait;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 232 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 233 case CPU_20KC:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 234 /*
49f2ec91e14ce9 Ralf Baechle 2013-05-21 235 * WAIT on Rev1.0 has E1, E2, E3 and E16.
49f2ec91e14ce9 Ralf Baechle 2013-05-21 236 * WAIT on Rev2.0 and Rev3.0 has E16.
49f2ec91e14ce9 Ralf Baechle 2013-05-21 237 * Rev3.1 WAIT is nop, why bother
49f2ec91e14ce9 Ralf Baechle 2013-05-21 238 */
49f2ec91e14ce9 Ralf Baechle 2013-05-21 239 if ((c->processor_id & 0xff) <= 0x64)
49f2ec91e14ce9 Ralf Baechle 2013-05-21 240 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 241
49f2ec91e14ce9 Ralf Baechle 2013-05-21 242 /*
49f2ec91e14ce9 Ralf Baechle 2013-05-21 243 * Another rev is incremeting c0_count at a reduced clock
49f2ec91e14ce9 Ralf Baechle 2013-05-21 244 * rate while in WAIT mode. So we basically have the choice
49f2ec91e14ce9 Ralf Baechle 2013-05-21 245 * between using the cp0 timer as clocksource or avoiding
49f2ec91e14ce9 Ralf Baechle 2013-05-21 246 * the WAIT instruction. Until more details are known,
49f2ec91e14ce9 Ralf Baechle 2013-05-21 247 * disable the use of WAIT for 20Kc entirely.
49f2ec91e14ce9 Ralf Baechle 2013-05-21 248 cpu_wait = r4k_wait;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 249 */
49f2ec91e14ce9 Ralf Baechle 2013-05-21 250 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 251 default:
49f2ec91e14ce9 Ralf Baechle 2013-05-21 252 break;
49f2ec91e14ce9 Ralf Baechle 2013-05-21 253 }
49f2ec91e14ce9 Ralf Baechle 2013-05-21 254 }
49f2ec91e14ce9 Ralf Baechle 2013-05-21 255

:::::: The code at line 206 was first introduced by commit
:::::: c9b0299034665d594e56ee343f28033d1b24de6d MIPS: Use fallthrough for arch/mips

:::::: TO: Liangliang Huang <huanglllzu@xxxxxxxxx>
:::::: CC: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

Attachment: .config.gz
Description: application/gzip