Hi Sergey, I love your patch! Yet something to improve:
[auto build test ERROR on linux-sof-driver/master] [also build test ERROR on v4.19 next-20181019] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Sergey-Senozhatsky/panic-avoid-deadlocks-in-re-entrant-console-drivers/20181025-181929 base: https://github.com/thesofproject/linux master config: i386-randconfig-x077-201842 (attached as .config) compiler: gcc-7 (Debian 7.3.0-1) 7.3.0 reproduce: # save the attached .config to linux build tree make ARCH=i386 All errors (new ones prefixed by >>): kernel/panic.c: In function 'panic': >> kernel/panic.c:237:2: error: implicit declaration of function >> 'unblank_screen' [-Werror=implicit-function-declaration] unblank_screen(); ^~~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +/unblank_screen +237 kernel/panic.c 186 187 /* 188 * If we have crashed and we have a crash kernel loaded let it handle 189 * everything else. 190 * If we want to run this after calling panic_notifiers, pass 191 * the "crash_kexec_post_notifiers" option to the kernel. 192 * 193 * Bypass the panic_cpu check and call __crash_kexec directly. 194 */ 195 if (!_crash_kexec_post_notifiers) { 196 printk_safe_flush_on_panic(); 197 __crash_kexec(NULL); 198 199 /* 200 * Note smp_send_stop is the usual smp shutdown function, which 201 * unfortunately means it may not be hardened to work in a 202 * panic situation. 203 */ 204 smp_send_stop(); 205 } else { 206 /* 207 * If we want to do crash dump after notifier calls and 208 * kmsg_dump, we will need architecture dependent extra 209 * works in addition to stopping other CPUs. 210 */ 211 crash_smp_send_stop(); 212 } 213 214 /* 215 * Run any panic handlers, including those that might need to 216 * add information to the kmsg dump output. 217 */ 218 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 219 220 /* Call flush even twice. It tries harder with a single online CPU */ 221 printk_safe_flush_on_panic(); 222 kmsg_dump(KMSG_DUMP_PANIC); 223 224 /* 225 * If you doubt kdump always works fine in any situation, 226 * "crash_kexec_post_notifiers" offers you a chance to run 227 * panic_notifiers and dumping kmsg before kdump. 228 * Note: since some panic_notifiers can make crashed kernel 229 * more unstable, it can increase risks of the kdump failure too. 230 * 231 * Bypass the panic_cpu check and call __crash_kexec directly. 232 */ 233 if (_crash_kexec_post_notifiers) 234 __crash_kexec(NULL); 235 236 #ifdef CONFIG_VT > 237 unblank_screen(); 238 #endif 239 console_unblank(); 240 241 /* 242 * We may have ended up stopping the CPU holding the lock (in 243 * smp_send_stop()) while still having some valuable data in the console 244 * buffer. Try to acquire the lock then release it regardless of the 245 * result. The release will also print the buffers out. Locks debug 246 * should be disabled to avoid reporting bad unlock balance when 247 * panic() is not being callled from OOPS. 248 */ 249 debug_locks_off(); 250 console_flush_on_panic(); 251 252 if (!panic_blink) 253 panic_blink = no_blink; 254 255 if (panic_timeout > 0) { 256 /* 257 * Delay timeout seconds before rebooting the machine. 258 * We can't use the "normal" timers since we just panicked. 259 */ 260 pr_emerg("Rebooting in %d seconds..\n", panic_timeout); 261 262 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { 263 touch_nmi_watchdog(); 264 if (i >= i_next) { 265 i += panic_blink(state ^= 1); 266 i_next = i + 3600 / PANIC_BLINK_SPD; 267 } 268 mdelay(PANIC_TIMER_STEP); 269 } 270 } 271 if (panic_timeout != 0) { 272 /* 273 * This will not be a clean reboot, with everything 274 * shutting down. But if there is a chance of 275 * rebooting the system it will be rebooted. 276 */ 277 emergency_restart(); 278 } 279 #ifdef __sparc__ 280 { 281 extern int stop_a_enabled; 282 /* Make sure the user can actually press Stop-A (L1-A) */ 283 stop_a_enabled = 1; 284 pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" 285 "twice on console to return to the boot prom\n"); 286 } 287 #endif 288 #if defined(CONFIG_S390) 289 { 290 unsigned long caller; 291 292 caller = (unsigned long)__builtin_return_address(0); 293 disabled_wait(caller); 294 } 295 #endif 296 pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf); 297 local_irq_enable(); 298 for (i = 0; ; i += PANIC_TIMER_STEP) { 299 touch_softlockup_watchdog(); 300 if (i >= i_next) { 301 i += panic_blink(state ^= 1); 302 i_next = i + 3600 / PANIC_BLINK_SPD; 303 } 304 mdelay(PANIC_TIMER_STEP); 305 } 306 } 307 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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