Hi Hans, I love your patch! Yet something to improve:
[auto build test ERROR on linus/master] [also build test ERROR on v4.19-rc2 next-20180906] [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/Hans-de-Goede/printk-For-early-boot-messages-check-loglevel-when-flushing-the-buffer/20180906-215356 config: parisc-allnoconfig (attached as .config) compiler: hppa-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree GCC_VERSION=7.2.0 make.cross ARCH=parisc All errors (new ones prefixed by >>): kernel/printk/printk.c: In function 'console_unlock': >> kernel/printk/printk.c:2377:5: error: implicit declaration of function >> 'suppress_message_printing' [-Werror=implicit-function-declaration] suppress_message_printing(msg->level))) { ^~~~~~~~~~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +/suppress_message_printing +2377 kernel/printk/printk.c 2297 2298 /** 2299 * console_unlock - unlock the console system 2300 * 2301 * Releases the console_lock which the caller holds on the console system 2302 * and the console driver list. 2303 * 2304 * While the console_lock was held, console output may have been buffered 2305 * by printk(). If this is the case, console_unlock(); emits 2306 * the output prior to releasing the lock. 2307 * 2308 * If there is output waiting, we wake /dev/kmsg and syslog() users. 2309 * 2310 * console_unlock(); may be called from any context. 2311 */ 2312 void console_unlock(void) 2313 { 2314 static char ext_text[CONSOLE_EXT_LOG_MAX]; 2315 static char text[LOG_LINE_MAX + PREFIX_MAX]; 2316 unsigned long flags; 2317 bool do_cond_resched, retry; 2318 2319 if (console_suspended) { 2320 up_console_sem(); 2321 return; 2322 } 2323 2324 /* 2325 * Console drivers are called with interrupts disabled, so 2326 * @console_may_schedule should be cleared before; however, we may 2327 * end up dumping a lot of lines, for example, if called from 2328 * console registration path, and should invoke cond_resched() 2329 * between lines if allowable. Not doing so can cause a very long 2330 * scheduling stall on a slow console leading to RCU stall and 2331 * softlockup warnings which exacerbate the issue with more 2332 * messages practically incapacitating the system. 2333 * 2334 * console_trylock() is not able to detect the preemptive 2335 * context reliably. Therefore the value must be stored before 2336 * and cleared after the the "again" goto label. 2337 */ 2338 do_cond_resched = console_may_schedule; 2339 again: 2340 console_may_schedule = 0; 2341 2342 /* 2343 * We released the console_sem lock, so we need to recheck if 2344 * cpu is online and (if not) is there at least one CON_ANYTIME 2345 * console. 2346 */ 2347 if (!can_use_console()) { 2348 console_locked = 0; 2349 up_console_sem(); 2350 return; 2351 } 2352 2353 for (;;) { 2354 struct printk_log *msg; 2355 size_t ext_len = 0; 2356 size_t len; 2357 2358 printk_safe_enter_irqsave(flags); 2359 raw_spin_lock(&logbuf_lock); 2360 if (console_seq < log_first_seq) { 2361 len = sprintf(text, "** %u printk messages dropped **\n", 2362 (unsigned)(log_first_seq - console_seq)); 2363 2364 /* messages are gone, move to first one */ 2365 console_seq = log_first_seq; 2366 console_idx = log_first_idx; 2367 } else { 2368 len = 0; 2369 } 2370 skip: 2371 if (console_seq == log_next_seq) 2372 break; 2373 2374 msg = log_from_idx(console_idx); 2375 if ((msg->flags & LOG_NOCONS) || 2376 ((msg->flags & LOG_CHK_LEVEL) && > 2377 suppress_message_printing(msg->level))) > { 2378 /* 2379 * Skip record if !ignore_loglevel, and 2380 * record has level above the console loglevel. 2381 */ 2382 console_idx = log_next(console_idx); 2383 console_seq++; 2384 goto skip; 2385 } 2386 2387 len += msg_print_text(msg, 2388 console_msg_format & MSG_FORMAT_SYSLOG, 2389 text + len, 2390 sizeof(text) - len); 2391 if (nr_ext_console_drivers) { 2392 ext_len = msg_print_ext_header(ext_text, 2393 sizeof(ext_text), 2394 msg, console_seq); 2395 ext_len += msg_print_ext_body(ext_text + ext_len, 2396 sizeof(ext_text) - ext_len, 2397 log_dict(msg), msg->dict_len, 2398 log_text(msg), msg->text_len); 2399 } 2400 console_idx = log_next(console_idx); 2401 console_seq++; 2402 raw_spin_unlock(&logbuf_lock); 2403 2404 /* 2405 * While actively printing out messages, if another printk() 2406 * were to occur on another CPU, it may wait for this one to 2407 * finish. This task can not be preempted if there is a 2408 * waiter waiting to take over. 2409 */ 2410 console_lock_spinning_enable(); 2411 2412 stop_critical_timings(); /* don't trace print latency */ 2413 call_console_drivers(ext_text, ext_len, text, len); 2414 start_critical_timings(); 2415 2416 if (console_lock_spinning_disable_and_check()) { 2417 printk_safe_exit_irqrestore(flags); 2418 return; 2419 } 2420 2421 printk_safe_exit_irqrestore(flags); 2422 2423 if (do_cond_resched) 2424 cond_resched(); 2425 } 2426 2427 console_locked = 0; 2428 2429 /* Release the exclusive_console once it is used */ 2430 if (unlikely(exclusive_console)) 2431 exclusive_console = NULL; 2432 2433 raw_spin_unlock(&logbuf_lock); 2434 2435 up_console_sem(); 2436 2437 /* 2438 * Someone could have filled up the buffer again, so re-check if there's 2439 * something to flush. In case we cannot trylock the console_sem again, 2440 * there's a new owner and the console_unlock() from them will do the 2441 * flush, no worries. 2442 */ 2443 raw_spin_lock(&logbuf_lock); 2444 retry = console_seq != log_next_seq; 2445 raw_spin_unlock(&logbuf_lock); 2446 printk_safe_exit_irqrestore(flags); 2447 2448 if (retry && console_trylock()) 2449 goto again; 2450 } 2451 EXPORT_SYMBOL(console_unlock); 2452 --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
.config.gz
Description: application/gzip
