Hi Petr, I love your patch! Yet something to improve: [auto build test ERROR on linus/master] [also build test ERROR on v4.18-rc4 next-20180709] [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/Petr-Mladek/printk-Fix-warning-about-unused-suppress_message_printing/20180710-174802 config: ia64-allnoconfig (attached as .config) compiler: ia64-linux-gcc (GCC) 8.1.0 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=8.1.0 make.cross ARCH=ia64 All errors (new ones prefixed by >>): kernel/printk/printk.c: In function 'console_unlock': >> kernel/printk/printk.c:2351:7: error: implicit declaration of function 'suppress_message_printing' [-Werror=implicit-function-declaration] if (suppress_message_printing(msg->level)) { ^~~~~~~~~~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +/suppress_message_printing +2351 kernel/printk/printk.c a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2273 ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2274 /** ac751efa6 kernel/printk.c Torben Hohn 2011-01-25 2275 * console_unlock - unlock the console system ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2276 * ac751efa6 kernel/printk.c Torben Hohn 2011-01-25 2277 * Releases the console_lock which the caller holds on the console system ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2278 * and the console driver list. ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2279 * ac751efa6 kernel/printk.c Torben Hohn 2011-01-25 2280 * While the console_lock was held, console output may have been buffered ac751efa6 kernel/printk.c Torben Hohn 2011-01-25 2281 * by printk(). If this is the case, console_unlock(); emits ac751efa6 kernel/printk.c Torben Hohn 2011-01-25 2282 * the output prior to releasing the lock. ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2283 * 7f3a781d6 kernel/printk.c Kay Sievers 2012-05-09 2284 * If there is output waiting, we wake /dev/kmsg and syslog() users. ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2285 * ac751efa6 kernel/printk.c Torben Hohn 2011-01-25 2286 * console_unlock(); may be called from any context. ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2287 */ ac751efa6 kernel/printk.c Torben Hohn 2011-01-25 2288 void console_unlock(void) ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2289 { 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2290 static char ext_text[CONSOLE_EXT_LOG_MAX]; 704982531 kernel/printk.c Kay Sievers 2012-07-16 2291 static char text[LOG_LINE_MAX + PREFIX_MAX]; ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2292 unsigned long flags; 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2293 bool do_cond_resched, retry; ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2294 557240b48 kernel/printk.c Linus Torvalds 2006-06-19 2295 if (console_suspended) { bd8d7cf5b kernel/printk/printk.c Jan Kara 2014-06-04 2296 up_console_sem(); 557240b48 kernel/printk.c Linus Torvalds 2006-06-19 2297 return; 557240b48 kernel/printk.c Linus Torvalds 2006-06-19 2298 } 78944e549 kernel/printk.c Antonino A. Daplas 2006-08-05 2299 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2300 /* 257ab4431 kernel/printk/printk.c Petr Mladek 2017-03-24 2301 * Console drivers are called with interrupts disabled, so 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2302 * @console_may_schedule should be cleared before; however, we may 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2303 * end up dumping a lot of lines, for example, if called from 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2304 * console registration path, and should invoke cond_resched() 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2305 * between lines if allowable. Not doing so can cause a very long 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2306 * scheduling stall on a slow console leading to RCU stall and 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2307 * softlockup warnings which exacerbate the issue with more 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2308 * messages practically incapacitating the system. 257ab4431 kernel/printk/printk.c Petr Mladek 2017-03-24 2309 * 257ab4431 kernel/printk/printk.c Petr Mladek 2017-03-24 2310 * console_trylock() is not able to detect the preemptive 257ab4431 kernel/printk/printk.c Petr Mladek 2017-03-24 2311 * context reliably. Therefore the value must be stored before 257ab4431 kernel/printk/printk.c Petr Mladek 2017-03-24 2312 * and cleared after the the "again" goto label. 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2313 */ 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2314 do_cond_resched = console_may_schedule; 257ab4431 kernel/printk/printk.c Petr Mladek 2017-03-24 2315 again: 78944e549 kernel/printk.c Antonino A. Daplas 2006-08-05 2316 console_may_schedule = 0; 78944e549 kernel/printk.c Antonino A. Daplas 2006-08-05 2317 a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2318 /* a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2319 * We released the console_sem lock, so we need to recheck if a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2320 * cpu is online and (if not) is there at least one CON_ANYTIME a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2321 * console. a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2322 */ a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2323 if (!can_use_console()) { a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2324 console_locked = 0; a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2325 up_console_sem(); a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2326 return; a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2327 } a8199371a kernel/printk/printk.c Sergey Senozhatsky 2016-03-17 2328 ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2329 for (;;) { 62e32ac35 kernel/printk/printk.c Joe Perches 2013-07-31 2330 struct printk_log *msg; 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2331 size_t ext_len = 0; 3ce9a7c0a kernel/printk.c Kay Sievers 2012-05-13 2332 size_t len; 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2333 f975237b7 kernel/printk/printk.c Sergey Senozhatsky 2016-12-27 2334 printk_safe_enter_irqsave(flags); f975237b7 kernel/printk/printk.c Sergey Senozhatsky 2016-12-27 2335 raw_spin_lock(&logbuf_lock); 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2336 if (console_seq < log_first_seq) { 9afe77ed8 kernel/printk/printk.c Maxim Akristiniy 2017-10-23 2337 len = sprintf(text, "** %u printk messages dropped **\n", 84b5ec8a9 kernel/printk/printk.c Will Deacon 2014-06-04 2338 (unsigned)(log_first_seq - console_seq)); 84b5ec8a9 kernel/printk/printk.c Will Deacon 2014-06-04 2339 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2340 /* messages are gone, move to first one */ 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2341 console_seq = log_first_seq; 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2342 console_idx = log_first_idx; 84b5ec8a9 kernel/printk/printk.c Will Deacon 2014-06-04 2343 } else { 84b5ec8a9 kernel/printk/printk.c Will Deacon 2014-06-04 2344 len = 0; 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2345 } 084681d14 kernel/printk.c Kay Sievers 2012-06-28 2346 skip: 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2347 if (console_seq == log_next_seq) 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2348 break; 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2349 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2350 msg = log_from_idx(console_idx); d9c23523e kernel/printk/printk.c Sergey Senozhatsky 2016-12-24 @2351 if (suppress_message_printing(msg->level)) { 084681d14 kernel/printk.c Kay Sievers 2012-06-28 2352 /* 084681d14 kernel/printk.c Kay Sievers 2012-06-28 2353 * Skip record we have buffered and already printed cf7754441 kernel/printk/printk.c Sergey Senozhatsky 2016-08-02 2354 * directly to the console when we received it, and cf7754441 kernel/printk/printk.c Sergey Senozhatsky 2016-08-02 2355 * record that has level above the console loglevel. 084681d14 kernel/printk.c Kay Sievers 2012-06-28 2356 */ 084681d14 kernel/printk.c Kay Sievers 2012-06-28 2357 console_idx = log_next(console_idx); 084681d14 kernel/printk.c Kay Sievers 2012-06-28 2358 console_seq++; 084681d14 kernel/printk.c Kay Sievers 2012-06-28 2359 goto skip; 084681d14 kernel/printk.c Kay Sievers 2012-06-28 2360 } 649e6ee33 kernel/printk.c Kay Sievers 2012-05-10 2361 cca10d58d kernel/printk/printk.c Sergey Senozhatsky 2017-12-21 2362 len += msg_print_text(msg, cca10d58d kernel/printk/printk.c Sergey Senozhatsky 2017-12-21 2363 console_msg_format & MSG_FORMAT_SYSLOG, cca10d58d kernel/printk/printk.c Sergey Senozhatsky 2017-12-21 2364 text + len, cca10d58d kernel/printk/printk.c Sergey Senozhatsky 2017-12-21 2365 sizeof(text) - len); 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2366 if (nr_ext_console_drivers) { 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2367 ext_len = msg_print_ext_header(ext_text, 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2368 sizeof(ext_text), 5aa068ea4 kernel/printk/printk.c Linus Torvalds 2016-10-25 2369 msg, console_seq); 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2370 ext_len += msg_print_ext_body(ext_text + ext_len, 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2371 sizeof(ext_text) - ext_len, 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2372 log_dict(msg), msg->dict_len, 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2373 log_text(msg), msg->text_len); 6fe29354b kernel/printk/printk.c Tejun Heo 2015-06-25 2374 } 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2375 console_idx = log_next(console_idx); 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2376 console_seq++; 07354eb1a kernel/printk.c Thomas Gleixner 2009-07-25 2377 raw_spin_unlock(&logbuf_lock); 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2378 dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2379) /* dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2380) * While actively printing out messages, if another printk() dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2381) * were to occur on another CPU, it may wait for this one to dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2382) * finish. This task can not be preempted if there is a dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2383) * waiter waiting to take over. dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2384) */ c162d5b43 kernel/printk/printk.c Petr Mladek 2018-01-12 2385 console_lock_spinning_enable(); dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2386) 81d68a96a kernel/printk.c Steven Rostedt 2008-05-12 2387 stop_critical_timings(); /* don't trace print latency */ d9c23523e kernel/printk/printk.c Sergey Senozhatsky 2016-12-24 2388 call_console_drivers(ext_text, ext_len, text, len); 81d68a96a kernel/printk.c Steven Rostedt 2008-05-12 2389 start_critical_timings(); dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2390) c162d5b43 kernel/printk/printk.c Petr Mladek 2018-01-12 2391 if (console_lock_spinning_disable_and_check()) { c162d5b43 kernel/printk/printk.c Petr Mladek 2018-01-12 2392 printk_safe_exit_irqrestore(flags); 43a17111c kernel/printk/printk.c Sergey Senozhatsky 2018-04-19 2393 return; c162d5b43 kernel/printk/printk.c Petr Mladek 2018-01-12 2394 } dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2395) f975237b7 kernel/printk/printk.c Sergey Senozhatsky 2016-12-27 2396 printk_safe_exit_irqrestore(flags); 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2397 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2398 if (do_cond_resched) 8d91f8b15 kernel/printk/printk.c Tejun Heo 2016-01-15 2399 cond_resched(); ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2400 } dbdda842f kernel/printk/printk.c Steven Rostedt (VMware 2018-01-10 2401) ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2402 console_locked = 0; fe3d8ad31 kernel/printk.c Feng Tang 2011-03-22 2403 fe3d8ad31 kernel/printk.c Feng Tang 2011-03-22 2404 /* Release the exclusive_console once it is used */ fe3d8ad31 kernel/printk.c Feng Tang 2011-03-22 2405 if (unlikely(exclusive_console)) fe3d8ad31 kernel/printk.c Feng Tang 2011-03-22 2406 exclusive_console = NULL; fe3d8ad31 kernel/printk.c Feng Tang 2011-03-22 2407 07354eb1a kernel/printk.c Thomas Gleixner 2009-07-25 2408 raw_spin_unlock(&logbuf_lock); 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2409 bd8d7cf5b kernel/printk/printk.c Jan Kara 2014-06-04 2410 up_console_sem(); 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2411 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2412 /* 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2413 * Someone could have filled up the buffer again, so re-check if there's 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2414 * something to flush. In case we cannot trylock the console_sem again, 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2415 * there's a new owner and the console_unlock() from them will do the 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2416 * flush, no worries. 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2417 */ 07354eb1a kernel/printk.c Thomas Gleixner 2009-07-25 2418 raw_spin_lock(&logbuf_lock); 7ff9554bb kernel/printk.c Kay Sievers 2012-05-03 2419 retry = console_seq != log_next_seq; f975237b7 kernel/printk/printk.c Sergey Senozhatsky 2016-12-27 2420 raw_spin_unlock(&logbuf_lock); f975237b7 kernel/printk/printk.c Sergey Senozhatsky 2016-12-27 2421 printk_safe_exit_irqrestore(flags); 09dc3cf93 kernel/printk.c Peter Zijlstra 2011-12-08 2422 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2423 if (retry && console_trylock()) 4f2a8d3cf kernel/printk.c Peter Zijlstra 2011-06-22 2424 goto again; ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2425 } ac751efa6 kernel/printk.c Torben Hohn 2011-01-25 2426 EXPORT_SYMBOL(console_unlock); ^1da177e4 kernel/printk.c Linus Torvalds 2005-04-16 2427 :::::: The code at line 2351 was first introduced by commit :::::: d9c23523ed98a3acaa0bfd8fef143595d6aa631d printk: drop call_console_drivers() unused param :::::: TO: Sergey Senozhatsky :::::: CC: Petr Mladek --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation