CC: kbuild-...@lists.01.org CC: linux-ker...@vger.kernel.org TO: "Paul, E., McKenney," <paul...@kernel.org>
tree: https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2020.05.26b head: 795279db1396bf66621fa3f343fa990fe543b89e commit: 7e2a6278a303f510883b32c1ac2d5ea7351b7e1d [59/70] refperf: Dynamically allocate experiment-summary output buffer :::::: branch date: 6 days ago :::::: commit date: 6 days ago config: x86_64-randconfig-m001-20200602 (attached as .config) compiler: gcc-9 (Debian 9.3.0-13) 9.3.0 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <l...@intel.com> Reported-by: Dan Carpenter <dan.carpen...@oracle.com> smatch warnings: kernel/rcu/refperf.c:391 main_func() error: we previously assumed 'buf' could be null (see line 348) # https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=7e2a6278a303f510883b32c1ac2d5ea7351b7e1d git remote add rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git git remote update rcu git checkout 7e2a6278a303f510883b32c1ac2d5ea7351b7e1d vim +/buf +391 kernel/rcu/refperf.c 786a2549774369 Joel Fernandes (Google 2020-05-25 325) 786a2549774369 Joel Fernandes (Google 2020-05-25 326) // The main_func is the main orchestrator, it performs a bunch of 786a2549774369 Joel Fernandes (Google 2020-05-25 327) // experiments. For every experiment, it orders all the readers 786a2549774369 Joel Fernandes (Google 2020-05-25 328) // involved to start and waits for them to finish the experiment. It 786a2549774369 Joel Fernandes (Google 2020-05-25 329) // then reads their timestamps and starts the next experiment. Each 786a2549774369 Joel Fernandes (Google 2020-05-25 330) // experiment progresses from 1 concurrent reader to N of them at which 786a2549774369 Joel Fernandes (Google 2020-05-25 331) // point all the timestamps are printed. 786a2549774369 Joel Fernandes (Google 2020-05-25 332) static int main_func(void *arg) 786a2549774369 Joel Fernandes (Google 2020-05-25 333) { 7e2a6278a303f5 Paul E. McKenney 2020-05-25 334 bool errexit = false; 786a2549774369 Joel Fernandes (Google 2020-05-25 335) int exp, r; 786a2549774369 Joel Fernandes (Google 2020-05-25 336) char buf1[64]; 7e2a6278a303f5 Paul E. McKenney 2020-05-25 337 char *buf; e4c9f422a8f55a Paul E. McKenney 2020-05-25 338 u64 *result_avg; 786a2549774369 Joel Fernandes (Google 2020-05-25 339) 786a2549774369 Joel Fernandes (Google 2020-05-25 340) set_cpus_allowed_ptr(current, cpumask_of(nreaders % nr_cpu_ids)); 786a2549774369 Joel Fernandes (Google 2020-05-25 341) set_user_nice(current, MAX_NICE); 786a2549774369 Joel Fernandes (Google 2020-05-25 342) 0df40fd6b88e49 Paul E. McKenney 2020-05-25 343 if (holdoff) 0df40fd6b88e49 Paul E. McKenney 2020-05-25 344 schedule_timeout_interruptible(holdoff * HZ); 786a2549774369 Joel Fernandes (Google 2020-05-25 345) VERBOSE_PERFOUT("main_func task started"); e4c9f422a8f55a Paul E. McKenney 2020-05-25 346 result_avg = kzalloc(nruns * sizeof(*result_avg), GFP_KERNEL); 7e2a6278a303f5 Paul E. McKenney 2020-05-25 347 buf = kzalloc(64 + nruns * 32, GFP_KERNEL); 7e2a6278a303f5 Paul E. McKenney 2020-05-25 @348 if (!result_avg || !buf) { e4c9f422a8f55a Paul E. McKenney 2020-05-25 349 VERBOSE_PERFOUT_ERRSTRING("out of memory"); 7e2a6278a303f5 Paul E. McKenney 2020-05-25 350 errexit = true; 7e2a6278a303f5 Paul E. McKenney 2020-05-25 351 } 786a2549774369 Joel Fernandes (Google 2020-05-25 352) atomic_inc(&n_init); 786a2549774369 Joel Fernandes (Google 2020-05-25 353) 786a2549774369 Joel Fernandes (Google 2020-05-25 354) // Wait for all threads to start. 786a2549774369 Joel Fernandes (Google 2020-05-25 355) wait_event(main_wq, atomic_read(&n_init) == (nreaders + 1)); 786a2549774369 Joel Fernandes (Google 2020-05-25 356) 786a2549774369 Joel Fernandes (Google 2020-05-25 357) // Start exp readers up per experiment e4c9f422a8f55a Paul E. McKenney 2020-05-25 358 for (exp = 0; exp < nruns && !torture_must_stop(); exp++) { 7e2a6278a303f5 Paul E. McKenney 2020-05-25 359 if (errexit) e4c9f422a8f55a Paul E. McKenney 2020-05-25 360 break; 786a2549774369 Joel Fernandes (Google 2020-05-25 361) if (torture_must_stop()) 786a2549774369 Joel Fernandes (Google 2020-05-25 362) goto end; 786a2549774369 Joel Fernandes (Google 2020-05-25 363) e4c9f422a8f55a Paul E. McKenney 2020-05-25 364 reset_readers(); e4c9f422a8f55a Paul E. McKenney 2020-05-25 365 atomic_set(&nreaders_exp, nreaders); 786a2549774369 Joel Fernandes (Google 2020-05-25 366) 786a2549774369 Joel Fernandes (Google 2020-05-25 367) exp_idx = exp; 786a2549774369 Joel Fernandes (Google 2020-05-25 368) e4c9f422a8f55a Paul E. McKenney 2020-05-25 369 for (r = 0; r < nreaders; r++) { 786a2549774369 Joel Fernandes (Google 2020-05-25 370) atomic_set(&reader_tasks[r].start, 1); 786a2549774369 Joel Fernandes (Google 2020-05-25 371) wake_up(&reader_tasks[r].wq); 786a2549774369 Joel Fernandes (Google 2020-05-25 372) } 786a2549774369 Joel Fernandes (Google 2020-05-25 373) 786a2549774369 Joel Fernandes (Google 2020-05-25 374) VERBOSE_PERFOUT("main_func: experiment started, waiting for %d readers", e4c9f422a8f55a Paul E. McKenney 2020-05-25 375 nreaders); 786a2549774369 Joel Fernandes (Google 2020-05-25 376) 786a2549774369 Joel Fernandes (Google 2020-05-25 377) wait_event(main_wq, 786a2549774369 Joel Fernandes (Google 2020-05-25 378) !atomic_read(&nreaders_exp) || torture_must_stop()); 786a2549774369 Joel Fernandes (Google 2020-05-25 379) 786a2549774369 Joel Fernandes (Google 2020-05-25 380) VERBOSE_PERFOUT("main_func: experiment ended"); 786a2549774369 Joel Fernandes (Google 2020-05-25 381) 786a2549774369 Joel Fernandes (Google 2020-05-25 382) if (torture_must_stop()) 786a2549774369 Joel Fernandes (Google 2020-05-25 383) goto end; 786a2549774369 Joel Fernandes (Google 2020-05-25 384) e4c9f422a8f55a Paul E. McKenney 2020-05-25 385 result_avg[exp] = 1000 * process_durations(nreaders) / (nreaders * loops); 786a2549774369 Joel Fernandes (Google 2020-05-25 386) } 786a2549774369 Joel Fernandes (Google 2020-05-25 387) 786a2549774369 Joel Fernandes (Google 2020-05-25 388) // Print the average of all experiments 786a2549774369 Joel Fernandes (Google 2020-05-25 389) PERFOUT("END OF TEST. Calculating average duration per loop (nanoseconds)...\n"); 786a2549774369 Joel Fernandes (Google 2020-05-25 390) 786a2549774369 Joel Fernandes (Google 2020-05-25 @391) buf[0] = 0; 786a2549774369 Joel Fernandes (Google 2020-05-25 392) strcat(buf, "\n"); 786a2549774369 Joel Fernandes (Google 2020-05-25 393) strcat(buf, "Threads\tTime(ns)\n"); 786a2549774369 Joel Fernandes (Google 2020-05-25 394) e4c9f422a8f55a Paul E. McKenney 2020-05-25 395 for (exp = 0; exp < nruns; exp++) { 7e2a6278a303f5 Paul E. McKenney 2020-05-25 396 if (errexit) e4c9f422a8f55a Paul E. McKenney 2020-05-25 397 break; e4c9f422a8f55a Paul E. McKenney 2020-05-25 398 sprintf(buf1, "%d\t%llu.%03d\n", exp + 1, result_avg[exp] / 1000, (int)(result_avg[exp] % 1000)); 786a2549774369 Joel Fernandes (Google 2020-05-25 399) strcat(buf, buf1); 786a2549774369 Joel Fernandes (Google 2020-05-25 400) } 786a2549774369 Joel Fernandes (Google 2020-05-25 401) 7e2a6278a303f5 Paul E. McKenney 2020-05-25 402 if (!errexit) 786a2549774369 Joel Fernandes (Google 2020-05-25 403) PERFOUT("%s", buf); 786a2549774369 Joel Fernandes (Google 2020-05-25 404) 786a2549774369 Joel Fernandes (Google 2020-05-25 405) // This will shutdown everything including us. 786a2549774369 Joel Fernandes (Google 2020-05-25 406) if (shutdown) { 786a2549774369 Joel Fernandes (Google 2020-05-25 407) shutdown_start = 1; 786a2549774369 Joel Fernandes (Google 2020-05-25 408) wake_up(&shutdown_wq); 786a2549774369 Joel Fernandes (Google 2020-05-25 409) } 786a2549774369 Joel Fernandes (Google 2020-05-25 410) 786a2549774369 Joel Fernandes (Google 2020-05-25 411) // Wait for torture to stop us 786a2549774369 Joel Fernandes (Google 2020-05-25 412) while (!torture_must_stop()) 786a2549774369 Joel Fernandes (Google 2020-05-25 413) schedule_timeout_uninterruptible(1); 786a2549774369 Joel Fernandes (Google 2020-05-25 414) 786a2549774369 Joel Fernandes (Google 2020-05-25 415) end: 786a2549774369 Joel Fernandes (Google 2020-05-25 416) torture_kthread_stopping("main_func"); 7e2a6278a303f5 Paul E. McKenney 2020-05-25 417 kfree(result_avg); 7e2a6278a303f5 Paul E. McKenney 2020-05-25 418 kfree(buf); 786a2549774369 Joel Fernandes (Google 2020-05-25 419) return 0; 786a2549774369 Joel Fernandes (Google 2020-05-25 420) } 786a2549774369 Joel Fernandes (Google 2020-05-25 421) :::::: The code at line 391 was first introduced by commit :::::: 786a25497743696d79592b864cafbfe48787e6e1 refperf: Add a test to measure performance of read-side synchronization :::::: TO: Joel Fernandes (Google) <j...@joelfernandes.org> :::::: CC: Paul E. McKenney <paul...@kernel.org> --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-...@lists.01.org
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