drivers/hwtracing/coresight/coresight-etm-perf.c:438:6: warning: variable 'event_data' is used uninitialized whenever 'if' condition is true

From: kernel test robot
Date: Mon Sep 27 2021 - 22:14:29 EST

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tree: https://github.com/0day-ci/linux/commits/James-Clark/coresight-Don-t-immediately-close-events-that-are-run-on-invalid-CPU-sink-combos/20210922-124616
head: 2e3df445ee8fbee18a1670a46b6f0296add37c17
commit: 2e3df445ee8fbee18a1670a46b6f0296add37c17 coresight: Don't immediately close events that are run on invalid CPU/sink combos
date: 6 days ago
config: arm64-randconfig-r013-20210927 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project dc6e8dfdfe7efecfda318d43a06fae18b40eb498)
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 arm64 cross compiling tool for clang build
# apt-get install binutils-aarch64-linux-gnu
# https://github.com/0day-ci/linux/commit/2e3df445ee8fbee18a1670a46b6f0296add37c17
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review James-Clark/coresight-Don-t-immediately-close-events-that-are-run-on-invalid-CPU-sink-combos/20210922-124616
git checkout 2e3df445ee8fbee18a1670a46b6f0296add37c17
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=arm64

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

All warnings (new ones prefixed by >>):

>> drivers/hwtracing/coresight/coresight-etm-perf.c:438:6: warning: variable 'event_data' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
if (WARN_ON(ctxt->event_data))
^~~~~~~~~~~~~~~~~~~~~~~~~
include/asm-generic/bug.h:120:28: note: expanded from macro 'WARN_ON'
#define WARN_ON(condition) ({ \
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/hwtracing/coresight/coresight-etm-perf.c:482:21: note: uninitialized use occurs here
ctxt->event_data = event_data;
^~~~~~~~~~
drivers/hwtracing/coresight/coresight-etm-perf.c:438:2: note: remove the 'if' if its condition is always false
if (WARN_ON(ctxt->event_data))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/hwtracing/coresight/coresight-etm-perf.c:434:6: warning: variable 'event_data' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
if (!csdev)
^~~~~~
drivers/hwtracing/coresight/coresight-etm-perf.c:482:21: note: uninitialized use occurs here
ctxt->event_data = event_data;
^~~~~~~~~~
drivers/hwtracing/coresight/coresight-etm-perf.c:434:2: note: remove the 'if' if its condition is always false
if (!csdev)
^~~~~~~~~~~
drivers/hwtracing/coresight/coresight-etm-perf.c:428:35: note: initialize the variable 'event_data' to silence this warning
struct etm_event_data *event_data;
^
= NULL
2 warnings generated.

vim +438 drivers/hwtracing/coresight/coresight-etm-perf.c

0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 424
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 425 static void etm_event_start(struct perf_event *event, int flags)
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 426 {
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 427 int cpu = smp_processor_id();
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 428 struct etm_event_data *event_data;
549452b73e6bf75 Suzuki K Poulose 2021-04-05 429 struct etm_ctxt *ctxt = this_cpu_ptr(&etm_ctxt);
549452b73e6bf75 Suzuki K Poulose 2021-04-05 430 struct perf_output_handle *handle = &ctxt->handle;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 431 struct coresight_device *sink, *csdev = per_cpu(csdev_src, cpu);
5ecabe4a76e8cdb Suzuki K Poulose 2018-09-20 432 struct list_head *path;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 433
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 434 if (!csdev)
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 435 goto fail;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 436
549452b73e6bf75 Suzuki K Poulose 2021-04-05 437 /* Have we messed up our tracking ? */
549452b73e6bf75 Suzuki K Poulose 2021-04-05 @438 if (WARN_ON(ctxt->event_data))
549452b73e6bf75 Suzuki K Poulose 2021-04-05 439 goto fail;
549452b73e6bf75 Suzuki K Poulose 2021-04-05 440
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 441 /*
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 442 * Deal with the ring buffer API and get a handle on the
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 443 * session's information.
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 444 */
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 445 event_data = perf_aux_output_begin(handle, event);
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 446 if (!event_data)
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 447 goto fail;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 448
859d510e58dac94 Suzuki K Poulose 2020-09-16 449 /*
859d510e58dac94 Suzuki K Poulose 2020-09-16 450 * Check if this ETM is allowed to trace, as decided
859d510e58dac94 Suzuki K Poulose 2020-09-16 451 * at etm_setup_aux(). This could be due to an unreachable
859d510e58dac94 Suzuki K Poulose 2020-09-16 452 * sink from this ETM. We can't do much in this case if
859d510e58dac94 Suzuki K Poulose 2020-09-16 453 * the sink was specified or hinted to the driver. For
859d510e58dac94 Suzuki K Poulose 2020-09-16 454 * now, simply don't record anything on this ETM.
2e3df445ee8fbee James Clark 2021-09-21 455 *
2e3df445ee8fbee James Clark 2021-09-21 456 * As such we pretend that everything is fine, and let
2e3df445ee8fbee James Clark 2021-09-21 457 * it continue without actually tracing. The event could
2e3df445ee8fbee James Clark 2021-09-21 458 * continue tracing when it moves to a CPU where it is
2e3df445ee8fbee James Clark 2021-09-21 459 * reachable to a sink.
859d510e58dac94 Suzuki K Poulose 2020-09-16 460 */
859d510e58dac94 Suzuki K Poulose 2020-09-16 461 if (!cpumask_test_cpu(cpu, &event_data->mask))
2e3df445ee8fbee James Clark 2021-09-21 462 goto out;
859d510e58dac94 Suzuki K Poulose 2020-09-16 463
5ecabe4a76e8cdb Suzuki K Poulose 2018-09-20 464 path = etm_event_cpu_path(event_data, cpu);
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 465 /* We need a sink, no need to continue without one */
5ecabe4a76e8cdb Suzuki K Poulose 2018-09-20 466 sink = coresight_get_sink(path);
3d6e89357583921 Suzuki K Poulose 2018-09-20 467 if (WARN_ON_ONCE(!sink))
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 468 goto fail_end_stop;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 469
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 470 /* Nothing will happen without a path */
3d6e89357583921 Suzuki K Poulose 2018-09-20 471 if (coresight_enable_path(path, CS_MODE_PERF, handle))
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 472 goto fail_end_stop;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 473
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 474 /* Finally enable the tracer */
68905d73df5d51b Mathieu Poirier 2016-08-25 475 if (source_ops(csdev)->enable(csdev, event, CS_MODE_PERF))
4f8ef21007531c3 Suzuki K Poulose 2018-09-20 476 goto fail_disable_path;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 477
2e3df445ee8fbee James Clark 2021-09-21 478 out:
2e3df445ee8fbee James Clark 2021-09-21 479 /* Tell the perf core the event is alive */
2e3df445ee8fbee James Clark 2021-09-21 480 event->hw.state = 0;
549452b73e6bf75 Suzuki K Poulose 2021-04-05 481 /* Save the event_data for this ETM */
549452b73e6bf75 Suzuki K Poulose 2021-04-05 482 ctxt->event_data = event_data;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 483 return;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 484
4f8ef21007531c3 Suzuki K Poulose 2018-09-20 485 fail_disable_path:
4f8ef21007531c3 Suzuki K Poulose 2018-09-20 486 coresight_disable_path(path);
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 487 fail_end_stop:
f4c0b0aa58d9b7e Will Deacon 2017-02-20 488 perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
f4c0b0aa58d9b7e Will Deacon 2017-02-20 489 perf_aux_output_end(handle, 0);
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 490 fail:
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 491 event->hw.state = PERF_HES_STOPPED;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 492 goto out;
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 493 }
0bcbf2e30ff2271 Mathieu Poirier 2016-02-17 494

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

Attachment: .config.gz
Description: application/gzip

Next message: Xiongwei Song: "Re: [PATCH RESEND 2/2] x86/mm: Randomize va with generic arch_pick_mmap_layout()"
Previous message: Yang Yingliang: "[PATCH -next v2] memory: tegra186-emc: Fix error return code in tegra186_emc_probe()"
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