Messages in this thread Patch in this message | | | From | Yafang Shao <> | Date | Mon, 13 Sep 2021 19:04:14 +0800 | Subject | Re: [peterz-queue:sched/core 13/19] kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444) |
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On Mon, Sep 13, 2021 at 4:48 PM Dan Carpenter <dan.carpenter@oracle.com> wrote: > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core > head: 2dfdb3d20ad50e2ae2cb84cbceb0f0fc75e79e5d > commit: 445d9e8ba05d5e9e4b26956b7fe529223e29d8d1 [13/19] sched: make struct sched_statistics independent of fair sched class > config: x86_64-randconfig-m001-20210910 (attached as .config) > compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kernel test robot <lkp@intel.com> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com> > > smatch warnings: > kernel/sched/debug.c:453 print_cfs_group_stats() warn: variable dereferenced before check 'se' (see line 444) >
Sorry, my bad.
Hi Peter,
Could you pls. help amend below change to the original commit ?
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 52b4426414c0..d59f33ac06fe 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -440,11 +440,8 @@ void dirty_sched_domain_sysctl(int cpu) #ifdef CONFIG_FAIR_GROUP_SCHED static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg) { - struct sched_statistics __maybe_unused *stats; struct sched_entity *se = tg->se[cpu];
- stats = __schedstats_from_se(se); - #define P(F) SEQ_printf(m, " .%-30s: %lld\n", #F, (long long)F) #define P_SCHEDSTAT(F) SEQ_printf(m, " .%-30s: %lld\n", \ #F, (long long)schedstat_val(stats->F)) @@ -460,6 +457,8 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group PN(se->sum_exec_runtime);
if (schedstat_enabled()) { + struct sched_statistics *stats = __schedstats_from_se(se); + PN_SCHEDSTAT(wait_start); PN_SCHEDSTAT(sleep_start); PN_SCHEDSTAT(block_start);
> vim +/se +453 kernel/sched/debug.c > > 3866e845ed5222 kernel/sched/debug.c Steven Rostedt (Red Hat 2016-02-22 439) > ff9b48c3598732 kernel/sched_debug.c Bharata B Rao 2008-11-10 440 #ifdef CONFIG_FAIR_GROUP_SCHED > 5091faa449ee0b kernel/sched_debug.c Mike Galbraith 2010-11-30 441 static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group *tg) > ff9b48c3598732 kernel/sched_debug.c Bharata B Rao 2008-11-10 442 { > ff9b48c3598732 kernel/sched_debug.c Bharata B Rao 2008-11-10 443 struct sched_entity *se = tg->se[cpu]; > 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao 2021-09-05 @444 struct sched_statistics *stats = __schedstats_from_se(se); > ^^ > New unchecked dereference. > > ff9b48c3598732 kernel/sched_debug.c Bharata B Rao 2008-11-10 445 > 97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar 2018-03-03 446 #define P(F) SEQ_printf(m, " .%-30s: %lld\n", #F, (long long)F) > 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao 2021-09-05 447 #define P_SCHEDSTAT(F) SEQ_printf(m, " .%-30s: %lld\n", \ > 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao 2021-09-05 448 #F, (long long)schedstat_val(stats->F)) > 97fb7a0a8944bd kernel/sched/debug.c Ingo Molnar 2018-03-03 449 #define PN(F) SEQ_printf(m, " .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F)) > 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao 2021-09-05 450 #define PN_SCHEDSTAT(F) SEQ_printf(m, " .%-30s: %lld.%06ld\n", \ > 445d9e8ba05d5e kernel/sched/debug.c Yafang Shao 2021-09-05 451 #F, SPLIT_NS((long long)schedstat_val(stats->F))) > ff9b48c3598732 kernel/sched_debug.c Bharata B Rao 2008-11-10 452 > cd126afe838d7e kernel/sched/debug.c Yuyang Du 2015-07-15 @453 if (!se) > ^^^ > The old code assumed "se" can be NULL. > > 18bf2805d9b30c kernel/sched/debug.c Ben Segall 2012-10-04 454 return; > 18bf2805d9b30c kernel/sched/debug.c Ben Segall 2012-10-04 455 > ff9b48c3598732 kernel/sched_debug.c Bharata B Rao 2008-11-10 456 PN(se->exec_start); > ff9b48c3598732 kernel/sched_debug.c Bharata B Rao 2008-11-10 457 PN(se->vruntime); > > --- > 0-DAY CI Kernel Test Service, Intel Corporation > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org >
-- Thanks Yafang
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