linux-kernel - [congwang:sch_bpf-kptr 3/5] net/sched/sch_bpf.c:186:3: warning: variable 'cl' is uninitialized when used here

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Message-ID: <202210062319.93rlEYNS-lkp@intel.com>
Date:   Thu, 6 Oct 2022 23:27:30 +0800
From:   kernel test robot <lkp@...el.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: [congwang:sch_bpf-kptr 3/5] net/sched/sch_bpf.c:186:3: warning:
 variable 'cl' is uninitialized when used here

tree:   https://github.com/congwang/linux.git sch_bpf-kptr
head:   efc61283d209bbec088ffc83043b9320534faa62
commit: e15fc84b6c56582f8dce2101e7ba9b634681e956 [3/5] net_sched: introduce eBPF based Qdisc
config: i386-allyesconfig
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
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
        # https://github.com/congwang/linux/commit/e15fc84b6c56582f8dce2101e7ba9b634681e956
        git remote add congwang https://github.com/congwang/linux.git
        git fetch --no-tags congwang sch_bpf-kptr
        git checkout e15fc84b6c56582f8dce2101e7ba9b634681e956
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/media/cec/usb/ net/sched/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

>> net/sched/sch_bpf.c:186:3: warning: variable 'cl' is uninitialized when used here [-Wuninitialized]
                   cl->overlimits++;
                   ^~
   net/sched/sch_bpf.c:171:26: note: initialize the variable 'cl' to silence this warning
           struct sch_bpf_class *cl;
                                   ^
                                    = NULL
   1 warning generated.


vim +/cl +186 net/sched/sch_bpf.c

   164	
   165	static struct sk_buff *sch_bpf_dequeue(struct Qdisc *sch)
   166	{
   167		struct sch_bpf_qdisc *q = qdisc_priv(sch);
   168		struct sk_buff *ret = NULL;
   169		struct sch_bpf_ctx ctx = {};
   170		struct bpf_prog *dequeue;
   171		struct sch_bpf_class *cl;
   172		s64 now;
   173		int res;
   174	
   175		dequeue = rcu_dereference(q->dequeue_prog.prog);
   176		ctx.classid = sch->handle;
   177		res = bpf_prog_run(dequeue, &ctx);
   178		switch (res) {
   179		case SCH_BPF_DEQUEUED:
   180			ret = (struct sk_buff *)ctx.skb;
   181			break;
   182		case SCH_BPF_THROTTLE:
   183			now = ktime_get_ns();
   184			qdisc_watchdog_schedule_ns(&q->watchdog, now + ctx.delay);
   185			qdisc_qstats_overlimit(sch);
 > 186			cl->overlimits++;
   187			return NULL;
   188		case SCH_BPF_PASS:
   189			cl = sch_bpf_find(sch, ctx.classid);
   190			if (!cl || !cl->qdisc)
   191				return NULL;
   192			ret = qdisc_dequeue_peeked(cl->qdisc);
   193			if (ret) {
   194				qdisc_bstats_update(sch, ret);
   195				qdisc_qstats_backlog_dec(sch, ret);
   196				sch->q.qlen--;
   197			}
   198		}
   199	
   200		return ret;
   201	}
   202	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

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