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Date:   Sat, 17 Nov 2018 05:55:00 +0800
From:   kbuild test robot <lkp@intel.com>
To:     Matt Mullins <mmullins@fb.com>
Cc:     kbuild-all@01.org, ast@kernel.org, daniel@iogearbox.net,
        netdev@vger.kernel.org, kernel-team@fb.com,
        Matt Mullins <mmullins@fb.com>, Jessica Yu <jeyu@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next] bpf: support raw tracepoints in modules
Message-ID: <201811170557.4EtvwhsA%fengguang.wu@intel.com>
References: <20181109220632.3944136-1-mmullins@fb.com>
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Hi Matt,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/0day-ci/linux/commits/Matt-Mullins/bpf-support-raw-tracepoints-in-modules/20181110-144839
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master

smatch warnings:
kernel/trace/bpf_trace.c:1284 bpf_event_notify() error: potential null dereference 'btm'.  (kzalloc returns null)

vim +/btm +1284 kernel/trace/bpf_trace.c

  1269	
  1270	#ifdef CONFIG_MODULES
  1271	int bpf_event_notify(struct notifier_block *nb, unsigned long op, void *module)
  1272	{
  1273		struct bpf_trace_module *btm, *tmp;
  1274		struct module *mod = module;
  1275	
  1276		if (mod->num_bpf_raw_events == 0)
  1277			return 0;
  1278	
  1279		mutex_lock(&bpf_module_mutex);
  1280	
  1281		switch (op) {
  1282		case MODULE_STATE_COMING:
  1283			btm = kzalloc(sizeof(*btm), GFP_KERNEL);
> 1284			btm->module = module;
  1285			list_add(&btm->list, &bpf_trace_modules);
  1286			break;
  1287		case MODULE_STATE_GOING:
  1288			list_for_each_entry_safe(btm, tmp, &bpf_trace_modules, list) {
  1289				if (btm->module == module) {
  1290					list_del(&btm->list);
  1291					kfree(btm);
  1292					break;
  1293				}
  1294			}
  1295			break;
  1296		}
  1297	
  1298		mutex_unlock(&bpf_module_mutex);
  1299	
  1300		return 0;
  1301	}
  1302	

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