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Message-ID: <YTDbFyJr80xtAaXf@krava>
Date:   Thu, 2 Sep 2021 16:09:27 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Steven Rostedt <srostedt@...are.com>
Cc:     kbuild@...ts.01.org, Jiri Olsa <jolsa@...nel.org>, lkp@...el.com,
        kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org
Subject: Re: [jolsa-perf:ftrace/direct 5/8] kernel/trace/ftrace.c:5150
 register_ftrace_direct() error: uninitialized symbol 'entry'.

On Wed, Sep 01, 2021 at 01:27:17PM +0300, Dan Carpenter wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git ftrace/direct
> head:   95a037919f1906d8bf164fb0c0066c9f298df139
> commit: b45bdf4de5473d5c15090eceeb72a2d5082cde2d [5/8] ftrace: Add ftrace_add_rec_direct function
> config: x86_64-randconfig-m001-20210831 (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@...el.com>
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>


Steven,
I have fix for this one.. I'll wait if there are any review comments
and then post all together

thanks,
jirka

> 
> smatch warnings:
> kernel/trace/ftrace.c:5150 register_ftrace_direct() error: uninitialized symbol 'entry'.
> 
> vim +/entry +5150 kernel/trace/ftrace.c
> 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5111) int register_ftrace_direct(unsigned long ip, unsigned long addr)
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5112) {
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5113) 	struct ftrace_direct_func *direct;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5114) 	struct ftrace_func_entry *entry;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5115) 	struct ftrace_hash *free_hash = NULL;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5116) 	struct dyn_ftrace *rec;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5117) 	int ret = -EBUSY;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5118) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5119) 	mutex_lock(&direct_mutex);
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5120) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5121) 	/* See if there's a direct function at @ip already */
> ff205766dbbee0 Alexei Starovoitov      2019-12-08  5122  	if (ftrace_find_rec_direct(ip))
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5123) 		goto out_unlock;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5124) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5125) 	ret = -ENODEV;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5126) 	rec = lookup_rec(ip, ip);
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5127) 	if (!rec)
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5128) 		goto out_unlock;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5129) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5130) 	/*
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5131) 	 * Check if the rec says it has a direct call but we didn't
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5132) 	 * find one earlier?
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5133) 	 */
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5134) 	if (WARN_ON(rec->flags & FTRACE_FL_DIRECT))
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5135) 		goto out_unlock;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5136) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5137) 	/* Make sure the ip points to the exact record */
> 406acdd32d3e7d Steven Rostedt (VMware  2019-11-15  5138) 	if (ip != rec->ip) {
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5139) 		ip = rec->ip;
> 406acdd32d3e7d Steven Rostedt (VMware  2019-11-15  5140) 		/* Need to check this ip for a direct. */
> ff205766dbbee0 Alexei Starovoitov      2019-12-08  5141  		if (ftrace_find_rec_direct(ip))
> 406acdd32d3e7d Steven Rostedt (VMware  2019-11-15  5142) 			goto out_unlock;
> 406acdd32d3e7d Steven Rostedt (VMware  2019-11-15  5143) 	}
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5144) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5145) 	ret = -ENOMEM;
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5146) 	direct = ftrace_find_direct_func(addr);
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5147) 	if (!direct) {
> 8a141dd7f7060d Alexei Starovoitov      2021-03-16  5148  		direct = ftrace_alloc_direct_func(addr);
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5149) 		if (!direct) {
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08 @5150) 			kfree(entry);
> 
> Delete this kfree.  "entry" isn't initialized yet.
> 
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5151) 			goto out_unlock;
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5152) 		}
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5153) 	}
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5154) 
> b45bdf4de5473d Jiri Olsa               2021-05-18  5155  	entry = ftrace_add_rec_direct(ip, addr, &free_hash);
>                                                                 ^^^^^^
> 
> b45bdf4de5473d Jiri Olsa               2021-05-18  5156  	if (!entry)
> b45bdf4de5473d Jiri Olsa               2021-05-18  5157  		goto out_unlock;
> 
> This patch should probably do free direct or something.  The error
> handling in this function is quite confusing so I'm not exactly sure.
> 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5158) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5159) 	ret = ftrace_set_filter_ip(&direct_ops, ip, 0, 0);
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5160) 	if (ret)
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5161) 		remove_hash_entry(direct_functions, entry);
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5162) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5163) 	if (!ret && !(direct_ops.flags & FTRACE_OPS_FL_ENABLED)) {
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5164) 		ret = register_ftrace_function(&direct_ops);
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5165) 		if (ret)
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5166) 			ftrace_set_filter_ip(&direct_ops, ip, 1, 0);
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5167) 	}
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5168) 
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5169) 	if (ret) {
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5170) 		kfree(entry);
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5171) 		if (!direct->count) {
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5172) 			list_del_rcu(&direct->next);
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5173) 			synchronize_rcu_tasks();
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5174) 			kfree(direct);
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5175) 			if (free_hash)
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5176) 				free_ftrace_hash(free_hash);
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5177) 			free_hash = NULL;
> a3ad1a7e396890 Steven Rostedt (VMware  2019-11-08  5178) 			ftrace_direct_func_count--;
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5179) 		}
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5180) 	} else {
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5181) 		direct->count++;
> 013bf0da047481 Steven Rostedt (VMware  2019-11-08  5182) 	}
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5183)  out_unlock:
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5184) 	mutex_unlock(&direct_mutex);
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5185) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5186) 	if (free_hash) {
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5187) 		synchronize_rcu_tasks();
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5188) 		free_ftrace_hash(free_hash);
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5189) 	}
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5190) 
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5191) 	return ret;
> 763e34e74bb7d5 Steven Rostedt (VMware  2019-11-08  5192) }
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
> 

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