linux-kernel - Re: [kbuild] [trace:ftrace/core 35/39] kernel/trace/trace_boot.c:420 trace_boot_init_histograms() warn: curly braces intended?

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Message-Id: <20210901110713.fed0ebd23c05033045953642@kernel.org>
Date:   Wed, 1 Sep 2021 11:07:13 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     kbuild@...ts.01.org, lkp@...el.com, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Subject: Re: [kbuild] [trace:ftrace/core 35/39]
 kernel/trace/trace_boot.c:420 trace_boot_init_histograms() warn: curly
 braces intended?

Hi Dan,

On Tue, 31 Aug 2021 21:45:11 +0300
Dan Carpenter <dan.carpenter@...cle.com> wrote:

> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git  ftrace/core
> head:   3dc65994e3c1c999be3d991cdc96705e167cb3b1
> commit: 5d4648a0415efc239ffb377bce1d389723eda25d [35/39] tracing/boot: Show correct histogram error command
> 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>
> 
> smatch warnings:
> kernel/trace/trace_boot.c:420 trace_boot_init_histograms() warn: curly braces intended?
> kernel/trace/trace_boot.c:421 trace_boot_init_histograms() error: uninitialized symbol 'tmp'.
> kernel/trace/trace_boot.c:421 trace_boot_init_histograms() warn: passing freed memory 'tmp'
> kernel/trace/trace_boot.c:422 trace_boot_init_histograms() error: double free of 'tmp'
> 
> vim +420 kernel/trace/trace_boot.c
> 
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  396  static void __init
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  397  trace_boot_init_histograms(struct trace_event_file *file,
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  398  			   struct xbc_node *hnode, char *buf, size_t size)
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  399  {
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  400  	struct xbc_node *node;
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  401  	const char *p;
> 5d4648a0415efc2 Masami Hiramatsu 2021-08-06  402  	char *tmp;
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  403  
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  404  	xbc_node_for_each_subkey(hnode, node) {
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  405  		p = xbc_node_get_data(node);
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  406  		if (!isdigit(p[0]))
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  407  			continue;
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  408  		/* All digit started node should be instances. */
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  409  		if (trace_boot_compose_hist_cmd(node, buf, size) == 0) {
> 5d4648a0415efc2 Masami Hiramatsu 2021-08-06  410  			tmp = kstrdup(buf, GFP_KERNEL);
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  411  			if (trigger_process_regex(file, buf) < 0)
> 5d4648a0415efc2 Masami Hiramatsu 2021-08-06  412  				pr_err("Failed to apply hist trigger: %s\n", tmp);
> 5d4648a0415efc2 Masami Hiramatsu 2021-08-06  413  			kfree(tmp);
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  414  		}
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  415  	}
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  416  
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  417  	if (xbc_node_find_child(hnode, "keys")) {
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  418  		if (trace_boot_compose_hist_cmd(hnode, buf, size) == 0)
> 
> The missing curly braces here trigger a ball of static checker warnings.
> I'm so happy about that.  :)

The ftrace/core branch has a wrong version of the patch. ftrae/for-next has
correct one. I think Steve correct this mismatch after he comes back.

Thank you,



> 
> 5d4648a0415efc2 Masami Hiramatsu 2021-08-06  419  			tmp = kstrdup(buf, GFP_KERNEL);
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06 @420  			if (trigger_process_regex(file, buf) < 0)
> 5d4648a0415efc2 Masami Hiramatsu 2021-08-06 @421  				pr_err("Failed to apply hist trigger: %s\n", tmp);
> 5d4648a0415efc2 Masami Hiramatsu 2021-08-06 @422  			kfree(tmp);
> 30cb856e3067e5d Masami Hiramatsu 2021-08-06  423  	}
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org 
> 
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-- 
Masami Hiramatsu <mhiramat@...nel.org>