Re: [PATCH v2 02/10] tracing/boot: Add per-event histogram action options

[kernel test robot <lkp@intel.com>]

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Hi Masami,

I love your patch! Perhaps something to improve:

[auto build test WARNING on trace/for-next]
[also build test WARNING on linux/master linus/master v5.14-rc5 next-20210809]
[cannot apply to tip/perf/core]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Masami-Hiramatsu/tracing-boot-Add-histogram-syntax-support-in-boot-time-tracing/20210809-235246
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git for-next
config: i386-randconfig-r014-20210809 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/f9498294f1e13e2ee4a0a6bec385e74f6603d633
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Masami-Hiramatsu/tracing-boot-Add-histogram-syntax-support-in-boot-time-tracing/20210809-235246
        git checkout f9498294f1e13e2ee4a0a6bec385e74f6603d633
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   kernel/trace/trace_boot.c: In function 'trace_boot_compose_hist_cmd':
>> kernel/trace/trace_boot.c:357:34: warning: passing argument 3 of 'append_str_nospace' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
     357 |    append_str_nospace(&buf, end, p);
         |                                  ^
   kernel/trace/trace_boot.c:198:50: note: expected 'char *' but argument is of type 'const char *'
     198 | append_str_nospace(char **bufp, char *end, char *str)
         |                                            ~~~~~~^~~


vim +357 kernel/trace/trace_boot.c

   296	
   297	/*
   298	 * Histogram boottime tracing syntax.
   299	 *
   300	 * ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist {
   301	 *	keys = <KEY>[,...]
   302	 *	values = <VAL>[,...]
   303	 *	sort = <SORT-KEY>[,...]
   304	 *	size = <ENTRIES>
   305	 *	name = <HISTNAME>
   306	 *	var { <VAR> = <EXPR> ... }
   307	 *	pause|continue|clear
   308	 *	onmax|onchange { var = <VAR>; <ACTION> [= <PARAM>] }
   309	 *	onmatch { event = <EVENT>; <ACTION> [= <PARAM>] }
   310	 *	filter = <FILTER>
   311	 * }
   312	 *
   313	 * Where <ACTION> are;
   314	 *
   315	 *	trace = <EVENT>, <ARG1>[, ...]
   316	 *	save = <ARG1>[, ...]
   317	 *	snapshot
   318	 */
   319	static int __init
   320	trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size)
   321	{
   322		struct xbc_node *node, *knode;
   323		char *end = buf + size;
   324		const char *p;
   325		int ret = 0;
   326	
   327		append_printf(&buf, end, "hist");
   328	
   329		ret = trace_boot_hist_add_array(hnode, &buf, end, "keys");
   330		if (ret < 0) {
   331			if (ret == -ENOENT)
   332				pr_err("hist requires keys.\n");
   333			return -EINVAL;
   334		}
   335	
   336		ret = trace_boot_hist_add_array(hnode, &buf, end, "values");
   337		if (ret == -EINVAL)
   338			return ret;
   339		ret = trace_boot_hist_add_array(hnode, &buf, end, "sort");
   340		if (ret == -EINVAL)
   341			return ret;
   342	
   343		p = xbc_node_find_value(hnode, "size", NULL);
   344		if (p)
   345			append_printf(&buf, end, ":size=%s", p);
   346	
   347		p = xbc_node_find_value(hnode, "name", NULL);
   348		if (p)
   349			append_printf(&buf, end, ":name=%s", p);
   350	
   351		node = xbc_node_find_child(hnode, "var");
   352		if (node) {
   353			xbc_node_for_each_key_value(node, knode, p) {
   354				/* Expression must not include spaces. */
   355				append_printf(&buf, end, ":%s=",
   356					      xbc_node_get_data(knode));
 > 357				append_str_nospace(&buf, end, p);
   358			}
   359		}
   360	
   361		/* Histogram control attributes (mutual exclusive) */
   362		if (xbc_node_find_child(hnode, "pause"))
   363			append_printf(&buf, end, ":pause");
   364		else if (xbc_node_find_child(hnode, "continue"))
   365			append_printf(&buf, end, ":continue");
   366		else if (xbc_node_find_child(hnode, "clear"))
   367			append_printf(&buf, end, ":clear");
   368	
   369		/* Histogram handler and actions */
   370		node = xbc_node_find_child(hnode, "onmax");
   371		if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)
   372			return -EINVAL;
   373		node = xbc_node_find_child(hnode, "onchange");
   374		if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)
   375			return -EINVAL;
   376		node = xbc_node_find_child(hnode, "onmatch");
   377		if (node && trace_boot_hist_add_handler(node, &buf, end, "event") < 0)
   378			return -EINVAL;
   379	
   380		p = xbc_node_find_value(hnode, "filter", NULL);
   381		if (p)
   382			append_printf(&buf, end, " if %s", p);
   383	
   384		if (buf == end) {
   385			pr_err("hist exceeds the max command length.\n");
   386			return -E2BIG;
   387		}
   388	
   389		return 0;
   390	}
   391	#else
   392	static int __init
   393	trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size)
   394	{
   395		return -EOPNOTSUPP;
   396	}
   397	#endif
   398	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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