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Date:	Tue, 07 Oct 2014 12:17:05 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Hemant Kumar <hemant@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, srikar@...ux.vnet.ibm.com,
	peterz@...radead.org, oleg@...hat.com,
	hegdevasant@...ux.vnet.ibm.com, mingo@...hat.com, anton@...hat.com,
	systemtap@...rceware.org, masami.hiramatsu.pt@...achi.com,
	aravinda@...ux.vnet.ibm.com, penberg@....fi
Subject: Re: [PATCH v2 4/5] perf/sdt: Delete SDT events from cache

On Wed, 01 Oct 2014 08:18:41 +0530, Hemant Kumar wrote:
> This patch adds the support to delete SDT events from the cache.
> To delete an event corresponding to a file, first the cache is read into
> the file_hash list. The key is calculated from the file name.
> And then, the file_list for that file_hash entry is traversed to find out
> the target file_list entry. Once, it is found, its contents are all freed up.
>
> # ./perf sdt-cache --del /usr/lib64/libc-2.16.so
>
> 8 events removed for /usr/lib64/libc-2.16.so!
>
> Signed-off-by: Hemant Kumar <hemant@...ux.vnet.ibm.com>
> ---
>  tools/perf/builtin-sdt-cache.c |   28 +++++++++++++++++++++++++++-
>  tools/perf/util/parse-events.h |    1 +
>  tools/perf/util/sdt.c          |   35 +++++++++++++++++++++++++++++++++++
>  3 files changed, 63 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-sdt-cache.c b/tools/perf/builtin-sdt-cache.c
> index 5faf8e5..12276da 100644
> --- a/tools/perf/builtin-sdt-cache.c
> +++ b/tools/perf/builtin-sdt-cache.c
> @@ -16,6 +16,7 @@
>  /* Session management structure */
>  static struct {
>  	bool add;
> +	bool del;
>  	bool dump;
>  	const char *target;
>  } params;
> @@ -29,6 +30,15 @@ static int opt_add_sdt_events(const struct option *opt __maybe_unused,
>  	return 0;
>  }
>  
> +static int opt_del_sdt_events(const struct option *opt __maybe_unused,
> +			      const char *str, int unset __maybe_unused)
> +{
> +	params.del = true;
> +	params.target = str;
> +
> +	return 0;
> +}
> +
>  static int opt_show_sdt_events(const struct option *opt __maybe_unused,
>  			       const char *str, int unset __maybe_unused)
>  {
> @@ -45,13 +55,17 @@ int cmd_sdt_cache(int argc, const char **argv, const char *prefix __maybe_unused
>  		OPT_CALLBACK('a', "add", NULL, "filename",
>  			     "add SDT events from a file.",
>  			     opt_add_sdt_events),
> +		OPT_CALLBACK('d', "del", NULL, "filename",
> +			     "Remove SDT events corresponding to a file from the"
> +			     " sdt cache.",
> +			     opt_del_sdt_events),
>  		OPT_CALLBACK_NOOPT('s', "dump", NULL, "show SDT events",
>  				   "Read SDT events from cache and display.",
>  				   opt_show_sdt_events),
>  		OPT_END()
>  	};
>  	const char * const sdt_cache_usage[] = {
> -		"perf sdt_cache [--add filename | --dump]",
> +		"perf sdt_cache [--add filename | --del filename | --dump]",

I think it'd be better split the usage into two lines:

		"perf sdt_cache [--add | --del] <filename>"
		"perf sdt_cache --dump"


>  		NULL
>  	};
>  
> @@ -63,6 +77,10 @@ int cmd_sdt_cache(int argc, const char **argv, const char *prefix __maybe_unused
>  
>  	symbol__elf_init();
>  	if (params.add) {
> +		if (params.del) {
> +			pr_err("Error: Don't use --del with --add\n");
> +			usage_with_options(sdt_cache_usage, sdt_cache_options);
> +		}
>  		if (params.dump) {
>  			pr_err("Error: Don't use --dump with --add\n");
>  			usage_with_options(sdt_cache_usage, sdt_cache_options);
> @@ -70,6 +88,14 @@ int cmd_sdt_cache(int argc, const char **argv, const char *prefix __maybe_unused
>  		ret = add_sdt_events(params.target);
>  		if (ret < 0)
>  			pr_err("Cannot add SDT events to cache!\n");
> +	} else if (params.del) {
> +		if (params.dump) {
> +			pr_err("Error: Don't use --dump with --del\n");
> +			usage_with_options(sdt_cache_usage, sdt_cache_options);
> +		}
> +		ret = remove_sdt_events(params.target);
> +		if (ret < 0)
> +			pr_err("Cannot remove SDT events from cache!\n");
>  	} else if (params.dump) {
>  		if (argc == 0) {
>  			ret = dump_sdt_events();

I think we need to a flag for exclusive options so that it can emit
warnings like this automatically during option parsing.

Thanks,
Namhyung


> diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
> index f43e6aa..2297af7 100644
> --- a/tools/perf/util/parse-events.h
> +++ b/tools/perf/util/parse-events.h
> @@ -111,5 +111,6 @@ extern int valid_debugfs_mount(const char *debugfs);
>  
>  int add_sdt_events(const char *file);
>  int dump_sdt_events(void);
> +int remove_sdt_events(const char *str);
>  
>  #endif /* __PERF_PARSE_EVENTS_H */
> diff --git a/tools/perf/util/sdt.c b/tools/perf/util/sdt.c
> index f2c7dc0..e8eea48 100644
> --- a/tools/perf/util/sdt.c
> +++ b/tools/perf/util/sdt.c
> @@ -711,3 +711,38 @@ int dump_sdt_events(void)
>  	file_hash_list__display(&file_hash);
>  	return 0;
>  }
> +
> +/**
> + * remove_sdt_events: remove SDT events from cache
> + * @str: filename
> + *
> + * Removes the SDT events from the cache corresponding to the file name
> + * @str.
> + */
> +int remove_sdt_events(const char *str)
> +{
> +	struct hash_list file_hash;
> +	char *res_path;
> +	int nr_del;
> +
> +	/* Initialize the hash_lists */
> +	file_hash_list__init(&file_hash);
> +	res_path = realpath(str, NULL);
> +	if (!res_path)
> +		return -ENOMEM;
> +
> +	/* Remove the file_list entry from file_hash and update the event_hash */
> +	nr_del = file_hash_list__remove(&file_hash, res_path);
> +	if (nr_del > 0) {
> +		printf("%d events removed for %s!\n", nr_del, res_path);
> +		flush_hash_list_to_cache(&file_hash);
> +		goto out;
> +	} else if (!nr_del) {
> +		pr_err("Events for %s not found!\n", str);
> +	}
> +
> +out:
> +	free(res_path);
> +	file_hash_list__cleanup(&file_hash);
> +	return nr_del;
> +}
--
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