[PATCH v20 06/20] perf, tools: Support alias descriptions

[Sukadev Bhattiprolu]

From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

Add support to print alias descriptions in perf list, which
are taken from the generated event files.

The sorting code is changed to put the events with descriptions
at the end. The descriptions are printed as possibly multiple word
wrapped lines.

Example output:

% perf list
...
  arith.fpu_div
       [Divide operations executed]
  arith.fpu_div_active
       [Cycles when divider is busy executing divide operations]

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---

Changelog
	- Delete a redundant free()

Changelog[v14]
	- [Jiri Olsa] Fail, rather than continue if strdup() returns NULL;
	  remove unnecessary __maybe_unused.
---
 tools/perf/util/pmu.c | 83 +++++++++++++++++++++++++++++++++++++++++----------
 tools/perf/util/pmu.h |  1 +
 2 files changed, 68 insertions(+), 16 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index eae0de1..496c02e 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -222,7 +222,7 @@ static int perf_pmu__parse_snapshot(struct perf_pmu_alias *alias,
 }
 
 static int __perf_pmu__new_alias(struct list_head *list, char *dir, char *name,
-				 char *desc __maybe_unused, char *val)
+				 char *desc, char *val)
 {
 	struct perf_pmu_alias *alias;
 	int ret;
@@ -255,6 +255,8 @@ static int __perf_pmu__new_alias(struct list_head *list, char *dir, char *name,
 		perf_pmu__parse_snapshot(alias, dir, name);
 	}
 
+	alias->desc = desc ? strdup(desc) : NULL;
+
 	list_add_tail(&alias->list, list);
 
 	return 0;
@@ -1035,11 +1037,42 @@ static char *format_alias_or(char *buf, int len, struct perf_pmu *pmu,
 	return buf;
 }
 
-static int cmp_string(const void *a, const void *b)
+struct pair {
+	char *name;
+	char *desc;
+};
+
+static int cmp_pair(const void *a, const void *b)
+{
+	const struct pair *as = a;
+	const struct pair *bs = b;
+
+	/* Put extra events last */
+	if (!!as->desc != !!bs->desc)
+		return !!as->desc - !!bs->desc;
+	return strcmp(as->name, bs->name);
+}
+
+static void wordwrap(char *s, int start, int max, int corr)
 {
-	const char * const *as = a;
-	const char * const *bs = b;
-	return strcmp(*as, *bs);
+	int column = start;
+	int n;
+
+	while (*s) {
+		int wlen = strcspn(s, " \t");
+
+		if (column + wlen >= max && column > start) {
+			printf("\n%*s", start, "");
+			column = start + corr;
+		}
+		n = printf("%s%.*s", column > start ? " " : "", wlen, s);
+		if (n <= 0)
+			break;
+		s += wlen;
+		column += n;
+		while (isspace(*s))
+			s++;
+	}
 }
 
 void print_pmu_events(const char *event_glob, bool name_only)
@@ -1049,7 +1082,9 @@ void print_pmu_events(const char *event_glob, bool name_only)
 	char buf[1024];
 	int printed = 0;
 	int len, j;
-	char **aliases;
+	struct pair *aliases;
+	int numdesc = 0;
+	int columns = 78;
 
 	pmu = NULL;
 	len = 0;
@@ -1059,14 +1094,15 @@ void print_pmu_events(const char *event_glob, bool name_only)
 		if (pmu->selectable)
 			len++;
 	}
-	aliases = zalloc(sizeof(char *) * len);
+	aliases = zalloc(sizeof(struct pair) * len);
 	if (!aliases)
 		goto out_enomem;
 	pmu = NULL;
 	j = 0;
 	while ((pmu = perf_pmu__scan(pmu)) != NULL) {
 		list_for_each_entry(alias, &pmu->aliases, list) {
-			char *name = format_alias(buf, sizeof(buf), pmu, alias);
+			char *name = alias->desc ? alias->name :
+				format_alias(buf, sizeof(buf), pmu, alias);
 			bool is_cpu = !strcmp(pmu->name, "cpu");
 
 			if (event_glob != NULL &&
@@ -1075,12 +1111,19 @@ void print_pmu_events(const char *event_glob, bool name_only)
 						       event_glob))))
 				continue;
 
-			if (is_cpu && !name_only)
+			if (is_cpu && !name_only && !alias->desc)
 				name = format_alias_or(buf, sizeof(buf), pmu, alias);
 
-			aliases[j] = strdup(name);
-			if (aliases[j] == NULL)
+			aliases[j].name = name;
+			if (is_cpu && !name_only && !alias->desc)
+				aliases[j].name = format_alias_or(buf,
+								  sizeof(buf),
+								  pmu, alias);
+			aliases[j].name = strdup(aliases[j].name);
+			if (!aliases[j].name)
 				goto out_enomem;
+
+			aliases[j].desc = alias->desc;
 			j++;
 		}
 		if (pmu->selectable &&
@@ -1088,25 +1131,33 @@ void print_pmu_events(const char *event_glob, bool name_only)
 			char *s;
 			if (asprintf(&s, "%s//", pmu->name) < 0)
 				goto out_enomem;
-			aliases[j] = s;
+			aliases[j].name = s;
 			j++;
 		}
 	}
 	len = j;
-	qsort(aliases, len, sizeof(char *), cmp_string);
+	qsort(aliases, len, sizeof(struct pair), cmp_pair);
 	for (j = 0; j < len; j++) {
 		if (name_only) {
-			printf("%s ", aliases[j]);
+			printf("%s ", aliases[j].name);
 			continue;
 		}
-		printf("  %-50s [Kernel PMU event]\n", aliases[j]);
+		if (aliases[j].desc) {
+			if (numdesc++ == 0)
+				printf("\n");
+			printf("  %-50s\n", aliases[j].name);
+			printf("%*s", 8, "[");
+			wordwrap(aliases[j].desc, 8, columns, 0);
+			printf("]\n");
+		} else
+			printf("  %-50s [Kernel PMU event]\n", aliases[j].name);
 		printed++;
 	}
 	if (printed && pager_in_use())
 		printf("\n");
 out_free:
 	for (j = 0; j < len; j++)
-		zfree(&aliases[j]);
+		zfree(&aliases[j].name);
 	zfree(&aliases);
 	return;
 
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 5d7e844..11bda57 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -38,6 +38,7 @@ struct perf_pmu_info {
 
 struct perf_pmu_alias {
 	char *name;
+	char *desc;
 	struct list_head terms; /* HEAD struct parse_events_term -> list */
 	struct list_head list;  /* ELEM */
 	char unit[UNIT_MAX_LEN+1];
-- 
2.5.3